This writeup was lead-authored by our senior scientist, Sunbin Song, PhD. Sunbin graduated from MIT with a degree in Biology before receiving a doctorate in neuroscience from Georgetown and becoming a research scientist at the NIH. When Sunbin isn't busy researching the brain, she loves to explore how we can best nurture our body, mind and spirit to live more joyful lives.

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Thinning hair is a normal part of aging for men and women alike. There are many reasons for thinning including aging hair follicles, hormonal changes, poor blood flow, chronic inflammation, and aging in scalp skin which affect hair thickness, rate of growth, and hair density.  

To achieve a thicker, fuller head of hair, it is important to rejuvenate the scalp skin and hair follicles as well as to protect and condition the visible hair shafts which is the hair you can see.  

The only living, growing part of your hair is inside your scalp skin where the hair follicles reside. Hence, to grow thicker hair at a higher density, a scalp serum or other product targeting the scalp is recommended. That is why we created the Full Follicle haircare line which includes a scalp serum, a scalp stimulating shampoo, and an advanced treatment conditioner (learn more). 

The visible hair shafts you can see are actually not composed of living cells. However, these cells have a protective waterproof coating around them that can get easily damaged by combing, styling, blow-drying, coloring, and improperly cleansing which strips the hair’s natural waterproofing. It will look sleek and shiny or brittle and damaged based on the integrity of the waterproofing and the extent of damage to the interior parts of the hair. Modern shampoos and conditioners aim to prevent the stripping of waterproofing while also repairing the damage on the hair and re-coating it with waterproofing.

In this in-depth newsletter, you will learn all about hair, how it grows from the hair follicle, why it starts to thin and bald with age, and ways to reverse that trend. We will also go over the appropriate cleansers and conditioners to preserve and repair the natural coating on the hair shaft particularly in the case of thin or damaged hair.

Hair follicle structure

Most of the hair on our body surface is tiny and virtually colorless (vellus hair). However, the hair in places such as our scalp, eyelashes, and eyebrows is longer, thicker, and highly pigmented (terminal hair). Your genetics determine the color of your hair, as well as whether it is straight, helical or wavy, as well as its length, diameter, density and cross-sectional shape. No matter your starting point, as you age, factors start to come into play that leads to loss of pigmentation resulting in greying, a loss of hair thickness resulting in thinning hair, slower hair growth, decreased hair density, and in some cases balding (Buffoli et al. 2014). 

These aging related changes are all taking place inside your scalp skin within the dermal layer where the part of the hair known as the hair follicle resides. The visible part of hair growing outside of your scalp is called the hair shaft, and is actually made up of dead hair cells. Inside the skin is where all the living hair growth (and resultant hair thinning and hair loss) occurs. If you are dealing with thinning hair due to aging, the key to a thicker, denser head of hair lies in the scalp skin and hair follicles.

The hair bulb is the part of the hair follicle which is actively producing growth of the hair shaft. It contains the matrix and dermal papilla cells (DPCs), mucopolysaccharide-rich stroma, nerve fibers and a capillary loop that provides the blood supply. Here, melanocytes produce the melanin pigments which give hair its color. Growth factors are also produced to stimulate hair growth. The new hair cells are born in the lower part of the hair bulb and as they move upwards, they increase in volume and become vertically elongated. Finally they are hyalinized so that the keratin of the hair is stabilized (Ohn et al. 2019, Buffoli et al 2014).

Hair follicle growth stages

Now as mentioned, the lower part of the follicle shrinks and regenerates according to the phase of growth the follicle is in. At any given time, your hair follicle can be in one of three stages that represent either a growth phase (anagen), or a period of non-growth (catagen, telogen). Catagen is a period of regression and telogen a period of rest. Some may also describe a fourth stage which is the period in which the hair sheds and the follicle transitions back to anagen (may be called exogen or regeneration phase). 

(Growth stages reproduced from Jang et al. 2023)

Hair follicles have a bulge area where the arrector pili muscle inserts. The duct of the sebaceous gland also empties here. The sebaceous gland secretes oily sebum which is what makes your hair and scalp oily. The upper part of the bulge is the infundibulum and the isthmus region. The lower part of the bulge is the supra-bulbar area and the hair bulb region. The upper part of the follicle is permanent but the lower part regenerates cyclically based on the growth phase.

Throughout these regions of the hair follicle are two layers called the outer root sheath and the inner root sheath. The inner root sheath holds the hair shaft which is the visible part of hair. On the skin side of the outer root sheath there is also a connective tissue layer which consists of two layers of collagen fibers. This skin layer is called the glassy layer or dermal sheet.

(Hair Follicle Figure reproduced from Buffoli et al 2014). 

The inner root sheath has three sublayers (Henle’s layer, Huxley’s layer, and the cuticle layer). The inner root sheath anchors the hair shaft to the follicle and produces keratins and trichohyalins that act like cement between cells so it can hold and support the hair shaft. It’s rigid casing determines the shape of the hair as it grows, guiding its upward movement and determining whether it is curly or straight.

In the scalp, the anagen (growth) phase typically lasts for 2-8 years with a hair growth rate of approximately 1 cm per month. The anagen phase eventually ends and hair growth stops to enter into the catagen (regression) phase. Catagen lasts for several weeks and during this time, changes in the hair follicle occur to facilitate the transition to the telogen (rest) phase which lasts for 2-4 months. 

Hair Follicle Stem Cells (HFSCs) are responsible for regenerating the hair follicle for the anagen growth phase. Matrix cells give rise to the actual hair shaft that is the visible hair strand. Dermal papilla cells (DPCs) regulate the growth of matrix cells by sending signals that determine the growth stage of the hair. These stimulating signals include growth factors and/or extracellular matrix factors (Natarelli et al. 2023).

At any given moment approximately 10-15% of hairs are in this telogen resting phase. At the end of telogen, the hair falls out (exogen phase) and a few weeks later, the hair follicle re-enters the anagen phase. Most individuals have about 100,000 scalp hairs at any time, with a normal shedding rate of 100-150 telogen hairs per day (Buffoli et al. 2014, Natarelli et al. 2023).

Changes in hair with aging and other factors

Now that you understand how the hair follicle is structured and how growth and rest phases determine growth and density, you can understand better how aging can lead to hair thinning, greying, and loss. 

With aging, there is an increase of hair follicles in the telogen rest phase versus the anagen growth phase leading to loss of density. Anagen phase length also decreases with age. Hair growing out of the follicle is smaller in diameter (and hence thinner), and grows more slowly, as well as with increased surface roughness. Anagen hair also sheds prematurely with aging. Some terminal hair follicles disappear altogether leading to a decrease in the number of terminal hair follicles in general. Greying is caused by a loss of melanocytes in the hair bulb leading to a loss of hair color (Buffoli et al. 2014, Natarelli et al. 2023). These age-related changes are driven be several factors which we will detail in this section.

Sex hormones and Hair

Androgenic Alopecia (Male pattern baldness)

Hormonal changes, and in particular changes in sex hormones, lead to age-related changes in hair. In simplistic terms, ‘male hormones’ help males grow beards but can also lead to loss of hair in the scalp regions. Meanwhile, ‘female hormones’ promote hair growth on the scalp regions. Much of these hormones are synthesized by the skin and hair follicles themselves. Now let’s go a little bit deeper.

Let’s start first with the androgens which are colloquially known as “male hormones” although they are also found in women at much lower levels. The best known androgen is testosterone but the most potent androgen is dihydrotestosterone or DHT.

DHT is largely responsible for ‘male pattern baldness’ also known as ‘androgenic alopecia.’ DHT directly affects dermal papillae cells (DPCs) to signal a shortened growth anagen phase and a prolonged telogen phase. This in turn leads to the production of shorter, thinner hair shafts. DHT also enhances apoptosis of hair cells, and the hair follicle miniaturizes in a process called follicular miniaturization. The hair then converts from a terminal hair into a vellus hair (Deng et al. 2022, Ohn et al. 2019, Bansal et al. 2012). 

Androgenic alopecia is very common and affects nearly 50% of men by the age of 50 years (Bassino et al. 2020). DHT causes hair in some areas like the face to grow supporting a beard, but it causes hair on the scalp to bald. With male pattern baldness, there is a genetically determined increased production of DHT in the frontal scalp leading to baldness in a pattern. Specifically, the enzyme 5a-Reductase which converts testosterone into DHT is increased above normal levels leading to higher than normal DHT levels (Liang et al. 2023). 

Some hair is independent of androgens such as hair on the eyebrows and lashes. However, hair on the scalp, beard, chest, armpit area, and pubic region respond to androgens. Androgens act through a single nuclear receptor, the androgen receptor (AR). ARs are present in epidermal keratinocytes, sebocytes, sweat gland cells, dermal fibroblasts, and genital melanocytes, as well as cells related to hair follicles including follicular keratinocytes and dermal papilla cells where a large proportion of receptors are located (Price 1975, Deng et al. 2022).

This makes sense when you think about the changes in hair patterns that occur in boys during puberty, in which hair in the beard region, the trunk, limbs, nostrils and ear region become thicker terminal hairs. Conversion to DHT which occurs in the skin and hair follicles is necessary for this normal part of development of male sexual characteristics. DHT formation in skin is relatively low in most skin areas except areas of androgen-mediated growth, which vary at different ages. Some women also have too much DHT formation in hair follicles resulting in beards as well as hair on the chest and back, and this is called ‘hirsutism’ (Price 1975, Zouboulis and Degitz 2004). 

The majority of testosterone in men is secreted by the testes and since testosterone levels in men decrease with age, this may be confusing as this means DHT levels should also decrease with age. Yet hair thinning and balding increase with age. This is in part because the availability of testosterone is not necessarily the rate-limiting factor. The adrenal glands also secrete androgens, though typically weaker androgens such as dehydroepiandrosterone (DHEA), dehydroepiandorosterone sulfate (DHEA-S) and androstenedione. In fact, DHEA-S is actually the androgen with by far the highest serum concentration in both sexes. These androgens are actually so weak, they are sometimes called prohormones since they need conversion to testosterone and DHT to be potent (Zouboulis 2007). Nonetheless, sebaceous glands, epidermal keratinocytes, and sweat glands have enzymes that can convert DHEA-S, DHEA, and androstenedione into testosterone. Enzyme 5a-Reductase found in sebaceous glands, epidermal keratinocytes, sweat glands and hair follicles can then convert testosterone to DHT. 

Second, the impact of DHT on hair follicles can combine with other aging factors that affect the hair follicle. This includes factors we will cover such as senescence, inflammation, and oxidative stress. Hence, it is the combination of factors that leads to hair loss (Deng et al. 2022).

Women are also affected by androgens like DHT although to a lesser extent. However, androgenic alopecia is not rare in women. Statistically, about 80% of men and 50% of women experience androgenic alopecia during their lifetime with increasing prevalence with aging. Men and women show different patterns of androgenic alopecia. Men typically having bitemporal recession of the frontal hair line followed by diffuse thinning of the vertex which sometimes produces a bald spot. In contrast, women have diffuse apical hair loss and a much milder presentation (Villani et al. 2022). 

The adrenal glands and ovaries in women secrete androgens, though the circulating amount in women is much lower than in men. Similarly to men, weaker androgens can be converted into testosterone and DHT. However, it can also be converted into estrogen in peripheral organs including the skin and hair follicles (Price 1975, Zouboulis 2007). In both sexes, the sebaceous glands may also convert testosterone and androstenedione into estrogen instead via the aromatase enzyme. 

In other words, in addition to the levels of these various hormones in your blood, depending on the levels of enzymes and receptors in your skin as determined by your sex and your genetics, you can end up with different levels of potent androgens like DHT or estrogens at the hair follicle level (Zouboulis and Degitz 2004, Zouboulis 2007). These sex and genetic factors then combine with other aging factors such as senescence or increased oxidative stress to lead to progressive hair thinning and hair loss with aging (Deng et al. 2022). 

Estrogens, Pregnancy and Menopause

In contrast to androgens, estrogen leads to an increased lushness in hair growth. Estrogen receptors are found in hair follicles and notably the hairs on your scalp. This is why there is increased lushness in your mane during pregnancy. Estrogen increases the number of hairs in the anagen growth phase. Postpartum, this hair sheds as your estrogen levels drop. Further, women have higher expression of aromatase enzymes in the scalp hair follicles means more estrogens are produced there. This can protect women from balding and encourage hair lushness. 

In women, the main source of estrogens in the bloodstream are the ovaries. At puberty, the ovarian follicles begin secreting estrogens of which there are two principal types: estradiol and estrone. Estradiol is much more potent - in fact seven to ten times more potent than estrone (Cui et al. 2013). A third type, estriol is involved in pregnancy and is secreted by the placenta. 

After menopause, the levels of estradiol in your bloodstream, which is the primary form of estrogen during your reproductive years, drops to near zero. This drop leads to many of the symptoms of perimenopause and menopause, including thinning hair as hair follicles lose the major input of estrogen. Estrogen is also important for the integrity of the skin around the hair follicles and so post-menopausal loss of collagen, elastin, and GAGs, and vascularization of the dermis may also contribute indirectly to thinning hair. 

After menopause, additional estrogens are produced by peripheral organs including fat tissue, liver, heart, brain and of course, the skin. In men and women, fat tissue is a major source of circulating estrogens in the bloodstream, while estrogens produced by the skin generally stays nearby and has its action near where it was made (Cui 2013). As mentioned, your skin has the aromatase enzyme which is involved in the formation of estrogens and can take circulating androgens and convert them into estrogens. Hence, post-menopause, the level of estrogens in your body does not drop to zero and can still support hair growth.

Estrogen has two types of estrogen receptors ERA (alpha) and ERB (beta). ERB is the more widely expressed estrogen receptor and is present in skin, hair follicles and a wide array of tissue types. In contrast, ERA is present mainly in reproductive tissues in both men and women including the gonads and the female mammary glands. ERA is therefore the main receptor type implicated in estrogen positive breast cancer (Thornton et al. 2002). The risk of breast cancer is why estrogen supplementation post-menopause is often treated with caution. 

Ultimately, (1) the loss of estrogens with perimenopause and menopause combined with (2) the relative levels of circulating androgens and estrogens and the levels of enzymes in skin and hair follicles that convert circulating androgens and estrogens into their more potent forms, (3) and the levels of receptors in these regions as determined by genetics can have a large impact on hair thinning in women. In general, around menopause, women have a decline is hair thickness, sebum production, and a drop in hair luster from an increase in hair fiber curvature (Villani et al. 2022).

Senescence

As you age, all the cells in your body undergo a process called “senescence” which essentially means a gradual deterioration in a cell’s ability to function, divide, and grow. This may be due to telomere damage, accumulated DNA damage, and mitochondrial dysfunction, growth arrest, and secretion of proinflammatory factors (Deng et al. 2022).

Indeed, there is a general decline growth factors and hair follicle stem cell (HFSC) activity with aging that decreases the ability of the hair follicle to regenerate. Also, in vitro, aged HFSCs themselves show decreased activity even when isolated compared to young HFSCs (Jang et al. 2023). This can be explained in part by altered responsiveness to cell signals that should lead HFSCs to enter a growth stage (Deng et al. 2022). 

Further, in senescent cells, there is a decrease in mitochondrial efficiency which leads to greater production of free radicals with aging. Simultaneously there is a drop in activity of enzymes that scavenge free radicals increasing oxidative stress (Deng et al. 2022). Melanocyte stem cells (MeSCs) that make pigment that gives hair its color also decline which leads to graying. However, this decline is beyond decreasing activity. The number of MeSCs decrease rapidly with aging until they are entirely depleted and is likely related to oxidative stress (Jang et al. 2023).

Chronic Inflammation

With aging there is an increase in levels of inflammatory cytokines around the hair follicles. Age dependent chronically elevated levels of inflammatory cytokines in the epidermal layer of aged skin inhibits HFSC function. Animal studies show that reversing inflammation can lead to some hair regrowth in aged mice (Jang et al. 2023).

Chronic inflammation is closely correlated to hair thinning and hair loss. Inflammation can also impair melanocytes contributing to hair graying as well. Other factors such as obesity, psychological stress or diseases such as progeria can also drive chronic inflammation around the hair follicle to drive hair thinning, loss and graying (Liang et al. 2023). Chronic stress accelerates hair aging and hair loss through corticosterone. Corticosterone which is the major stress hormone in humans, prevents HFSCs from entering into anagen via a glucocorticoid receptor signally pathway leading to hair thinning and loss (Liang et al. 2023).

Bacteria, fungi and mites live in the scalp feeding off sebum and contribute to conditions like dandruff. As you age, you are worse at fending off microbes. Demodox mite infestation can increase with aging and lead to contribute to inflammation leading to hair thinning (Liang et al. 2023).

Oxidative Stress 

As mentioned, there is increased oxidative stress in the hair follicle with aging. With aging, the ability to clear the reactive oxygen species (ROS) declines and this buildup eventually leads to hair graying. Indeed, studies show a buildup of ROS such as hydrogen peroxide in up to millimolar concentrations in white hair shafts with almost absent expression of enzymes that repair oxidized protein residues. Without these repair enzymes, there is a loss of tyrosinase enzyme function in melanocytes, and a decline in melanocyte number, leading to a loss of pigment in hair (Trueb 2009). 

Genetic factors are also heavily involved. For example Asian and African people have later onset and less grey hair than Caucasians. Environmental factors have been shown to drive oxidative stress as well including UV rays, pollution, smoking, nutritional deficiency, emotional factors, and inflammation (Kumar et al. 2018, Villani et 2022). For example, studies show smokers are at increased risk of earlier hair graying than nonsmokers (Villani et al. 2022). 

This is why graying hair is a near universal feature of aging but sometimes may happen at a young age which is called premature aging. In men, graying first occurs in the temples and sideburns, whereas in women, it is first noticed at the boundaries of the scalp. Rapid progression of graying usually occurs in the fifth decade of life. 

Unless the cause is from rare nutritional deficiencies, gray hair has no reliable treatment. Though there have been some promising findings in animal models, results in humans have been disappointing (Takekoshi et al 2013). Hence, save your money on any serum or supplement that claims to reverse graying. Those who want to restore hair color usually just take a trip to the salon to get their hair colored (Kumar et al. 2018).

Oxidative stress will also affect hair quality as it has been linked to decreased keratin associated proteins and lipid peroxidation in the hair shaft. This leads to hair that is less shiny and more brittle (Liang et al. 2023). 

Reduced blood flow through dermis with age

Dermal microcirculation is essential for hair maintenance. It is important for delivery of growth factors, nutrients, cytokines, other bioactive molecules, and for removing waste metabolic products. During anagen, there is high metabolic activity of hair follicle matrix cells and an insufficient blood supply leads to hair follicle diseases. Vascular endothelial growth factor (VEGF) regulates angiogenesis and hair follicle size (Bassino et al. 2020). 

Blood flow to the dermis decreases with age. Other factors such as cigarette smoking also causes changes in the microvasculature of the dermal hair papilla. These changes can have negative consequences for hair including thinning and greying (Trueb 2009). 

Scalp massage is thought to help increase blood flow to hair follicles. At least one study indicates an increase in hair thickness with scalp massage and changes in gene expression in DPCs. Other agents such as minoxidil or caffeine likewise are thought to improve hair thickness in part via their effects on blood flow (Natarelli et al. 2023). 

Hair follicle and Skin ECM changes with aging and its effects on hair thinning

Hair follicle and skin aging is associated with a loss of extracellular matrix (ECM) integrity with aging. ECM loss can contribute to premature shedding. ECM loss also leads to elevated stiffness in the basement membrane which deactivates HFSCs (Jang et al. 2023). 

It is well known we lose many of the structural proteins in the ECM with aging including collagen, elastin as well as hydration boosting glycosaminoglycans. Photoaging accelerates this process and also leads to elastosis, a condition where degraded elastin molecules accumulate. Solar elastosis can precede hair thinning and decreases in hair diameter. Bald regions of the scalp often show signs of solar elastosis. This suggests UV skin damage can accelerate balding in those with androgenic alopecia (Trueb 2009).

Scalp massage is thought to help increase blood flow to hair follicles. At least one study indicates an increase in hair thickness with scalp massage and changes in gene expression in DPCs. Other agents such as minoxidil or caffeine likewise are thought to improve hair thickness in part via their effects on blood flow (Natarelli et al. 2023). 

Hair follicle and Skin ECM changes with aging and its effects on hair thinning

Hair follicle and skin aging is associated with a loss of extracellular matrix (ECM) integrity with aging. ECM loss can contribute to premature shedding. ECM loss also leads to elevated stiffness in the basement membrane which deactivates HFSCs (Jang et al. 2023). 

It is well known we lose many of the structural proteins in the ECM with aging including collagen, elastin as well as hydration boosting glycosaminoglycans. Photoaging accelerates this process and also leads to elastosis, a condition where degraded elastin molecules accumulate. Solar elastosis can precede hair thinning and decreases in hair diameter. Bald regions of the scalp often show signs of solar elastosis. This suggests UV skin damage can accelerate balding in those with androgenic alopecia (Trueb 2009).

Autoimmune, Drug Induced etc.

Autoimmune disorders such as Alopecia Areata (AA) can also lead to hair loss and usually strikes during the early adult phase of life. Lifetime prevalence is 1.7% in both men and women (Rinaldi et al. 2019).

Frontal Fibrosing Alopecia is a scarring alopecia that involved the frontotemporal hairline and eyebrows. It is often found in postmenopausal females with mean onset of 60 years old. In this condition, immune cells gather around outer root sheaths and there is scarring around the hair follicles (Villani et al. 2022). 

Many drugs can also induce hair loss. In drug-induced telogen effluvium, hair loss is evident 2-4 months after starting treatment and is temporary as it disappears with drug discontinuation (Villani et al, 2022).

Hypo- and hyperthyroidism can also cause telogen effluvium and reversible diffuse hair loss. Dietary deficiencies in essential amino acids histidine, leucine, and valine and non-essential amino acids alanine and cysteine can also lead to hair loss (Natarelli et al. 2023).

Chemotherapy can lead to hair loss. Scalp cooling is a technique which decreases the delivery of cancer fighting drugs to the scalp, mitigating chemotherapy-induced hair loss (Natarelli et al. 2023).

FDA approved treatments for  hair loss

A. Drug Treatments for Androgenic Alopecia

For androgenic alopecia, topical minoxidyl (for men and women) and oral finasteride (Propecia) (for men only) are the only FDA approved prescription medications. 

Minoxidyl relaxes blood vessels and increases blood flow to increase hair follicle size. Additionally, minoxidyl is an anti-inflammatory and an anti-androgen. However, there can be contact dermatitis for minoxidyl including skin itching (Ohn et al. 2019, Naterelli 2023). For males, a topical 2-5% solution or 5% foam used twice daily can improve or prevent the progression of androgenic alopecia. For women, a 2% solution or 5% foam once daily is recommended. These recommendations are based on positive clinical studies (Villani et al. 2022). About 60% of males respond to topical minoxidyl treatment (Liang et al. 2023).

Finasteride inhibits 5-alpha reductase, the enzyme that converts testosterone into DHT. Studies show 99% of men with male pattern baldness respond positively to finasteride (Natarelli et al. 2023). However, continuous use is necessary as hair regrowth will be reversed when the treatment in stopped (Liang et al. 2023). Dutasteride is another 5-alpha reductase inhibitor that is prescribed off-label. 

There are some negative side effects from these 5-alpha reductase inhibiting drugs such as sexual dysfunction and depression as well as a potential increased risk of prostate cancer (Villani et al. 2022, Liang et al. 2023). 

B. Drug Treatments for Androgenic Disorder Related Alopecia

For women, androgenetic alopecia along with hirsutism (beard) and acne may actually be due to an androgenic disorder. 90% of cases are due to polycystic ovary syndrome. This condition may be treated with estrogen and progestin combination pills. The reason this works is that estrogen and progestin can enhance gonadotropin suppression of ovarian androgen secretion. Cyproterone acetate and spironolactone can also be given as anti-androgens in this population (Zouboulis 2007). 

C. Light Therapy for Alopecia

Light therapy also known as photobiomodulation therapy (PBMT) or low level laser therapy (LLLT) is actually an FDA-approved treatment for hair loss. They do not require a prescription and several devices have shown efficacy.

Red light can penetrate the scalp and be absorbed by enzymes in the mitochondia of hair follicles so that they function better. This increases growth factors and blood flow and prolongs the anagen growth phase. For more in depth information, click this link to our Science blog writeup on this topic (link here to Shedding light on hair growth).

D. Hair Transplantation

Hair transplantation therapy can also be employed to help treat bald areas. However, since these hair follicles are still subject to the aged skin environment and hormonal factors, they are subject to some of the same factors that led to hair loss (Jang et al. 2023).

Non-prescription topical scalp actives that can improve hair thickness and density

Many topicals are not FDA approved but have shown efficacy in studies. These include anti-fungals such as Ketoconazole which is a cortisol inhibitor and partly through this inhibition, it can help increase hair density and prostaglandins such as bimatoprost and latanoprost which are popular in eyelash growth serums (Naterelli et al. 2023).

Here we go over the evidence supporting modern topicals that use actives such as peptides, growth factors, caffeine, vitamins, and botanicals which have been shown in studies to achieve clinical results. Where relevant, we detail the actives found in our Full Follicle line (learn more).  

A. Peptides (Acetyl Tetrapeptide-3)

Peptide Acetyl tetrapeptide-3 can be found in lash, brow, and hair growth serums. In lash and brow serums, they are often the only active. In the Full Follicle line, Acetyl tetrapeptide-3 is just one of 14 actives. 

Acetyl tetrapeptide-3  stimulates dermal papilla cells to increase hydroxyproline, collagen type 3 and laminin production for better ECM integrity and better hair anchoring to reduce shedding as well as increased hair follicle size. Treatment with acetyl tetrapeptide-3 has been shown to stimulate hair growth and allows hair length to increase compared to no treatment.

In a clinical study of 32 patients with mild to moderate androgenic alopecia, acetyl tetrapepetide-3 combined with ginseng extracts and biochanin A demonstrated comparable efficacy at 24 weeks to 3% minoxidil in increasing terminal hair counts (8.3% compared to 8.7%) (Lueangaran and Panchaprateep 2020). 

In another industry-sponsored clinical study, Acetyl tetrapeptide-3 in combination with red clover extract was found to boost the percent of hair follicles in anagen by 15% and decrease hair follicles in telogen in by 52% compared to placebo after 4 months of daily application in lotion form. This boosted hair density. It was found to have similar benefits in rinse-off form (shampoo and conditioner) as well (Capixyl). 

B. Growth factors and Platelet Rich Plasma (PRP)

The Full Follicle lines uses a growth factor complex of five growth factors (EGF, aFGF, IGF-1, VEGF, bFGF) derived from vegan lab-derived sources. 

A diverse array of growth factors regulate the stages of hair growth. Growth factors such as epidermal growth factor (EGF) have been found to operate like a biological switch that turns on hair follicle growth to mark the beginning of anagen. Then turn off to mark the end of anagen (Mak and Chan 2002). Deficiency of insulin-like growth factor 1 (IGF-1) is implicated in androgenic alopecia where it is regulated by androgens. It regulates hair growth and balding scalp follicles secrete significantly less IGF-1 than non-balding scalp follicles (Trueb 2018). 

During anagen, levels of fibroblast growth factor (FGF) and insulin-like growth factor (IGF-1) also increase through a B-catenin signaling pathway which stimulates proliferation of epithelial cells. Another signaling pathway (via ERK) also activates cell growth and vascular endothelial growth factor (VEGF) which is also involved in angiogenesis has been found to regulate the ERK pathway to stimulate the proliferation of dermal papillae cells (Ohn et al. 2019). Due to synergies between growth factors, a combination of growth factors rather than a singular one is more effective (Krane et al. 1991).

Platelet rich plasma (PRP) is one popular route by which these growth factors have been delivered to hair follicles. This is in part because PRP is naturally rich not only in platelets, but also in several growth factors found in plasma. Typically, PRP is used as a blood transfusion product to treat thrombocytopenia. However, it has become popular for ‘off-label’ usage in sport medicine, regenerative medicine, aesthetic medicine and hair loss treatment (Paichitrojjana and Paichitrojjana 2022). The growth factors in PRP stimulate the development of new follicles and neovascularization. Clinical studies have shown increased hair density and diameter in men, and an increase of hair diameter in women (Natarelli et al. 2023).

However, PRP therapy is costly and time consuming as well as being human sourced. For this reason, topical serums that contain synthesized version of growth factors have been developed. Synthesized versions of these growth factors aim to be bioequivalent to natural ones (e.g. sh-oligopeptide-1 is bioequivalent to IGF-1) and this has made growth factors more widely available for cosmetic purposes. There are questions as to whether these synthetic versions mimic the active version of these growth factors (Martinez-Carpio et al. 2023). 

However, a clinical study using synthesized growth factors found they could be used to treat the Alopecia Areata and partially mimic PRP treatment (Rinaldi et al. 2019). Further, clinical studies using synthetic growth factors including epidermal growth factor (EGF), fibroblast growth factor (FGF), insulin-like growth factor (IGF-1) and vascular endothelial growth factor (VEGF) been used either alone or together to treat Androgenic Alopecia (Castro et al. 2012, Kapoor et al 2020). Often these growth factors are injected into the dermal layer of the scalp to prevent hair loss and stimulate hair growth. They are also used to stabilize hair after a hair transplant.  Synthetic growth factors have also been shown to promote hair growth in animal models (Choi et al. 2018).

Industry-sponsored clinical studies using a topical mixture of 5 different synthesized growth factors (sh-Polypeptide-1 /IGF-1, sh-oligopeptide-2 /bFGF, sh-Polypeptide-9/VEGF, sh-Oligopeptide-10/EGF, sh-Polypeptide-11/aFGF) demonstrated decreasing scalp sensitivity and increasing hair thickness after 4 weeks of regular use, with an even greater benefit after 30 weeks of usage. Corresponding in-vivo and ex-vivo studies demonstrate that application of this mixture increased cell proliferation in hair dermal papillae along with corresponding increases in gene and protein expression, as well as greater elongation of the hair shaft (Bio-placenta Hair). 

C. Caffeine

Caffeine counteracts DHT induced miniaturization of the hair follicles and is included in our Full Follicle line.

Caffeine can benefit those with androgenic alopecia. Caffeine inhibits phosphodiesterase and increase cAMP levels promoting cell proliferation. This is thought to be the mechanism by which it counteracts DHT induced miniaturization of the hair follicles. In one in-vitro study using scalp hair follicle biopsies from male subjects, it was found that while testosterone suppressed growth, caffeine stimulated hair follicle growth. Further, caffeine counteracted the negative effects of testosterone on the hair follicle (Fischer et al. 2007).

Clinical studies show caffeine can penetrate into hair follicles after topical application. Topical caffeine was found to be more effective than 5% minoxidyl in men with androgenic alopecia, and in women, a shampoo with caffeine was found to significantly reduce hair loss (Bansal et al. 2012, Bassino et al. 2020). 

D. Vitamins

Vitamins are crucial to healthy skin and hair. For example, scurvy from Vitamin C deficiency and pellagra from Vitamin B3 deficiency historically led to skin issues and hair loss. Indeed, many of the best and most proven anti-aging ingredients for skin are vitamins such as Vitamin A (retinoids), Vitamin B3 (Niacinamide) and Vitamin C. The Full Follicle line contains panthenol (Vitamin B5) and biotin (Vitamin B7).

Deficiencies in B vitamins beyond B3 including B2 (riboflavin), B7 (biotin), B9 (folate), and B12 have also been associated with hair loss. However, dietary deficiencies in these vitamins are extremely rare in the US and dietary supplementation usually does not improve thinning hair. The exception is biotin deficiency which can occur in pregnant woman with some studies finding up to 50% of pregnant women deficient in biotin. Hence, biotin is commonly found in hair growth products (Almohanna et al. 2019).

Vitamin B5 (panthenol) deficiency is not associated with hair loss. However, studies show benefits of panthenol supplementation for aging related hair thinning. One such study showed that this could be because it helps the survival of hair dermal papilla cells and outer root sheath cells. Panthenol reduced markers for apoptosis (cell death) and senescence (aging) in aged and telogen hair follicles. Panthenol also triggered or elongated the anagen phase by stimulating anagen-inducing factors, B-catenin and versican, and increased VEGF growth factor expression (Shin et al 2021). 

Panthenol is also common in hair products because it can both coat the hair shaft forming a protective film and penetrate the hair shaft where it strengthens hair. Panthenol also has well known skin benefits.

Other vitamins and minerals whose deficiency is linked to hair loss includes Vitamin D and Iron (with Vitamin C) and oral dietary supplementation is recommended in this cohort (Almohanna et al. 2019).

E. Botanicals and phytocompounds

Botanical plant extracts and the phytocompounds they contain are known to have multiple properties that are beneficial to hair follicle health due to anti-inflammatory and antioxidant activity. This can help alleviate some of the chronic inflammation and oxidative stress than can lead to decreased activity in the hair follicle (Deng et al. 2022). Furthermore, some will also reduce hair fallout and stimulate hair growth through other additional mechanisms.

The Full Follicle line contains Swiss apple stem cells, Red Clover, Rosemary, Ginseng and Eucalyptus, along with Green tea, Grapeseed and Aloe. 

Certain apple species contain procyanidins which are powerdul antioxidants and anti-inflammatories that improve hair density, weight, and keratin content (Bassino et al. 2020). Procyanidin B-2 has been clinically shown to improve hair density in androgenic alopecia compared to placebo (Nateralli et al. 2023). These procyanidin actives are often collected via plant stem cells from the Malus Domestica (Swiss) Apple. Plant stem cells are a new way of harvesting actives in botanicals in large amounts in a cost-effective, environmentally friendly way. 

Swiss apple stem cell extract has been shown to improve the health of hair follicles and keep them in the anagen phase (growth phase) and out of the catagen phase (dormant phase). In an industry sponsored clinical study, daily application of a topical solution of stem cell extract reduced hair shedding by 34% after one month of treatment, and by 41% after 2 months leading to a visible improvement in hair density (PhytoCellTec). 

Red clover (Trifolium pratense) is a botanical found to help with androgenic alopecia. It contains biochanin A, a phytoestrogen, which inhibits 5-a-reductase activity (Skulj et al. 2019). It is synergistic with acetyl tetrapeptide-3 and in this combination has been found to increase hair thickness and density (Capixyl). 

Rosemary is a botanical renowned in traditional medicine. Rosemary is thought to increase hair growth by stimulating microcapillary perfusion and studies show improved blood circulation and vascularity induced by rosemary helps hair follicle regeneration similarly to minoxidyl (Bassino et al. 2020). Clinical studies show comparable efficacy between rosemary and minoxidyl (Naterelli et al. 2023).

Ginseng (Panax Ginseng) is a traditional Chinese remedy which contains saponins, polysaccharides, and phenolic compounds that have demonstrated anti-inflammatory, antioxidant, and hepato-protective activities. It is also believed to improve blood flow and vasculature, induce hair anagen and have anti-apoptotic effects on outer root sheath keratinocytes. In one study, topical ginseng plus minoxidyl was found to be more effective than minoxidyl alone in promoting hair growth (Bassino et al. 2020). 

Eucalyptus has long been used in scalp treatments for thinning hair and is believed to act via increased blood circulation. One study found increased growth compared to placebo with eucalyptus scalp treatment in both male and female participants (Mamada et al. 2008). 

Green tea (Camellia sinensis) has many anticancer and antioxidant benefits from polyphenols such as epigallocatechin-3-gallate (EGCG). EGCG stimulates human hair growth via its proliferative and antiapoptotic effects on follicular dermal papillae cells (Bassino et al. 2020). 

Vitis Vinifera (Grape) seed extract contains proanthocyanins which have shown promising results for hair growth. Animal studies show that grape-seed derived proanthocyanins can increase the transition from telogen to anagen and at 3% levels, promoted hair growth to an extent comparable to 1% minoxidyl (Takahashi et al. 1998).

Aloe vera has also been used in traditional herbal preparations for hair growth. It is rich in vitamins A, C, E as well as folic acid and vitamin B12. These vitamins are believed help maintain the strength of scalp skin and hair cell development. However, clinical studies are lacking (Khandagale et al. 2023).

F. Ketoconazole

Ketoconazole is an ingredient in medicated anti-fungal shampoos. It is also a cortisol inhibitor and partly through this inhibition, it can help increase hair density. Studies suggest that continual ketoconazole application is required to maintain this hair regrowth (Natarelli et al. 2023). 

G. Prostaglandins

Prostaglandins such as bimatoprost and latanoprost can promote eyelash hair growth. They are popular in eyelash growth serums. They have also been applied to scalp with positive results for hair density and hair growth (Naterelli et al. 2023). They have however some downsides such as darkening of eyes and skin around the eyes.

Taking care of the hair shaft (the visible part of hair) with proper washing and conditioning

Though all the good stuff that will lead to thicker, denser, fuller hair happens in the living part in the scalp skin, a beautiful head of hair also requires maintenance care of the visible hair shaft. 

Harsh cleansers as well as other hair treatments such as styling, coloring, perming, blow-drying will damage your hair, removing the waterproofing coating and damaging the interior parts of hair leaving it brittle and damaged in appearance. Without proper conditioning, hair is difficult to comb and combing with a lot of friction will also damage hair. Proper cleansing and conditioning should leave hair looking sleek and shiny and easy to comb.

Those who are adherents to the “no-poo” method in which hair is infrequently cleansed have a bit of a point in that harsh shampoos will damage hair and leave it worse overall. However, not washing hair will lead to worse outcomes compared to proper cleansing. Let’s go through all the details now.

Hair shaft structure and sources of damage

Unlike the scalp and the hair follicle within the scalp, the visible part of hair (called the hair shaft) is composed of dead cells. So, it’s hard to say what exactly healthy hair means. 

However, usually, people desire a certain aesthetic appearance of hair that is smooth and shiny, untangled, not static, and not frizzy. Damaged hair will be rough, dull, prone to tangle and frizz, prone to brittleness and breakage, prone to splitting, and prone to static.

The visible hair shaft has three concentric layers: the medulla on the inside, then the cortex, and finally the cuticle on the surface.

The cuticle is a very resistant layer that consists of overlapping cells that are arranges like shingles on the roof. This is the hair’s protective barrier. The cuticle in turn has sublayers of these ‘shingles’: the endocuticle, the exocuticle and the outer epicuticle. The epicuticle is the waterproof hydrophobic lipid layer made of 18-methyleicosanoic acid (18-MEA) that is bonded to the fiber. In other words, it’s not like oil floating on the surface of the hair you can wash off. It is anchored firmly in place and does not easily wash off (Gubitosa et al. 2019).

Nonetheless, repeated washing with harsh shampoos will start to remove these lipids from the epicuticle and slowly, the hair loses its waterproof quality. It will then start to swell from water absorption every time you wet it which then damages the inner parts of the hair. Chemical procedures like hair perms or coloring will also damage the cuticle. If you find your hair hard to comb and comb it roughly, then it is likely that friction forces from brushing and combing are also damaging the cuticle. 

So you want to keep cleansing products relatively mild. This is particularly true if you have chemically treated hair. Finally, you want a conditioner that can restore hair waterproofing to help protect your hair and reverse the damage while also reducing friction during brushing and combing.

The importance of proper cleansing and conditioning of scalp/ hair

Let’s go back to the basics and understand why scalp and hair must be cleansed. 

The hair follicles contain glands that produce sebum, a waxy lipid substance that deposits on the skin and hair surface. Those with oily hair produce a lot of sebum. Sweat glands contribute moisture to the scalp. The scalp is also dark due to the hair covering it. Hence, the scalp is a dark, moist and sebum-rich environment. This provides the ideal growing conditions for microbes like Malassezia, a type of yeast. Without cleansing, your scalp becomes infested with these microbes like Malassezia which then play a role in dandruff and seborrheic dermatitis which is characterized by red, itchy and flaky skin. Folliculitis can also result which is when hair follicles are inflamed and infected. Further, Malassezia oxidizes sebum and these oxidized lipids can be irritating to skin. All this will in turn harm hair growth. Hence, proper cleansing is necessary for scalp health and hair growth.

Prior studies which looked at extreme low wash-frequency conditions in an Antarctic research team and in the International Space Station astronauts found increases in scalp itch and flakes and a dramatic rise in scalp Malassezia levels. Other studies looking at less extreme wash-frequency conditions also still find lower wash-frequency associated with increased prevalence of dandruff and seborrheic dermatitis (Punyani et al. 2021).

One such study conducted by Punyani and colleagues looked at a population of 1500 men and women of Chinese. They found that scalp flaking and self-perceived scalp parameters of dandruff, itch, and dryness were much lower for those who washed at least 5-6 times a week. Next, they had subjects refrain from washing for seven days for one week, and then had them wash every day for another 4 weeks, in this case with a special scalp care shampoo that was also anti-dandruff. Compared to the period when subjects refrained from washing hair for seven days, the scalp of subjects when they washed daily had less oxidized lipids, less flaking and less odor intensity. Further the hair itself had less oxidized sebum and was less greasy. Hence, Punyani and colleagues concluded that frequent washing is beneficial to the scalp and hair, with 5-6 times a week or daily washing achieving the best level of overall satisfaction with hair and scalp.

Keep in mind though that this study only looked at those of Chinese ethnicity who have a specific type of hair. Those with less sebum produced by their scalp may need to wash less frequently.

Everyone has different scalp and hair conditions and so the AAD has different advice based on your hair type, your ethnicity, and how treated your hair is. For those with oily hair, they state you may need to wash hair once a day, but if you have chemically treated hair, your hair may be drier and so they suggest washing less frequently. Further, as you get older, your scalp makes less oil and so you may need to shampoo less. For black hair which has a unique structure, the AAD recommends washing just once a week or every other week (AAD).

Your hair can trap airborne pollutants such as pollen and tobacco smoke as well. Nonetheless, hair washing is actually primarily to wash the scalp of sebum and sweat and control the levels of microbes like Malassezia. This will prevent dandruff and seborrheic dermatitis and folliculitis as well as reduce itch and odor. Hence, shampooing should be primarily concentrated around the scalp with secondary concern for washing hair (AAD). 

Though shampoos also clean hair of sebum, sweat, skin flakes, styling products, and dirt, they can also damage hair leaving it dry, frizzy, and prone to tangle and break. Mild shampoos are meant to create less of this damage. 

Conditioners are meant to coat hair and protect it against future damage, as well as fix any damage, as well as making hair easier to comb. They can additionally serve to beautify the hair (Draelos 2010). Hence, conditioning is meant mainly for the hair and shampoos should always be followed by a conditioner, unless using a specifically formulated 2-in-1 shampoo that simultaneously conditions (typically with a silicone oil called dimethicone).

Picking the right shampoo and conditioner

Hair cleansing requires consideration of both the scalp and the hair. As mentioned, shampoos are primarily meant for scalp and secondarily for hair. So when choosing a shampoo, focus should be on the scalp. The right shampoo for you will thoroughly cleanse your scalp while minimally damaging your hair. Conditioners are mainly meant for the hair and meant to coat and waterproof hair to fix any damage, protect against potential future damage, and make hair easier to comb.

Scalp is of course skin. The amount of oily sebum secreted by each person’s scalp differs from person to person. Some people may have very oily hair after not washing for a day or two, while others may have less sebum and dry hair. Shampoos usually contain a blend of cleansing agents with stronger detergents for oily hair, and milder detergents for dry and damaged hair.

If you tend to have oily hair, you may not necessarily need a stronger cleansing shampoo if you can manage to wash your hair daily. A stronger cleansing shampoo may damage your hair and is less than ideal if you have thinning, permed, color-treated or damaged hair. Hence, we generally recommend a mild shampoo with more frequent washing up to daily for those with oily hair. 

So how are mild shampoos different from harsh and damaging ones? The main difference is the cleansing agents. 

You should avoid any shampoo that contains soaps as a cleansing agent. Soaps are not recommended for hair cleansing for many reasons. First, they can leave behind soap scum when mixed with hard water which is difficult to rinse from hair and scalp. Further, the pH of the scalp is between 4.5 and 6.2 while the pH of hair fibers is around 3.67 and so both the scalp and the hair shaft are naturally acidic and harmed by the alkaline pH of soaps (Cline et al. 2018, Dias et al. 2014).

Shampoos are typically synthetic detergents (syndets) and more specifically, mixtures of syndets. Some syndets are harsher than others. So the other thing to avoid is harsher syndets like sulfates. While sulfates like lauryl sulfates like SLS and SLES are popular in shampoo products, they are harsh cleansers and further have a negative reputation of irritancy. Hence, it is a good idea to avoid sulfates and opt for sulfate-free products. Milder sulfate-free formulas use syndets like ‘isethionates’ or ‘sulfonates’ (Draelos 2010, D’Souza and Rathi 2015, Cline et al. 2018). 

Now to get really nerdy for a second, the main cleansing syndets are anionic surfactants. Sulfates like SLS and SLES, and sulfate-free syndets such as isethionates and sulfonates are all anionic surfactants. Anionic surfactants are good at removing sebum and dirt but can leave a negative charge on the hair surface increasing frizz and friction. This is why other nonionic surfactants (no electrical charge) or amphoteric surfactants which can neutralize charge may be added to shampoo formulas. This is why in most mild shampoos, you will actually find a blend of syndets that includes anionic, nonionic and amphoteric surfactants (Dias 2015, Draelos 2010, Gubitosa et al. 2019, D’Souza and Rathi 2015).

Now those who are drawn to the idea of “natural” cleansing may be drawn to products that contain natural surfactants which are natural saponins found in plants such as sarsaparilla, soapwort, soap bark and ivy agave. In recent times, these have made an appearance in shampoos particular in those from India where soapnut or Reetha, Amla, and Sheekakai have also been used for centuries to wash hair. These herbal saponins alone are generally found to be poor cleansers however. So when you find herbal shampoos touting these ingredients, they are typically mixed with the same syndets you find in non-herbal shampoos (Dias 2015, Draelos 2010, Gubitosa et al. 2019, D’Souza and Rathi 2015).

Solid bar shampoos or dry shampoos have recently become more popular for eco-sustainability reasons. They may include the same syndets such as SLS. Dry shampoos on the other hand may feature baking soda and corn starch which are not detergents. Note that baking soda and corn starch are not a good replacement for a detergent and will not cleanse your scalp nor help maintain your hair quality the way conditioners can. Clay minerals may also be used in hair cleansing products due to good absorption properties. Again though, they are not a good replacement for a detergent (Gubitosa et al. 2019).

Liquid shampoos contain other additives that are good for scalp and hair. Like skin, the hair is more damaged by an alkaline product. Hence, in liquid shampoos, pH adjustors like citric acid may be added to the shampoo. Sequestrant agents are also added to remove minerals from hard water that can lead to scalp scum. Medicated shampoos may also contain ingredients such as tar, salicylic acid, sulfur, selenium sulfide, polyvinylpyrrolidone-iodine complex, chlorinated phenols, or zinc pyrithione. These additions act to remove dandruff, or act as antibacterial, antifungal, or anti-inflammatory agents. These are used for people with scalp problems like seborrheic dermatitis, psoriasis, bacterial or fungal infections. Those with thinning hair may also want a thickening shampoo that contains additional actives such as caffeine, peptides and botanicals that can help stimulate hair growth (Draelos 2010, D’Souza and Rathi 2015).

Our Full Follicle shampoo is a scalp stimulating sulfate-free mild shampoo that is gentle enough to use as often as needed, but still cleanses thoroughly and allows for maximal penetration of scalp actives. It is formulated for thinning, damaged or color-treated hair and contains many of the same actives as the scalp serum including Acetyl Tetrapeptide-3, Growth Factor Complex (5 GFs), Caffeine, Red Clover, Rosemary, Eucalyptus, Panthenol, and Biotin (learn more).

How do conditioners work to repair hair and protect it?

Unfortunately, no matter how mild the shampoo, washing hair basically makes hair rough, That is where conditioners come in. The right conditioners can restore hair waterproofing and help repair damage, while reducing frictional forces and minimizing static electricity, leading to what we identify as beautiful hair.

Conditioners can neutralize the negative charge left by anionic surfactants by adding positive charges (cationic syndets and polymers). Damaged hair also has a negative charge because the inner layers of hair behind the damaged cuticles also carry a negative charge. Conditioners contain cationic molecules that bind to the negatively charged damaged hair. Neutralizing this charge will diminish static, frizz and friction. 

Panthenol (Provitamin B5) is popular in conditioners as it can stick to hair and absorb into the deeper layers of the hair where it acts as a humectant, holding onto water to help keep hair hydrated. Plant oils and butters contain fatty acids which can also penetrate and coat the hair shaft improving its waterproofing. Hence, conditioners restore the cuticle’s waterproofing and the combability of hair using a combination of polymers, oils, and butters/waxes.

Silicones are also in the majority of conditioners and some shampoos due to their ability to coat hair strands and make them shiny as well as frizz-free. There are also 2-in-1 shampoo/conditioners that contain both cleansing and conditioning elements in one product that contain silicones. Popular silicones include dimethicone, cyclopentasiloxane, amodimethicone, phenyl trimethicone, and dimethiconol amongst others. 

However, we believe silicone-free hair products are better for thinning hair or haircare systems with scalp actives. While some prefer the sleek and smooth appearance of silicone-coated hair, some dislike the artificial shine, gloss and slip this gives to hair. They prefer a shine, look and feel to their hair that is more natural. Particular for those who use sulfate-free, mild cleansing that reduces hair damage, silicone coatings may build up on the hair, leading to a heavy, weighed down look and feel. 

For those with thin hair, this may actually lead to hair that is flat and lifeless. Many with curly hair also feel the silicone coating interferes with curl formation and choose to avoid silicones. Further, for those with damaged hair, when looking to fix hair damage with ingredients that absorb into the hair shaft, the silicone coating can prevent absorption of these beneficial ingredients into hair strands and scalp, reducing the ability of hair damage to be fixed from the inside (Dias 2019).

Our Full Follicle conditioner uses a silicone-free system powered by ucuuba and murumuru butters as well as panthenol, biotin and swiss apple stem cells (learn more). 

How to properly use shampoo and conditioner

Shampoo mainly aims to cleanse the scalp of oily sebum and trapped dirt. So apply small amounts of shampoo to each region of the head under the hair and thoroughly cleanse the scalp. Then gently work through the hair to the ends to cleanse the hair. Don’t just apply shampoo to the top of the head as you won’t get it into the whole scalp, and this will lead to more hair tangling as the hair gets washed more than the scalp. 

After rinsing out the shampoo, apply the conditioner through the hair length as conditioner is generally a product that targets hair damage, frizz and friction. It should be applied at mid-lengths and worked through from scalp to ends and gently worked through the hair length focusing on the ends. Leaving it in for a couple minutes before rinsing will give time for moisturizing agents to be absorbed into the hair shaft (Dias 2015).

References

Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A (2019). “The Role of Vitamins and Minerals in Hair Loss: A Review.” Dermatol Ther 9:51-70.

American Academy of Dermatology Association. “Face Washing 101”. https://www.aad.org/public/everyday-care/skin-care-basics/care/face-washing-101

American Academy of Dermatology Association. “How to safely exfoliate at home”. https://www.aad.org/public/everyday-care/skin-care-secrets/routine/safely-exfoliate-at-home

American Academy of Dermatology Association. “Tips for healthy hair”. https://www.aad.org/public/everyday-care/hair-scalp-care/hair/healthy-hair-tips

American Academy of Dermatology Association. “Black hair: Tips for everyday care”. https://www.aad.org/public/everyday-care/hair-scalp-care/hair/care-african-american

Ananthapadmanabhan KP, Moore DJ, Subramanyan K, Manoj M, Meyer F (2004). “Cleansing without compromise: the impact of cleansers on the skin barrier and the technology of mild cleansing.” Dermatologic Therapy 17: 16-25.

Ananthapadmanabhan KP (2019). “Amino-Acid Surfactants in Personal Cleansing (Review).” Tenside Surf Det 56(5): 378-386.

Ayres S (1963). “Rosacea-Like Demodicidosis.” California Medicine 98(6): 328-330.

Bansal M, Manchanda K, Sunder Pandey S (2012). “Role of Caffeine in the Management of Androgenetic Alopecia.” Int J Trichology 4(3): 185-186.

Bassino E, Gasparri F, Munaron L (2020). “Protective Role of Nutritional Plants Containing Flavonoids in Hair Follicle Disruption: A Review.” Int J Molec Sci 21: 523. doi:10.3390/ijmc21020523.

BBC Reel. “There are thousands of mites living on your face.” https://www.youtube.com/watch?v=UZGttZi6L94

Buffoli B, Rinaldi R, Labanca M, Sorbellini E, Trink A, Guanziroli E, Rezzani R, Rodella LF (2014). “The human hair: from anatomy to physiology.” International Journal of Dermatology 53: 331-341.

Castro RF, Azzalis LA, Feder D, Perazzo FF, Pereira EC, Junquieira VBC, Rocha KC, D’A Machado C, Paschoal FC, Gnann LA, Fonseca FLA (2012). “Safety and efficacy analysis of liposomal insulin-like growth factor-1 in a fluid gel formulation for hair-loss treatment in a hamster model” Clin Exp Dermatol 37(8): 909-912.
Chen W, He M, Xie LMM, Li L (2020). “The optimal cleansing method for the removal of sunscreen: Water, cleanser or cleansing oil.” J Cosmet Dermatol 19(1): 180-184.

Choi JM, Lew VK, Kimball AB (2006). “A single-blinded, randomized, controlled clinical trial evaluating the effect of face washing on acne vulgaris.” Pediatr Dermatol 23(5): 421-427.

Choi YM, Choi SY, Kim H, Kim J, Ki MS, An I, Jung J (2018). “TGFB family mimetic peptide promotes proliferation of human hair follicle dermal papilla cells and hair growth in C57BL/6 mice.” Biomedical Dermatology 2:23. https://doi.org/10.1186/s41702-018-0033-8.

Choi YS, Suh HS, Yoon MY, Min SU, Kim JS, Jung JY, Lee DH, Suh DH (2010). “A study of the efficacy of cleansers for acne vulgaris.” J Dermatolog Treat 21(3): 201-205.

Cleveland Clinic. “Demodex (Face Mites).” https://my.clevelandclinic.org/health/diseases/22775-demodex-face-mites

Cline A, Uwakwe LN, McMichael AJ (2018). “No Sulfates, No Parabens, and the ‘No-Poo’ Method: A New Patient Perspective on Common Shampoo Ingredients.” Cutis 101: 22-26.

Coiffard L, Couteau C (2020). “Soap and syndets: differences and analogies, sources of great confusion.” Eu Rev Med Pharmacol Sci 24: 11432-11439.

Cornwell PA (2017). “A review of shampoo surfactant technology: consumer benefits, raw materials and recent developments.” Int J Cosmet Sci 40: 16-30.

Cui J, Shen Y, Li R (2013). “Estrogen synthesis and signaling pathways during ageing: from periphery to brain.” 19(3): 197-209.

Deng Y, Wang M, He Y, Liu F, Chen L, Xiong X (2023). “Cellular Senescence: Ageing and Androgenic Alopecia.” Dermatology 239: 533-541.

Dias MFRG, de Almeida AM, Cecato PMR Adriano AR, Pichler J (2014). “The Shampoo pH can Affect the Hair: Myth or Reality?” Int J Trichology 6(3): 95-99.

Dias MFRG (2015). “Hair Cosmetics: An Overview.” Int J Trichology 7(1): 2-15.

Draelos ZD (2010). “Essentials of Hair Care often Neglected: Hair Cleansing.” Int J Trichology 2(1): 24-29.

D’Souza P, Rathi SK (2015). “Shampoo and Conditioners: What a Dermatologist Should Know?” Indian J Dermatol. 60(3): 248-254.

Ejere HOD, Alhassan MB, Rablu M (2015). “Face washing promotion for preventing active trachoma.” Cochrane Database of Systematic Reviews. Doi: 10.1002/14651858.CD003659.pub4.

Fischer TW, Hipler UC, Elsner P (2007). “Effect of caffeine and testosterone on the proliferation of human hair follicles in vitro.” Int J Dermatol 46: 27-35. 

Gfatter R, Hackl P, Braun F (1997). “Effects of Soap and Detergents on Skin Surface pH, Stratum corneum Hydration and Fat Content in Infants.” Dermatology 195: 258-262.

Gubitosa J, Rizzi V, Fini P, Cosma P (2019). “Hair Care Cosmetics: From Traditional Shampoo to Solid Clay and Herbal Shampoo, A Review.” Cosmetics. 6(13): doi: 10.3390/cosmetics6010013.

Hosokawa K, Taima H, Kikuchi M, Tsuda H, Numano K, Takagi Y (2021). “Running the skin when removing makeup cosmetics is a major factor that worsens skin conditions in atopic dermatitis patients.” J Cosmet Dermatol 20(6): 1915-1922.

Infante MR, Perez L, Pinazo A, Clapes P, Moran MC, Angelet M, Garcia MT, Vinardell MP (2004). “Amino acid-based surfactants.” C.R. Chimie 7: 583-592.

Jang H, Jo Y, Lee JH, Choi S (2023). “Aging of hair follicle stem cells and their niches.” BMB Rep 56(1): 2-9. 

Kapoor R, Shome D, Vadera S, Kumar V, Ram MS (2020). '“QR678 & QR678 Neo Hair Growth Formulations: A Cellular Toxicity & Animal Efficacy Study.” Plast Reconstr Surg Glob Open 8:e2843. doi:10.1097/GOX.0000000000002843.

Khandagale S, Ratnaparkhe C, Sayyad S, Shelar V, Supekar A, Sarukh V (2023). “A review of herbal medications for the treatment of alopecia” IJAPR 11:Suppl 4.

Korting HC, Ponce-Poschl E, Klovekorn W, Schmotzer G, Arens-Corell M, Braun-Falco O (1995). “The influence of the regular use of a soap or an acidic syndet bar on pre-acne.” Infection 23(2): 89-93.

Krane JF, Murphy DP, Carter DM, Krueger JG (1991). “Synergistic effects of epidermal growth factor (EGF) and insulin-like growth factor 1/somatomedin C (IGF-1) on keratinocyte proliferation may be mediated by IGF-1 transmodulation of the EGF receptor.” JID 96(4): 419-424.

Kumar AB, Shamim H, Nagaraju U (2018). “Premature Graying of Hair: Review with Updates.” Int J trichology 10(5): 198-203. 

Li H, liv F, Zhu S, Shin MK, Lu F, Qu J, Hou L (2017). “Epilation induces hair and skin pigmentation through an EDN3/EDNRB-dependent regenerative response of melanocyte stem cells.” Scientific Reports 7:7272. doi:10.1038/s41598-017-07683-x. 

Liang A, Fang Y, Ye L, Meng J, Wang X, Chen J, Xu X (2023). “Signaling pathways in hair aging.” Front Cell Dev Biol 11:1278278. doi: 10.3389/fcell.2023.1278278.

Lueangarun S, Panchaprateep R (2020). “An Herbal Extract Combination (Biochanin A, Acetyl tetrapeptide-3, and Ginseng Extracts) versus 3% Minoxidil Solution for the Treatment of Androgenetic Alopecia: A 24-week, Prospective, Randomized, Triple-blind, Controlled Trial.” J Clin Aesthet Dermatol 13(10): 32-27.

Mak KKL, Chan SY (2003). “Epidermal Growth Factor as a Biologic Switch in Hair Growth Cycle.” The Journal of Biological Chemistry. 278(28): 26120-26126.

Mamada A, Ishihama M, Fukuda R, Inoue S (2008). “Changes in hair properties by Eucalyptus extract.” J Cosmet Sci 59(6): 481-496. 
 
Martin LMM, Mendes MF, Takaoka LE, Martin MM, Martin BM (2010). Dermatosis Neglecta: a report of two cases. An Bras Dermatol 85 (2): 217-220.

Martinez-Carpio P (2023). “Topical application of sh-oligopeptide-1 and clinical trials with cosmetic preparations: risk or fraud?” Cutaneous and Ocular Toxicology. doi.org/10.1080/15569527.2023.2234020

Mijaljica D, Spada F, Harrison IP (2022). “Skin Cleansing without or with Compromise: Soaps and Syndets.” Molecules 27: https://doi.org/10.3390/molecules27062010.

Moran MC, Pinazo A, Perez L, Clapes P, Angelet M, Garcia MT, Vinardell MP, Infante MR (2004). “Green amino acid-based surfactants.” Green Chem 6: 233-240.

Natarelli N, Gahoonia N, Sivamani RK (2023). “Integrative and Mechanistic Approach to the Hair Growth Cycle and Hair Loss.” J Clin Med. 12: 893. doi.org/10.3390/jcm12030893.

Ohn J, Kim KH, Kwon O (2019). “Evaluating hair growth promoting effects of candidate substance: A review of research methods.” Journal of Dermatological Science 93: 144-149.

Paichitrojjana A, Paichitrojjana A (2022). “Platelet Rich Plasma and Its Use in Hair Regrowth: A Review.” Drug, Design, Development and Therapy 16: 635-645.

Price VH. “Testosterone Metabolism in the Skin. A Review of Its Function in Androgenetic Alopecia, Acne Vulgaris, and Idiopathic Hirsutism Including Recent Studies With Antiandrogens.” Arch Dermatol 111: 1496-1502.

Punyani S, Tosti A, Hordinsky M, Yeomans D, Schwartz J (2021). “The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions.” Skin Appendage Disorders. 7: 183-193.

Rather PA, Hassan I (2014). “Human Demodex Mite: The Versatile Mite of Dermatological Importance.” Indian J Dermatol. 59(1): 60-65.

Rinaldi F, Marzani B, Pinto D, Sorbellini E (2019). “Randomized controlled trial on a PRP-like cosmetic, biomimetic peptides based, for the treatment of alopecia areata.” Journal of Dermatological Treatment 30(6): 588-593.

Saha A, Seth J, Sharma A, Biswas D (2015). “Dermatitis Neglecta – A Dirty Dermatosis: Report of Three Cases.” Indian J Dermatol. 60 (2): 185-187.

Schulster M, Bernie AM, Ramasamy R (2016). “The role of estradiol in male reproductive function.” Asian Journal of Andrology 18: 435-330.

Shin JY, Kim J, Choi YH, Kang NG, Lee S (2021). “Dexpanthenol promotes cell growth by preventing senescence and apoptosis in cultured human hair follicle cells.” Curr Issues Mol Biol 43: 1361-1373.

Skulj A, Poljsak N, Glavac N, Kreft S (2020). “Herbal preparations for the treatment of hair loss.” Arch Dermatol Res 312(6): 395-406. 

Takagi Y, Kaneda K, Miyaki M, Matsuo K, Kawada H, Hosokawa H (2015). “The long-term use of soap does not affect the pH-maintenance mechanism of human skin.” Skin Res Technol 21(2): 144-148.

Takahashi T, Kamiya T, Yokoo Y (1998). “Proanthocyanidins from Grape Seeds Promote Mouse Hair Follicle Cells In Vitro and Convert Hair Cycle In Vivo.” Acta Derm Venereol 78: 428-432.

Takekoshi S, Matsuzaki K, Kitatani K (2013). “Quercetin Stimulates Melanogensis in Hair Follicle Melanocytes of the Mouse.” Tokai J Exp Clin Med 38(4): 129-134.

Thornton MJ (2002). “The biological actions of estrogens on skin.” Exp Dermatol 11: 487-502.

Trueb RM (2009) “Oxidative Stress in Ageing oh Hair.” Int J Trichology 1(1): 6-14. 

Trueb RM (2017). “Further Clinical Evidence for the effect of IGF-1 on Hair Growth and Alopecia.” Skin Appendage Disord 4(2): 90-95.

Villani A, Ferrillo M, Fabbrocini G, Ocampo-Garza SS, Scalvenzi M, Ruggiero A (2022). “Hair Aging and Hair Disorders in Elderly Patients.” Int J Trichology 14(6): 191-196.

West S, Munoz B, Lynch M, Kayongoya A, Chilangwa Z, Mmbaga BBO, Taylor HR (1995). “Impact of face-washing on trachoma in Kongwa, Tanzania.” Lancet 345: 155-158.

Zouboulis CC Degitz K (2004). “Androgen action on human skin - from basic research to clinical significance.” 13(Suppl4): 5-10.

Zouboulis CC, Chen WC, Thornton MJ, Qin K, Rosenfield R (2007). “Sexual Hormones in Human Skin.” Horm Metab Res 39:85-95.