What is Laser or Light Therapy for Hair Growth?
The scientific term for this therapy is low-level laser- or light-therapy, or LLLT. LLLT includes red light in the visible spectrum as well as near-infrared light.
There are many similar sounding terms — LEDs or lasers, low-level laser light therapy, red light therapy for hair growth — it's all basically the same thing.
If you expose hair follicles to a low level of red light, they are stimulated to grow. And this has been proven in multiple double-blind sham-controlled trials.
It has long been known that LLLT can promote tissue repair and has beneficial effects for wound healing, nerve regeneration, and joint pain relief (Avci et al. 2014).
Why Red Light?
Red light has the longest wavelength in the visible light spectrum, and it is believed the longer wavelength can penetrate deep into the scalp cells better.
Near-infrared light also works — near-infrared light is just light that is a little longer in wavelength than red light, so it is believed it can penetrate even deeper. However, no comparison studies have been conducted between the two to say one is better than the other (Pillai and Mysore 2021).
How Do We Know LLLT Works?
Like so many medical breakthroughs, the benefit of light on hair growth was found by accident.
In 1967, a Hungarian physician named Endre Mester was investigating whether a low-power ruby laser that emitted red light at wavelength 694nm could be carcinogenic. He shaved his mice as part of his experiment. To his surprise, the laser did not cause cancer, but instead improved the animal's hair growth (Avci et al. 2014).
What. a. Nice. surprise.
Another observation that made people realize the value of light for hair growth was something called "Paradoxical Hypertrichosis." This is actually an unwanted side effect that can occur when people try to use laser to remove hair.
In laser hair removal, the hair is stimulated with a powerful light and the melanin in your hair absorbs that light energy to convert it into enough heat to damage the hair follicle. That's how laser hair removal works.
But in cases where not enough light is absorbed to damage the hairs, the hairs actually can grow stronger in density and thickness in response to the light and heat (Avci et al. 2014).
How Does LLLT Work?
Let's take a quick detour into the life of hair: hair follicles undergo repetitive lifecycles and each cycle has three stages.
LLLT is thought to stimulate re-entry into anagen from telogen, prolong the duration of anagen, and prevent premature catagen development. In other words, it keeps more hair cells for longer in the growth phase — leading to increases in hair density, hair diameter, and a decrease in hair shedding.
This sounds awesome! But how exactly does LLLT work to do this? The answer is that no one really knows exactly. But several mechanisms have been investigated.
So there are a number of possibilities for why laser and LED therapies can help maintain a fuller head of hair — but we don't know for certain how they work.
Lasers vs. LEDs vs. Red Light
Lasers and LEDs are just two different types of light sources. You'd use a laser if you need a focused beam to travel distance — like laser pointers, or in hair removal to specifically heat a single follicle. LEDs, on the other hand, emit more diffused light beams.
Online you may see debates about lasers versus LEDs. But in the context of hair growth, the main point is simply to deliver steady illumination of red light over the scalp at a low power. That distinction matters less than you'd think.
High power lights can damage hair follicles, and moderate power light can actually be inhibitory. That's why low power light therapy is used — and why more isn't better.
Specifically, for low-level light therapy, power density is between 3 to 90mW/cm² with each treatment session lasting 15–20 minutes at a time, three times a week, for 6 months in duration. Individual devices will have their own instructions — follow those.
In a meta-analysis comparing treatment groups, those who received less than 60 minutes of LLLT per week had better hair growth than those who received more than 60 minutes. More is not better here — just follow the instructions and don't go overboard.
Most studies have been conducted with lasers. None have been conducted with LEDs alone, but some studies have used helmets that contain both lasers and LEDs (Pillai and Mysore 2021, Lanzafame et al. 2013, 2014). For practical home use, both formats have shown results.
Helmet vs. Comb
Currently both comb-type and helmet-type home-based LLLT systems are available. In meta-analyses that compare the two formats, no differences in effect sizes were found — suggesting both are about equally effective (Liu et al. 2019). Choose whichever format fits your lifestyle and budget.
LLLT vs. Minoxidil
In one study, researchers tested three treatment scenarios: a light therapy helmet by itself, 5% topical minoxidil by itself, and the combination of both light therapy and minoxidil.
Both LLLT and minoxidil were similarly effective when used alone — but the combination led to the best effects (Pillai and Mysore 2021). This indicates LLLT helmets can be about as effective as minoxidil, and you can double up for an even greater hair growth boost.
Who Does It Work For?
Keep in mind that LLLT combs and helmets have only been shown to work in clinical trials for those with androgenetic alopecia — also known as male pattern baldness.
The other FDA-approved treatments for androgenic alopecia include minoxidil and finasteride. Hair transplants are the other treatment alternative.
In theory, LLLT may work for other types of hair loss, but it hasn't yet been subjected to clinical trials for conditions beyond male pattern baldness — although it has been tested in animal models.
So if you have a type of hair loss other than androgenic alopecia, LLLT may still work for you — the evidence is just less established in humans so far.
How Long Does Laser Hair Growth Last?
Just like minoxidil (Rogaine) or finasteride (Propecia), any hair growth benefits you obtain with LLLT will last only as long as you maintain treatment. This doesn't mean you will lose all the hair growth all at once — hair will slowly revert back to the normal baseline as it sheds when you stop using the LLLT.
Light therapy for hair growth is legitimate, science-backed, and works for both men and women with androgenetic alopecia. Choose an FDA-cleared device, follow its instructions carefully, don't overdo sessions, and consider combining it with minoxidil for best results. Consistency over time is what gets results.
- Avci P, Gupta GK, Clark J, Wikonkal N, Hamblin MR (2014). "Low-Level Laser (Light) Therapy (LLLT) for Treatment of Hair Loss." Lasers Surg Med. 46(2): 144–151.
- Lanzafame RJ, Blanche RR, Bodian AB, Chiacchierini RP, Fernandez-Obregon A, Kazmirek ER (2013). "The growth of human scalp hair mediated by visible red light laser and LED sources in males." Laser in Surgery and Medicine. 45(8): 487–495.
- Lanzafame RJ, Blanche RR, Chiacchierini RP, Kazmirek ER, Sklar JA (2014). "The Growth of Human Scalp Hair in Females Using Visible Red Light Laser and LED Sources." Lasers in Surgery and Medicine. 46: 601–607.
- Liu K, Liu D, Chen Y, Chin S (2019). "Comparative effectiveness of low-level laser therapy for adult androgenic alopecia: a system review and meta-analysis of randomized controlled trials." Laser Med Sci. 6: 1063–1069.
- Pillai JK, Mysore V (2021). "Role of Low-Level Light Therapy (LLLT) in Androgenetic Alopecia." J Cutan Aesthet Surg 14(4): 385–391.
