This article on hot flashes is part of our series about post-menopausal skin.

Many of you may be approaching menopause or are early into menopause and may start to experience random moments of feeling intense heat. Your skin gets hot and reddened and you start sweating, but soon after, you may get shivers and chills.

This is a hot flash, and it makes no sense right?! What is going on here?

Surprisingly, it really has nothing to do with your skin even though it feels like it.

It actually has everything to do with your brain and a specific region on your brain called the hypothalamus. The hypothalamus regulates things like heart rate, sleep, thirst, hunger - and body temperature. Basically, it automatically regulates things to keep you alive so that you don’t have to think about them constantly -- As a part of what’s called the autonomic nervous system.

The brain has a lot of estrogen receptors. So when the levels of estrogen start to drop during menopause, there are changes in the messages between the cells in the brain. As a result, parts of the brain like the hypothalamus start to misinterpret just how hot your body is.

After a few years of menopause, your hypothalamus resets itself over time and hot flashes go away. Although this isn’t the best news since you may experience discomfort for a few years, it’s still comforting to know that it will eventually go away.

In the meantime, if hot flashes are mild, you can make some lifestyle changes like quitting smoking or reducing anxiety, which are good for general health anyways, to reduce hot flashes. And practices like paced breathing exercises also help a lot.

Or in moderate to severe cases, hot flashes can be treated with estrogen replacement therapy, or drugs that work on the brain such as certain SSRIs and SNRIs that you usually think of for depression. The same hormone that can trigger anxiety and depression plays a role in body temperature regulation.

That was the quick summary. And we’re now going to go in depth on why and how hot flashes happen and what you can do to treat them.  To give you a quick heads up, this article is going to be much more about the brain than skin. 

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This content is provided as part of our commitment to bringing science-based information to the public, and it is intended to offer general scientific background on the topic. However, health is complex, and individual cases can vary significantly. We strongly encourage you to consult with a healthcare provider who can diagnose and prescribe treatments specifically tailored to your needs.

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Why and how do hot flashes happen?

So typically, on a very hot day, as your body temperature rises, the blood vessels in your body - particularly hands, arms, feet and legs, the non-core parts - dilate in response, something called peripheral vasodilation.

That's why your rings and bracelets feel tighter during the summer compared to the winter.

As the warm blood rushes to your fingers and toes, the temperature increases in the peripheral areas of your body while your core body temperature drops. Your body heat dissipates through your skin to the outside of your body. This is a normal response to keep your body from overheating.

However, in hot flashes your body becomes overly sensitive to little changes in heat, and even if your core body temperature is still in the right zone, your body will respond as if you are very hot and proceed with all the procedures involved in rapidly dumping heat - peripheral vasodilation, profuse sweating, and sensations of intense heat on the skin and on your face and chest.

And because your body just dumped a ton of heat even though you were not really over-heating, then you get chills and shivering after the hot flash subsides.

While it may feel like a skin condition, and you can see the effects on the skin as your face and chest become red from the rush of blood, hot flashes are actually related to changes in the part of the brain that regulates body temperature, due to the changes in levels of estrogen which is a hormone that has a large effect on the brain.

Over time, your brain adjusts to the lowered amounts of estrogen and hot flashes disappear on their own a few years into menopause for most women.

Hot flashes and your brain

The exact cause of hot flashes is not well understood, but they are thought to be related to changes in the body's estrogen levels and the way they affect the parts of the brain in charge of body temperature regulation.

This is how it might play out:

During perimenopause and menopause, the levels of estrogen and progesterone decline sharply. These are two hormones produced by the ovaries.

Estrogen has effects on the parts of the brain that regulate body temperature, and the changes in estrogen levels may disrupt the body's ability to regulate temperature properly.

This hormonal disruption can lead to a brain that suddenly over-reacts to even
The chills that happen along with the hot flashes are due to this over-reaction, with your body being cooled when it was not necessary, resulting in a lowered core body temperature, and shivering occurs when your body now tries to get your core body temperature back up to a normal temperature (Freedman 2014, Bansal et al. 2019).

This over-reaction to small changes in heat and subsequent inability to properly control your core body temperature is all due to changing hormonal levels and their influence on neurotransmitters in the hypothalamus, a region of your brain that controls functions like your body temperature.

You may have heard of neurotransmitters in the context of mental health. Neurotransmitters are chemicals released by the cells of your brain, called neurons, that allow the cells of your brain to communicate with one another. No one fully understands how neurotransmitters work, but drugs that act on neurotransmitters can often be helpful when dealing with mental health.

For example, people might take Prozac, which is a drug that affects the levels of a neurotransmitter called serotonin and this helps them deal with depression and anxiety.

Others might do better with a drug like Effezor, which is a drug that affects the levels of a neurotransmitter called norepinephrine as well as levels of serotonin, and this might help them deal with depression and anxiety.

Serotonin and norepinephrine can also influence each other, and so these two neurotransmitters can be linked.

There is also a dark side to affecting neurotransmitters in an uncontrolled way like in the case of drugs of abuse. Drug abuse of cocaine and methamphetamine affect levels of a neurotransmitter called dopamine.

Now the neurons of your brain also have estrogen and progesterone receptors. And your brain responds to changes in levels of these hormones.

That’s why before you get your period, when estrogen and progesterone levels change rapidly, you may notice mood swings or changes in energy levels. This is the basis of PMS or premenstrual syndrome.

Estrogen drops before your period and this leads to a drop in the neurotransmitter serotonin and this affects your mood, energy, and irritability.

Everyone experiences PMS differently. Some women may get such severe PMS that it becomes a disorder called PMDD or premenstrual dysphoric disorder. But then some women may barely notice PMS symptoms.

In the same way, every woman will experience hot flashes differently and the basis of hot flashes is similar to the basis of PMS, which is hormone levels affecting neurotransmitter levels.

In the case of hot flashes, the dropping of estrogen levels affect serotonin and norepinephrine levels enough to affect the hypothalamus, which is the part of your brain which regulates temperature. Hypothalamus drives many other things as well, but in this video we’ll focus on just the body temperature regulation part.

So, this is the crux: As the level of estrogen drops in your body, it affects the levels of serotonin and norepinephrine.

This change causes your hypothalamus to become extremely sensitive, causing it to overreact to even minor changes in body temperature.

This can be compared to a broken thermostat that turns on the air conditioning even when the room is already at a comfortable temperature, resulting in the room becoming too cold. Although it feels like a hot sensation, a hot flash is essentially your body's air conditioning turning on at the wrong time.

These changes in your brain that cause hot flashes are related to the rate of the loss of estrogen rather than the levels of estrogen. So what matters is the speed of the estrogen decline rather than how much estrogen you have.

Because after several years of menopause, when your estrogen is at the lowest, hot flash symptoms usually disappear.

It is during perimenopause - the period leading into menopause when periods start becoming irregular - and at the start of menopause, when you still have higher levels of estrogen in your body that hot flash symptoms begin and are at their worst.

That is why doctors say VMS - vasomotor symptoms - a technical term for hot flashes - are said to occur during the menopause transition. Up to 80% of women experience hot flashes during the menopause transition (Avis et al. 2015).

So it’s the change in the hormone levels that causes hot flashes and not the low levels of estrogen.

How long do hot flashes last?

Estimates for how long women experience hot flashes vary depending on the study.

One recent study that was part of the study of women’s health across the nation, or SWAN study, published in the Journal of the American Medical Association in 2015, found that the median total duration of hot flashes was 7.4 years.

However, there were nuances to this as women who started getting hot flashes in the perimenopausal period had hot flashes for a median of 11.8 years, 9.4 years of which was post-menopausal.

In contrast, women who first got hot flashes after menopause had symptoms for a median of 3.4 years (Avis et al. 2015).

Basically - the sooner you start experiencing hot flashes the longer they will last.

In addition to genetics and race which seem to be big factors, lifestyle factors have also been associated with more vasomotor symptoms. Hence, if you have mild symptoms, doctors will usually advise simple lifestyle changes.

How to treat hot flashes

Behavioral Modifications and Lifestyle Changes

The American College of Obstetricians and Gynecologists recommend some of the following changes:

1. Dress in layers so you can take them off and on easily depending on how you feel. And carry cold water around.
2. Avoid alcohol and coffee which can trigger hot flashes.
3. Quit smoking if you smoke.

Research has also demonstrated that anxiety can exacerbate hot flashes.

For instance, a study that compared women who had normal levels of anxiety to those with moderate anxiety found that those with moderate anxiety were three times more likely to report hot flashes. Similarly, those with high levels of anxiety were nearly five times more likely to report experiencing hot flashes.(Freeman et al. 2005).

Breathing exercises can help in a huge way. Several studies have found that slow and deep paced breathing can help reduce hot flash frequency in postmenopausal women by about 50% compared to placebo control procedures. Hence, paced breathing training can produce significant declines in hot flash frequency (Freedman 2014).

Hormone Replacement Therapy

For those with moderate to severe hot flashes, lifestyle changes may not be enough. In this case, hormone replacement therapy or HRT with estrogen alone or with combination of both estrogen and progestin, which is a lab made version of progesterone, is recommended as the first line therapy.

HRT, because it replaces the estrogen that is lost, can benefit not only hot flashes but other symptoms of menopause, and this includes bone density loss and post-menopausal skin changes like accelerated wrinkling.

The bad news is that HRT is not recommended for some women - because it increases the risk of breast cancer and stroke. So, HRT is generally not recommended as a long-term treatment and is often tapered off after 1 to 2 years.

And when you stop taking hormone replacement therapy (HRT), the hot flashes may return.

If you experience hot flashes after weaning off HRT or if you were advised against HRT due to a risk factor such as a history of breast cancer, then your doctor may recommend alternative non-hormonal medications like SSRIs, SNRIs, gabapentin, or clonidine to manage your symptoms.(Nelson 2006, Bansal 2019).

These drugs are best known for treating depression and anxiety. Let’s get into why antidepressants work for hot flashes.

Click here for our newsletter on HRT

Non-hormonal Drug Treatment: SSRIs and SNRIs, Gabapentin, Clonidine

Estrogen helps increase the production of serotonin and endorphins.

Though not fully understood, it is believed that when the level of estrogen in the body drops in the menopause transition, it can cause a decrease in serotonin and endorphin levels. This drop can trigger an increase in norepinephrine levels, which can disrupt the hypothalamic thermostat, causing hot flashes.

Norepinephrine is a hormone and neurotransmitter, which is primarily involved in the body's stress response - including blood pressure, heart rate, and breathing rate. What’s less well known is that Norepinephrine is also used in body temperature regulation.

When the body detects a change in temperature, norepinephrine is released in response to signals from temperature-sensitive neurons in the hypothalamus.

The hypothalamic thermostat is a part of the hypothalamus that regulates body temperature. It maintains a balance between heat production and heat loss to keep the body at a stable temperature, which is known as the thermoneutral zone.

When the body temperature rises above or falls below the thermoneutral zone, the hypothalamic thermostat triggers responses such as sweating or shivering to restore the body to its normal temperature.

And norepinephrine is effectively a dial that turns up or down this hypothalamic thermostat.

When there is too much norepinephrine in the hypothalamus controlling the body's thermostat, the thermostat gets stuck on 'hot.' This means that even when the temperature is comfortable, a slight increase in temperature can trigger the thermostat to turn on the air conditioning at full blast.

In other words, the hypothalamus becomes overly sensitive to changes in body temperature, leading to hot flashes.

So, hot flashes are really driven by your brain’s condition.

Hormones and neurotransmitters are both chemical messengers in the body. Hormones are made by endocrine organs and sent through the bloodstream, while neurotransmitters are made by brain cells - the neurons. There are other differences as well but it’s not important to know them at this point.

Circling back to hot flashes, the hypothalamic thermostat is what goes haywire causing hot flashes. And hormones and neurotransmitters drive the thermostat.

So, after hormone replacement therapy, drugs that affect serotonin or norepinephrine levels are the next most effective treatment for hot flashes (Nelson et al. 2006, Freedman 2014, Bansal 2019).

SSRIs - Paroxetine (Brisdelle)

SSRI stands for Selective serotonin reuptake inhibitors. These are commonly sold as antidepressant drugs.

You might have heard of the drug Paxil, which is commonly used to treat depression. The underlying active ingredient of Paxil is paroxetine, which is an SSRI. This same paroxetine is FDA approved for treating hot flashes and sold under the trade name Brisdelle.

Many drugs that share the same underlying active compound will have different trade names depending on the company that makes it and what condition it becomes approved for by the FDA.

Other SSRIs have also shown effectiveness in treating hot flashes in clinical trials but have not yet been FDA approved.

When the FDA hasn’t approved its use for hot flashes, a doctor may prescribe it anyway off-label for hot flashes if there are trials showing its benefits (Nelson et al. 2006, Freedman 2014, Bansal et al. 2019)

SNRIs - Effexor (venlafaxine)

Now, there are also SNRIs, which stands for selective norepinephrine reuptake inhibitors.

However, SNRIs generally affect both norepinephrine and serotonin levels.

Antidepressant Effexor is based on the active ingredient venlafaxine, which is an SNRI. Effexor has been found to be effective in treating hot flashes, but again, it would be prescribed off-label at doctor’s discretion.

When would a doctor use an SNRI over SSRI to treat hot flashes?

SSRIs like paroxetine can interact with drugs like Tamoxifen which are used to treat breast cancer, so, venlafaxine may be prescribed in patients undergoing cancer treatment (Nelson et al. 2006, Freedman 2014, Bansal et al. 2019).

Anticonvulsant and Antihypertensive - Gabapentin and Clonidine

For those with predominantly night time hot flashes and night sweats, doctors may prescribe a different drug called gabapentin, to help manage these symptoms.

Gabapentin is what is called an anticonvulsant because it helps treat seizures in epileptics. Its trade name is Neurontin.
It acts on the GABA system, with GABA being the main inhibitory neurotransmitter in your brain. GABA levels can modulate norepinephrine levels.

The reason gabapentin may be preferable for night time hot flashes and night sweats is that gabapentin has the added benefit that it can also help people maintain their sleep cycle better. It also has anti-anxiety effects.

Gabapentin may also be prescribed in women who are on Tamoxifen for breast cancer treatment (Bansal et al. 2019, Nelson et al. 2006).

Finally, Clonidine which is an antihypertensive used to treat high blood pressure, and it can also be used to treat hot flashes. This drug has also been shown to work in breast cancer survivors who were on Tamoxifen. It also works by lowering norepinephrine levels (Freedman 2014).

Summary

In summary, hot flashes are experienced as skin warmth, flushing, and sweats followed by chills, but their root cause is a change in neurotransmitter levels in response to falling estrogen levels.
This is similar to how changes in neurotransmitters can cause mood swings during PMS.

However, during perimenopause and menopause, the continuous decline in estrogen affects the hypothalamic system that regulates core body temperature, causing it to become overly sensitive and stuck on 'hot' regardless of the actual temperature.

Hot flashes are more common during the transition into menopause such as in perimenopause or the first few years of menopause and eventually disappear for most women - albeit it could take years and years.

If mild, simple lifestyle changes are effective. If more moderate and severe, hormonal or nonhormonal drug therapies are options.

That's it!  Thanks for reading.  Don't forget to check out our other newsletters.

-Team Maelove

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.

References

Avis NE, Crawford SL, Greendale G, Bromberger JT, Everson-Rose SA, Gold EB, Hess R, Joffe H, Kravitz HM, Tepper PG, Thurston RC (2015). “Duration of Menopausal Vasomotor Symptoms Over the Menopause Transition.” JAMA Intern Med. 175(4): 531-539.

Bansal R, Aggarwal N (2019). “Menopausal Hot Flashes: A Concise Review.” J Mid-Life Health. 10: 6-13.

Freedman RR (2014). “Menopausal Hot Flashes: Mechanisms, Endocrinology, Treatment.” J Steroid Biochem Mol Biol. 142: 115-120.

Freeman E, Sammel MD, Lin H, Gracia C, Kapoor S, Ferdousi T (2005). “The role of anxiety and hormonal changes in menopausal hot flashes.” Menopause 12(3): 258-266.

Nelson HD, Vesco KK, Haney E, Fu R, Nedrow A, Miller J, Nicolaidis C, Walker M, Humphrey L (2006). “Nonhormonal Therapies for Menopausal Hot Flashes.” JAMA 295(17): 2057-2071.