Hot flashes are an annoying and exhausting part of perimenopause and menopause for many women. Perimenopause is the time when hormone levels decline and menstrual cycles become erratic. Menopause begins when a woman has not had a period for one year. Over 75 percent of women in North America experience hot flashes during some part of the transition into menopause. The entire experience varies greatly among women. Hot flashes, episodes of intense heat sensation, sweating and flushing, can be accompanied by palpitations and anxiety and can last a few seconds or several minutes. Some women experience them hourly while others have them only occasionally. The majority of symptomatic women have hot flashes for 1 to 2 years but over 15 percent may have persistent hot flashes for up to 30 years. (1) The transition into menopause is a unique experience for each woman and can be supported by different treatment options, individually designed for the needs of each woman.
It is interesting to look at what is known about hot flashes from a biomedical perspective. Robert R. Freedman, Ph.D. (Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan) has conducted research into hot flashes and found a very interesting piece of the puzzle. He found that when estrogen levels are compared in menopausal women with and without hot flashes, no correlation is found between the level of estrogen (plasma, urinary and vaginal levels were compared) and the occurrence of hot flashes. (3) In other words, menopausal women with hot flashes do not have lower levels of estrogen than menopausal women without hot flashes. However, it is definitely known that hormone replacement therapy using estrogen, sometimes combined with other hormones such as progesterone, is the surest way to alleviate hot flashes. Certainly, there is more to the story than just hormone levels.
Core body temperature is regulated by the hypothalamus in our brains. Our bodies are able to keep our core body temperature in a narrow range even though we experience a wide range of temperatures externally. Hot flashes are a heat dissipation response in the body. When you get too hot, small blood vessels in the periphery of your body dilate (vasodilation) bringing heat to the surface of the skin which allows the heat to escape. We also sweat, which carries heat out of the body in the sweat and cools the body by evaporation. There is a thermoneutral zone where our bodies are comfortable. When we get hot, the upper threshold of the thermoneutral zone is reached and we sweat and experience vasodilation in order to cool down. When we get cold and the lower threshold is reached we shiver in order to warm up. When our bodies' core temperature is in the thermoneutral zone we do not shiver or sweat.
Robert R. Freedman's research found that the thermoneutral zone in postmenopausal women with hot flashes is narrowed. Not only is the upper threshold for sweating lowered but the lower threshold for shivering is elevated, creating a narrowed thermoneutral zone where the body is comfortable. This helps explain why menopausal women also experience chills. Freedman also found that elevated levels of norepinephrine in the brain are likely the cause of the narrowed thermoneutral zone. (3) Norepinephrine is a neurotransmitter that is produced in the brain, nervous system and adrenal glands. The general function of norepinephrine is to mobilize the brain and body for action. It is considered a part of the fight or flight response of the sympathetic nervous system but is also important for alertness, formation and retrieval of memory and focused attention.
Another neurotransmitter, serotonin, acts in opposition with norepinephrine and balances the effects of norepinephrine. Serotonin is primarily found in the gastrointestinal tract, blood platelets and central nervous system and is derived from the amino acid tryptophan. It helps to regulate gastrointestinal motility, appetite, mood and sleep. When serotonin levels are low, norepinephrine levels are able to rise. The presence of estrogen increases the number of serotonin receptors in the brain, increasing serotonin production and inhibiting serotonin re-uptake allowing more serotonin to be used. So, when estrogen levels fall during menopause there is less serotonin function and a potential for increased norepinephrine activity. (4) Antidepressant drugs are sometimes prescribed for hot flashes and can be helpful. They are serotonin re-uptake inhibitors (SSRI's) and while they do not increase the amount of serotonin in the body they limit the reabsorption of serotonin making it more available to bind to its receptor. However, SSRI's come with side effects that are unacceptable to many women.
In Chinese medical theory, menopausal hot flashes are considered to be an imbalance in the yin and yang of the body. Yin is the substance of the body such as the tissues, fluids and blood. Yang is the energy of the body and the functioning of all the organ systems. Yin is cool and moist while yang is warm and dry. As practitioners of Chinese medicine, we attempt to balance these two forces to maintain the health of our patients. As women age and hormonal levels drop, this usually is diagnosed as a decrease of yin. This leaves a relative excess of yang. It's not that there is too much yang, but the amount of yin has decreased relative to the amount of yang. So, at times, this relative excess of yang exhibits itself as a burst of heat, usually felt as a wave of energy and heat in the body. The chills that postmenopausal women can also experience are diagnosed as a yang deficiency. Simultaneous yin and yang deficiencies can exist, with women experiencing waves of heat and then waves of chills which correlates with the narrowed thermoneutral zone that Freedman studied. There can be other Chinese medical diagnoses for hot flashes but usually there is some degree of yin deficiency.
Thankfully, there are many treatment options for hot flashes. Lifestyle modifications are extremely important including a good diet full of vegetables and healthy protein as well as limiting sugar, caffeine and alcohol. Smoking cigarettes is not a good idea. Regular exercise and reducing stress is also important. And staying well-hydrated is crucial. However, sometimes a good lifestyle is not enough.
Auricular (ear) acupuncture offers a unique treatment option. The ear (the outer part, not the ear canal) is a microsystem of the entire body, meaning that the ear has representative areas for all body parts, including the brain. In fact, auricular acupuncture is very effective at calming the nervous system and switching people out of the fight or flight (sympathetic) aspect of the autonomic nervous system and into the rest and digest (parasympathetic) aspect. It can be used in many instances where a calming effect is desired including insomnia, anxiety, stress, inflammation, pain disorders and hot flashes. There is an acupuncture point in the ear that corresponds to the hypothalamus, which we now know is very confused in women with hot flashes. Other supporting auricular points are used in combination with the hypothalamus point to create a more relaxed nervous system. Using auricular points in combination with body acupuncture points creates balance in the body's nervous system and deep relaxation. Studies have shown that acupuncture is beneficial to reduce the number of hot flashes and I have certainly seen this to be true. (6)
Chinese herbal medicine is very effective at relieving hot flashes. The treatment is based on calming the rising yang and nourishing the depleted yin and yang. Yes, yang energy can be both deficient and rising in the body when it is not balanced. It is more difficult to increase yin and yang in the body with acupuncture and this is where herbal medicine has the advantage. There are wonderful Chinese herbal formulas that cool the unbalanced yang and nourish the depleted yin to achieve greater balance in the body. Chinese herbal medicine can help with almost all the discomforts of menopause. The beauty of Chinese herbal medicine is that it is a very individualized approach, taking the person's entire mental, physical and emotional picture into consideration and creating a synergistic blend of herbs specifically for that person at that time. The herbal formulas have been used and documented for thousands of years and the herbs that I use are routinely tested and found to be free of pesticides or other contaminates. The formula Zhi Bai Di Huang is often a good place to start. It has yin nourishing herbs along with herbs that cool yin-deficient heat. Some of the herbs in the formula have an astringent function which helps with sweating. It is a beautifully well-balanced formula and is appropriate in many cases.
There are also phytoestrogen therapies that can help to relieve hot flashes. Phytoestrogens are plant-based substances that are structurally similar to estrogen and bind to estrogen receptors in the body. The main phytoestrogen groups are flavonoids, lignans, coumestans and stilbenes and are present in foods such as soybeans, grains, fruits and vegetables. Many studies have focused on isoflavones, which are a subgroup of the flavonoids, and are present in soybeans. Isoflavones have been studied extensively because Asian women, who traditionally consume a soy-rich diet, have a lower risk of breast cancer, heart disease and experience less hot flashes than American women. Up to 80% of North American and European women experience hot flashes while only 20% of Asian women have problems with hot flashes. It is thought that the higher consumption of soy in Asian diets is responsible for the difference. Studies also show that women who consume soy in their diets as children and adolescents have fewer problems with hot flashes later in life than women who only start to consume soy foods as adults. (7) While there is some evidence that phytoestrogens are protective, there is no clear consensus when breast cancer is a concern.
Recently, S-equol, a metabolite of the soy isoflavone daidzein, has received attention for its ability to alleviate hot flashes and muscle pain in menopausal women. S-equol is created when intestinal bacteria metabolize daidzein. About 50% of Asians and only 25% of non-Asians host the intestinal bacteria that convert daidzein into S-equol. This fact may help explain why in past research studies the use of phytoestrogens, especially soy, has had variable results in alleviating hot flashes. Clinical trials that evaluated a product that contains 5 mg of S-equol (Equelle) found that hot flashes were reduced when the product was taken twice a day for 8 weeks with the best results achieved after 12 weeks. The trials were limited in scope but in both Japanese women and women in the United States, hot flashes were significantly reduced. (5)
The neurotransmitter connection to hot flashes is very interesting. 5-Hydroxytryptophan (5-HTP) is a precursor in the biosynthesis of the neurotransmitter serotonin and is widely available as a supplement. It helps to increase serotonin production and is used for sleep disorders, depression, anxiety, appetite control, headaches and other disorders in which serotonin levels are believed to be a factor including temperature control. It is important to note that 5-HTP can interact with pharmaceutical drugs, especially serotonin re-uptake inhibitors (SSRI's, common antidepressant drugs) so it is best to consult with your health care practitioner before taking 5-HTP. It is possible that increasing serotonin levels can help counter the effect of increased levels of norepinephrine. However, the interaction of neurotransmitters is more complex than simply the dynamics between norepinephrine and serotonin. There are other excitatory neurotransmitters besides norepinephrine and other inhibitory neurotransmitters besides serotonin creating an intricate, delicately balanced system. There are tests that measure the neurotransmitters and supplements to help balance them.
Finally, a word on hormone replacement therapy. The entire subject is beyond the scope of this article, but I want to include it as a treatment option. In 2002, one segment of The National Institute of Health's Women's Health Initiative Study was ended early because of the finding of increased risk of breast cancer and cardiovascular disease in women on the combination of estrogen and progestin (conjugated equine estrogens, 0.625 mg/d, plus medroxyprogesterone acetate, 2.5mg/d). As news of this result spread, it resulted in a 71 percent reduction in the use of hormone replacement therapy as a treatment for menopausal complaints according to the North American Menopause Society. Since then there has been an increase in the number of women using compounded bioidentical hormone therapy. This therapy consists of tests (blood, saliva, urine) to determine current hormonal levels and personalized prescriptions for hormone combinations based on the results of the tests. The hormones used are identical, on a molecular level, to the hormones produced in the body. The proponents of this method suggest it is safer than conventional hormone replacement therapy because the supplemental hormones used are identical to what the body produces and more effective because they also consider other hormones, such as testosterone, that are not looked at in conventional treatments. It is controversial in conventional medicine because there is distrust of the testing and the consistency of the level of hormones in the prescribed treatments. It is argued that bioidentical hormone therapy has not been studied enough to know whether it is safer than conventional hormone replacement therapy. (7) I encourage women to do some of their own research and discuss options with their healthcare practitioners if they are interested in hormone replacement therapy.
Hot flashes can be stubborn and uncomfortable. For many women they are short-lived and for those who need help there are excellent treatment options to help make them manageable or non-existent. The transition into the menopausal years can be bumpy and as awkward as puberty. But you don't have to go it alone. There are helpful treatments to smooth out the ride. It's also important to focus on the positive. Not having a period and the hormonal fluctuations that accompany the monthly cycle can be wonderfully freeing! And the wisdom that comes with aging is . . . priceless.
When I am an old woman, I shall wear purple.
1. Phuong Khanh H. Morrow, Danielle N. Mattair, Gabriel N. Hortobagyi, Hot Flashes: A Review of Pathophysiology and Treatment Modalities. Oncologist. November 2011.
2. DW Sturdee, The Menopausal Hot Flush - Anything New? Maturitas. May 2008.
3. Robert R. Freedman, Ph.D. Menopausal Hot Flashes: Mechanisms, Endocrinology, Treatment. Journal of Steroid Biochemistry and Molecular Biology. July 2014.
4. Leszek A. Rybaczyk, Meridith J. Bashaw, Dorothy R. Pathak, Scott M. Moody, Roger M. gilders, Donald L. Holzschu, An Overlooked Connection: Serotonergic Mediation of Estrogen-Related Physiology and Pathology. BMC Womens Health. December 2005.
5. WH Utian, M. Jones, KD Setchell, S-Equol: A Potential Nonhormonal Agent For Menopause-Related Symptom Relief. Journal of Womens Health, March 2015.
6. E. Borud, A. White, A Review of Acupuncture for Menopausal Problems. Maturitas. June 2010.
7. Mayo Clinic Proceedings, v.86(7); July, 2011