Hot Flashes

What is Hot Flashes?

Hot flashes are sudden, spontaneous, short episodes of warmth, usually felt on the chest, neck and face, followed by sweating. They are the most common reason women seek care during the perimenopausal period.^[1]

Common symptoms

During an episode you may feel heat and flushing, then sweating. Some people also have a racing heart, headache, weakness, anxiety, or a chill afterward.^[1] Most episodes last less than 5 minutes, and the number varies from several a week to about 10 a day.^[1]

Hot flashes at night are called night sweats and can disturb sleep. Warm rooms, hot drinks and emotional stress can trigger an episode.^[1]

Causes and risk factors

Hot flashes are most often caused by the hormonal changes of the menopause transition. The exact cause is not known, but the leading idea is that a falling or changing estrogen level affects the temperature-control center in the hypothalamus.^[2]

Risk factors include smoking, higher body weight early in the transition, anxiety, depression, hysterectomy or removal of the ovaries, and breast cancer treatments.^[3] They can also follow medicines that lower hormone levels. Hot flashes often last for years, and they tend to last longer when they begin early in the transition.^[3]

How it is diagnosed and treated conventionally

Hot flashes are usually recognized from your symptoms and age. A provider may check for other causes if symptoms are unusual, such as thyroid disease, medicines or an earlier-than-expected menopause.^[1]

Hormone therapy remains the most effective treatment and is generally considered for women within 10 years of their final period. For women who cannot or prefer not to use it, evidence-supported nonhormonal options include cognitive behavioral therapy, clinical hypnosis, certain antidepressants, gabapentin and fezolinetant.^[4]

Why Hot Flashes calls for a whole-person approach

Hot flashes reflect more than one system. Hormones, the brain's temperature control, stress, sleep and general health all play a part, and they differ from woman to woman.^{[2, 3]}

Care that looks at several of these factors can be a reasonable addition to medical treatment, particularly for women who cannot take hormones.

Hormone changes

The rate of change in estrogen, more than the absolute level, appears to influence temperature control in the hypothalamus.^[2] This fits with the relief many women get from hormone therapy.

Narrowed comfort zone for temperature

One proposed explanation is that the range of body temperatures the brain tolerates without sweating or shivering becomes narrower. Small rises then trigger a heat-loss response.^[5]

Stress, mood and sleep

Anxiety and depression are associated with more hot flashes, and heat or emotional stress can set off an episode.^{[1, 3]} Night sweats and poor sleep feed each other.

Medical treatments and conditions

Breast cancer treatments, surgery that removes the ovaries and some medicines can cause hot flashes.^[3] In these groups, the choice of treatment needs your oncology or gynecology team.

Acupuncture for Hot Flashes

What the research shows

The research is mixed and the evidence is limited. Acupuncture often looks helpful when compared with no treatment, but the effect mostly disappears when compared with sham acupuncture.

A Cochrane review of 16 trials with 1,155 women found no significant difference in hot flash frequency between acupuncture and sham acupuncture, and a small difference in severity in very low-quality evidence. Acupuncture reduced flashes more than no treatment, but those trials had no sham comparison, and acupuncture was less effective than hormone therapy. The authors judged the overall evidence insufficient.^[6] An umbrella review found acupuncture beat no acupuncture for symptoms and quality of life, but with smaller or non-significant differences versus sham, so some of the benefit may be due to non-specific effects.^[7]

Two well-run trials reflect this. In an Australian trial of 327 women with moderately severe hot flashes, a standardized Chinese medicine acupuncture course was not better than a non-penetrating sham.^[8] A Chinese trial of 360 women found that electroacupuncture gave only a small advantage over sham for overall menopausal symptoms and hot flash scores, below the level considered clinically important, though quality of life scores improved more.^[9]

For women treated for breast cancer, the evidence is thinner. One trial in 120 survivors found electroacupuncture produced the largest reduction in hot flash scores, ahead of sham acupuncture, gabapentin and placebo pills, but the authors called the findings preliminary.^[10]

The North American Menopause Society's 2023 position statement did not recommend acupuncture for hot flashes, citing limited or inconsistent evidence.^[4]

How acupuncture may work

One hypothesis is that acupuncture could act on the narrowed temperature comfort zone by raising estrogen, endorphin or serotonin levels or lowering noradrenaline. A review of the trials concluded that results support needling relieving flashes in general, but not a point-specific effect.^[5] Placebo effects are strong in hot flash trials, and these mechanisms are unproven.

What treatment involves

Treatment uses fine, sterile, single-use needles at points on the body, usually left in place for about 20 to 40 minutes. The large trials gave about 10 treatments over 8 weeks, or more in the Chinese trial.^{[8, 9]} We reassess after a short course of visits.

In prospective studies, about 9 in 100 patients had a minor reaction such as bleeding, soreness or a flare at the needle site, and serious events occurred in about 1 in 10,000 patients.^[11] Tell the practitioner first if you have a bleeding disorder, take blood thinners, are pregnant, or have a pacemaker (relevant to electroacupuncture).

Ayurvedic medicine for Hot Flashes

The Ayurvedic view

In Ayurveda, the years around menopause are described as a time when Vata rises, and the heat and sweating of hot flashes are attributed to aggravated Pitta, the principle linked to heat. These are traditional categories used to choose care, not biomedical diagnoses.

Therapies that may be used

Care is individualized and traditionally combines:

• Cooling diet and routines, regular meals and enough sleep
• Herbs such as shatavari (Asparagus racemosus) and ashwagandha (Withania somnifera), prescribed individually^{[12, 13]}
• Stress-reducing practices such as gentle yoga and breathing exercises
• Oil massage for relaxation

Panchakarma is not appropriate during pregnancy, acute illness or frailty, and its use needs care in women with cancer or other serious illness.

What the research shows

The research is very limited and was done on menopausal symptoms in general, not on hot flashes alone. In a placebo-controlled trial of 100 perimenopausal women, an ashwagandha root extract was followed by lower overall menopause symptom scores and better quality of life than placebo over 8 weeks, with changes in some hormone levels.^[13]

In a trial of 135 women, shatavari root extract combined with ashwagandha improved overall symptom scores compared with placebo and with shatavari alone. Hot flashes were a secondary outcome and the abstract does not report their result.^[12] These trials were small and short, and no systematic review of Ayurveda for hot flashes was found.

Herbal medicine for Hot Flashes

Herbs and formulas that have been studied

Herbs studied for hot flashes include Chinese herbal formulas, black cohosh, and plant estrogens (phytoestrogens) such as soy isoflavones.^{[14, 15, 16]} The most often prescribed herb in Chinese formula trials was bai shao (white peony).^[17]

What the research shows

The evidence is limited and inconsistent. A Cochrane review of 22 trials of Chinese herbal medicine found insufficient evidence that it was better or worse than placebo or hormone therapy for hot flashes, and noted that the evidence was very low to moderate in quality.^[14] A later meta-analysis of 19 trials found that Chinese herbal formulas reduced hot flash severity compared with placebo and performed similarly to hormone therapy on some measures.^[17]

A meta-analysis of 22 trials found that black cohosh extracts were linked to fewer hot flashes than placebo, with a modest effect.^[15] A JAMA review of 62 trials found that phytoestrogens modestly reduced hot flash frequency and several herbal remedies, but not Chinese herbs, helped overall. It described most trials as having a high risk of bias.^[16]

The North American Menopause Society did not recommend supplements or herbal remedies for hot flashes in 2023.^[4]

Safety and herb-drug interactions

Herbs are active substances and are chosen individually by a qualified practitioner. Black cohosh products have been linked to clinically apparent liver injury, some severe.^[18] Report any dark urine, yellow skin or eyes, or upper abdominal pain right away.

Herbs can interact with medicines. For example, St John's wort has been reported to cause serotonin syndrome with SSRI antidepressants, which are sometimes prescribed for hot flashes.^[19] Tell us about all medicines and supplements, including tamoxifen, aromatase inhibitors, blood thinners and thyroid medicine. Herbs with estrogen-like activity need an oncologist's approval for anyone with a history of hormone-sensitive cancer.

In one study, about one fifth of Ayurvedic products bought online contained detectable lead, mercury or arsenic, so herbs should come from tested sources.^[20] Tell us if you are pregnant, breastfeeding, or have liver or kidney disease.

Transdermal medication therapy, an herbal preparation applied to the skin, is also offered. We found no studies of it for hot flashes.

Translating traditional medicine into modern biological language

The comparisons here are interpretation, not equivalence. Chinese medicine often describes hot flashes as kidney yin deficiency with heat. The Australian acupuncture trial used that diagnosis to select its participants.^[8] Ayurveda describes aggravated Pitta during a Vata stage of life.

Researchers studying the same symptom look at estrogen change and a narrowed temperature comfort zone in the hypothalamus, along with endorphin, serotonin and noradrenaline signaling.^{[2, 5]} These ideas overlap loosely with the traditional pictures, but no study has shown that a pattern or dosha corresponds to a specific biological process.

How this care fits with your medical care

Complementary care for hot flashes works alongside your physician. Keep your gynecologist, primary care physician or oncology team, and do not start, stop or change hormone therapy, antidepressants or other prescribed medicines without your prescriber. We do not diagnose the cause of hot flashes, so new or unusual symptoms should be medically evaluated.

Please bring your diagnosis, a full list of medicines and supplements, any cancer treatment history, and recent test results.

When to seek urgent medical care

Hot flashes are usually harmless, but some symptoms need medical attention.

• Chest pain, pressure, or shortness of breath with a racing or irregular heartbeat
• Fainting or severe dizziness
• Vaginal bleeding after menopause, or very heavy or irregular bleeding
• Drenching night sweats with fever, unexplained weight loss or swollen glands
• Hot flashes starting before age 40, which need evaluation for early ovarian failure
• Thoughts of harming yourself; call or text 988, the Suicide and Crisis Lifeline

For emergencies, call 911 or go to the nearest emergency department.