Hot Flashes: Causes and How to Stop Them

What a hot flash feels like

A flash typically starts with a sudden feeling of heat in the chest or face that spreads upward. The skin may redden and break into a sweat. The heart may race and some people feel anxious or have a sense of pressure in the head. As it fades, sweat evaporates and you may feel chilled. Flashes at night are called night sweats and can soak bedding and break sleep.

Frequency ranges from a few a week to many an hour.

Why menopause causes hot flashes

The brain's thermostat, in the hypothalamus, keeps body temperature within a narrow comfort zone. Falling estrogen narrows that zone, partly through increased activity of brain cells that use a signal called neurokinin B. Small rises in core temperature then trigger an exaggerated cooling response: blood vessels in the skin open, and sweating starts.

Flashes typically begin in perimenopause, when periods become irregular, peak around the final period, and gradually fade. For some women they last 10 years or more. They tend to be more frequent and last longer in Black women and in women whose flashes start early.

Removal of both ovaries causes abrupt surgical menopause and often severe flashes.

Other causes of hot flashes

Hot flashes not caused by menopause

• Medicines: tamoxifen and aromatase inhibitors for breast cancer, opioids, some antidepressants, niacin, calcium channel blockers, nitroglycerin and steroids.
• Overactive thyroid: heat intolerance, sweating, weight loss, tremor and palpitations.
• Anxiety and panic attacks.
• Alcohol, especially in people with an inherited sensitivity, and spicy food.
• Pregnancy and the postpartum period.
• Infections such as tuberculosis, and lymphoma, which cause night sweats with fever and weight loss.
• Rare tumors: carcinoid syndrome causes flushing with diarrhea and wheezing. Pheochromocytoma causes episodes of headache, sweating, pounding heart and high blood pressure.

Hot flashes in men

Men get hot flashes most often during hormone therapy for prostate cancer, which lowers testosterone sharply. Low testosterone from other causes, overactive thyroid, medicines and anxiety are other reasons. A man with new hot flashes and no clear cause should be checked.

Common triggers

• hot drinks, caffeine and alcohol
• spicy food
• warm rooms, heavy bedding and layered clothing
• stress
• smoking

How hot flashes are evaluated

For a woman in her mid-40s or older with irregular periods, the diagnosis is usually clinical. Blood tests for hormones are not needed to confirm menopause over 45. Tests are useful in younger women (FSH to check for early menopause), and when the picture is unusual: thyroid function, blood count, and tests for rarer causes if there is diarrhea, wheezing or very high blood pressure.

How to stop hot flashes

Self-help

• Dress in layers, keep the bedroom cool, use a fan and breathable bedding.
• Sip cold water at the start of a flash.
• Limit alcohol, caffeine and spicy food if they trigger you.
• Stop smoking, and lose excess weight, which is linked to more flashes.
• Cognitive behavioral therapy and clinical hypnosis have good evidence for reducing how much flashes bother you.
• Paced breathing (slow, deep breaths when a flash begins) helps some people.

Hormone therapy

Menopausal hormone therapy (estrogen, plus a progestogen if you have a uterus) is the most effective treatment, reducing flash frequency by about three quarters. For most healthy women under 60 or within 10 years of menopause, benefits usually outweigh risks. It is not suitable after some cancers, blood clots or strokes. Discuss your personal risks with a doctor.

Non-hormonal medicines

• Fezolinetant: a newer tablet that blocks the neurokinin signal in the brain's thermostat.
• Low-dose SSRIs or SNRIs such as paroxetine or venlafaxine.
• Gabapentin, useful for night sweats.
• Oxybutynin and clonidine in some cases.

Note that some antidepressants interact with tamoxifen, so women with breast cancer need careful prescribing.

Supplements

Black cohosh, soy isoflavones and evening primrose oil have weak or inconsistent evidence, and supplement quality varies. Check with a doctor or pharmacist before using them, especially after breast cancer or with liver disease.

Frequently asked questions

What causes hot flashes besides menopause?

Common non-menopausal causes are medicines (tamoxifen, opioids, some antidepressants), overactive thyroid, anxiety, alcohol, spicy food and pregnancy. Rarely, infections, lymphoma or hormone-producing tumors cause flushing. Unexplained hot flashes with weight loss, fever or diarrhea should be checked.

How long do menopausal hot flashes last?

Each flash lasts 1 to 5 minutes. Over a lifetime, hot flashes continue for a median of about 7 years, and around 1 in 10 women have them for more than a decade. They usually become less frequent and milder over time.

Do men get hot flashes?

Yes. Men most often get them during hormone treatment for prostate cancer, because testosterone falls sharply. Low testosterone, overactive thyroid, medicines and anxiety can also cause them. New unexplained hot flashes in a man should be assessed by a doctor.

What is the fastest way to stop a hot flash?

You cannot stop one instantly, but you can shorten the discomfort: move to a cooler place, use a fan, sip cold water, remove a layer and breathe slowly and deeply. For frequent flashes, hormone therapy and non-hormonal medicines reduce how often they happen.

Are hot flashes a sign of something serious?

Usually not. In women around menopause they are a normal part of the hormonal transition. They need checking if they start before 40, occur in men, or come with fever, weight loss, diarrhea, wheezing or very high blood pressure.