What Causes Hot Flashes, and How Long Do They Last?

You’re mid-sentence in the 2 p.m. meeting when the heat starts under your collarbone and climbs. By the time it reaches your face you can feel the color. Everyone else is wearing a cardigan.

What a hot flash is

The Menopause Society¹ describes a sudden, intense wave of heat that mostly hits the face, neck and chest. It usually lasts 1 to 5 minutes and can come with sweating, chills, a racing heart and a jolt of anxiety. Up to 80% of women get them during menopause.

At night, the National Institute on Aging (NIA)² says, the same thing is called a night sweat.

The cause is the shift in hormones. NIA² explains that during the menopause transition the ovaries work less effectively, estrogen and progesterone decline, and it’s believed that this change causes hot flashes. Cleveland Clinic³ ties them to falling estrogen too.

How long they last

The honest answer is years.

The NHS⁴ says menopause symptoms usually last 7 to 9 years, sometimes longer, and can change over that time. The Menopause Society’s¹ average of 7 to 10 years sits right alongside it.

The best long-term data comes from the Study of Women’s Health Across the Nation. A 2015 study in JAMA Internal Medicine⁵ followed 1,449 women with frequent hot flashes and night sweats and found a median total of 7.4 years.

The median hides a wide range. Women whose symptoms began before menopause or in early perimenopause had a median of more than 11.8 years. Women whose symptoms started after menopause had a median of 3.4 years. By race and ethnicity the medians ran from 4.8 years in Japanese women to 10.1 years in African American women, and NIA² notes that African American and Hispanic women have hot flashes for more years than white and Asian women.

So the question “how long?” has no single answer, and when yours began matters.

Why some women get hit harder

The Menopause Society¹ lists higher abdominal fat, especially in younger women, current or past smoking, and surgical menopause, where the ovaries are removed. Surgical menopause produces more frequent and more severe symptoms than natural menopause. NIA² adds that women who are overweight or obese may have more frequent and severe hot flashes.

What helps at home

NIA² says to start with lifestyle changes before medication. For nights, lower the bedroom temperature, drink a small amount of cold water before bed, layer the bedding so you can adjust it, and run a fan. Cleveland Clinic³ adds lightweight sleepwear in breathable fabrics like cotton or linen.

During the day, NIA² suggests layers you can remove at the start of a flash, a portable fan, and avoiding alcohol, spicy foods and caffeine, which can make symptoms worse.

Here’s the catch. The Menopause Society¹ says the evidence is limited for cooling techniques and trigger avoidance, and also for acupuncture and supplements. The measures it calls evidence-supported are weight loss, cognitive behavioral therapy and clinical hypnosis. NIA² mentions early-stage research suggesting hypnotherapy and mindfulness meditation may help.

Our take: keep the fan and the layers, because they cost nothing. But if the flashes run your day, go further than that.

The play

Try this: log your flashes

Note when each hot flash hits, what came before it, and how much it bothered you.

NIA² says this helps you make better decisions about managing your symptoms.

NIA² also points to My Menoplan, a tool built by NIA-funded researchers, to find coping and treatment strategies that fit you.

What doesn’t have proof

NIA² has a blunt section for this. Black cohosh, DHEA and soy isoflavones have not been shown to work for hot flashes, and some carry risks such as liver damage. Plant estrogens haven’t been consistently shown to work, and their long-term safety is unclear.

NIA’s² advice: always talk with your doctor before taking any herb or supplement.

When lifestyle isn’t enough

The Menopause Society¹ ranks hormone therapy as its strongest treatment for bothersome hot flashes, and says it’s considered first-line when the benefits outweigh the risks, particularly in early menopause. NIA² lists the risks too: heart attack, stroke, blood clots, breast cancer, gallbladder disease and dementia, varying with your age and with a history of hysterectomy. If it’s right for you, NIA says, it should be at the lowest dose and for the shortest time it’s needed, in consultation with a doctor.

The Menopause Society¹ adds that about half of women have hot flashes return when they come off hormone therapy, though symptoms typically ease over time.

If hormones aren’t a fit, there are two FDA-approved non-hormone medicines: a low-dose antidepressant of the SSRI class, and a newer drug that works in the part of the brain that regulates body temperature. Whether either suits you, and what side effects to watch for, is a call for your clinician.

When to get checked

NIA² says that if hot flashes bother you, there are steps you can take. Cleveland Clinic³ points out that hot flashes and night sweats can also be related to thyroid disorders, other conditions, or medications, so a new pattern is a good reason to ask.

See a clinician if any of these fit:

• Hot flashes or night sweats are disrupting your sleep, work or mood
• You have palpitations
• Your bleeding pattern is changing, and periods are increasing rather than tapering off
• The flashes started after a new medicine

Get checked if you have had no period for more than 12 months and then have any vaginal bleeding, even a small amount. The NHS⁴ says postmenopausal bleeding needs to be checked, because it can be a sign of cancer. Don’t wait on that one.

Next time the heat starts under your collarbone in a meeting, wear the cardigan anyway. The kind that comes off.