Vasomotor Symptoms of Menopause

Candace Cooley has treated menopause related concerns throughout her gynecologic career, hot flashes prominent among them, and a common belief about them, once shared by researchers, holds that they are a brief nuisance clustered around the final period. The belief was reasonable. A University of Pittsburgh researcher told CBS News in 2016 that the field used to think these symptoms lasted three to five years, close to the last period, before long term data showed that they typically persist seven to ten years and begin at different times for different women.⁹ Flushes of heat by day and drenching sweats by night share one clinical name, vasomotor symptoms, which points to the blood vessels that widen during an episode.

What they are and how long they last

The Menopause Society describes a hot flash as a sudden, intense feeling of heat in the upper body, especially the face, neck and chest, usually lasting one to five minutes and sometimes bringing sweating, chills, anxiety or a racing heart. Night sweats are the same event during sleep. The society puts the share of women affected at up to 80 percent, with a mean duration of seven to ten years, and notes that the symptoms can disturb sleep and mood. Severity runs from a mild sensation of warmth without sweating to episodes intense enough to stop a woman in the middle of what she is doing.⁵ Science News likewise reports that up to 80 percent of women have them at some point in the transition and that many have them for more than seven years.¹ A 2017 Washington Post report gave a figure of more than 70 percent of women.¹⁰

Timing varies more than the old belief allowed. The study described by CBS followed nearly 1,500 women for a median of 15 years and found four patterns: symptoms that began about 11 years ahead of the last period and eased after it, symptoms that began near the final period and eased later, early and frequent symptoms, and symptoms that stayed infrequent throughout. Weight, education, race and health habits were associated with the patterns, though the authors stressed these were associations rather than causes.⁹ The National Institute on Aging adds that African American and Hispanic women have hot flashes for more years than White and Asian women.⁶ For some women the symptoms never quite end. A Mayo Clinic study summarized by ScienceDaily gathered data from nearly 5,000 women and found a significant share reporting hot flashes into their 60s, 70s and 80s, more often after surgical or induced menopause.⁴

Figure

Four patterns of hot flashes

1. 01
   Early onsetSymptoms begin about 11 years before the final period and decline after menopause
2. 02
   Onset near the final periodSymptoms start around the last period and decline later
3. 03
   Early and frequentSymptoms start early and come often
4. 04
   Persistently lowSymptoms stay infrequent throughout the transition

Some risk factors are known. The Menopause Society lists more abdominal fat in younger women and those early in the transition, and current or past smoking. Women who lose both ovaries to surgery before natural menopause often have hot flashes right after the operation, and theirs tend to be more frequent and more severe.⁵

The symptoms may also carry information about health. In 2024 the American Heart Association listed vasomotor symptoms among the midlife changes that can bear on cardiovascular health, while stressing that menopause does not itself cause heart disease.⁷ Work from a University of Pittsburgh laboratory, covered by CNN in 2023, has linked frequent or lasting early hot flashes with heart attack, stroke and heart failure at rates 50 to 80 percent higher, daytime flashes with raised C reactive protein, and night sweats with an unfavorable amyloid profile in the blood. Those links, the society’s medical director cautioned in that report, identify women at higher risk; they do not show that the flashes cause harm.³ The cardiac side is followed in menopause and heart disease, and the years in which the symptoms usually begin in perimenopause.

Much of this knowledge is recent. NIH MedlinePlus Magazine traces it through a sequence of federal studies: the Women’s Health Initiative, launched in 1991 with more than 161,000 women; the SWAN study of about 3,300 more diverse and younger women from 1994; trials from 2008 that found some antidepressants reduce hot flashes; and a study under way since 2016 of how vasomotor symptoms relate to brain aging.⁸ The first of those is the subject of the Women’s Health Initiative.

How the brain sets off a hot flash

The cause long resisted explanation. In 2017 a UCLA professor of medicine told The Washington Post simply that the answer was not known.¹⁰ The picture has since sharpened. Science News describes hot flashes as the result of a narrowing in the body’s range of temperature tolerance, so that a small rise in core temperature feels like a blast of heat and sets off exaggerated cooling: sweating and flushing from widened blood vessels. Research on a group of neurons in the hypothalamus, called KNDy neurons, explains the narrowing. As estrogen declines, these neurons grow and become overactive, releasing a chemical messenger that binds a receptor on the neurons themselves and on nearby temperature control neurons.¹

Figure

How a hot flash starts

1. 01
   Estrogen fallsEstrogen levels decline across the menopause transition
2. 02
   KNDy neurons changeA group of neurons in the hypothalamus grows and becomes overactive
3. 03
   Messenger releasedOne chemical messenger binds a receptor on these neurons and on nearby temperature control neurons
4. 04
   Range narrowsThe body's band of comfortable temperature narrows, so a small rise feels like a blast of heat
5. 05
   Cooling responseBlood vessels dilate and sweating starts, producing flushing and perspiration

A 2026 Pharmacy Times panel explains that KNDy neurons normally help regulate both reproductive hormone release and body temperature, and that after menopause they act erratically on the temperature center. Of three related receptor subtypes, the panel identifies NK3 as the central target for hot flash relief, with NK1 adding effects on sleep and NK2 playing a smaller role.² That science produced a new class of medicine. Science News reports that fezolinetant, which blocks the NK3 receptor, was approved in 2023, and that a second drug, elinzanetant, which also acts on a receptor linked to sleep, reduced hot flash frequency by at least half in more than 70 percent of women by week 12 in two phase 3 trials, against more than 40 percent on placebo. The trials enrolled women aged 40 to 65 with at least 50 moderate to severe hot flashes a week; by 26 weeks, 82 percent of those on the drug throughout had reached that threshold, and headache and fatigue were the most common side effects. A strong placebo response is typical of hot flash trials, which is why the comparison matters.¹

Figure

A nonhormonal drug against placebo

• Elinzanetant70
• Placebo40

Hormone therapy remains the most effective treatment. The Menopause Society calls it an approved first line therapy whose benefits clearly outweigh its risks when used in early menopause for hot flashes, night sweats and disturbed sleep, delivered as pills, patches, sprays, gels or a vaginal ring that reach the whole body. It also notes that about half of women see hot flashes return, at least for a time, when they stop.⁵ The Mayo Clinic study found that women using hormones were less likely to report moderate to severe symptoms, and noted that major medical societies advise against stopping hormone therapy on the basis of age alone.⁴ Science News lists women who are usually poor candidates, among them those with estrogen sensitive breast cancer, past blood clots, a history of stroke or migraine with aura.¹ The institute lists the risks, among them heart attack, stroke, blood clots, breast cancer, gallbladder disease and dementia, which vary with age and with whether a woman has had a hysterectomy.⁶ The treatment is described in full in menopause hormone therapy.

For women who cannot or prefer not to use hormones, the society lists two medicines approved specifically for hot flashes, low amount paroxetine and fezolinetant, along with other medicines used off label, and names weight loss, cognitive behavioral therapy and clinical hypnosis as nonprescription approaches with evidence behind them. Many other remedies, from supplements to paced breathing, have limited data or failed in trials.⁵ The institute adds everyday measures such as a cooler bedroom, layered clothing and a portable fan, and notes early research on hypnotherapy and mindfulness.⁶ The right choice differs from woman to woman and is worked out with a clinician who has her full history. Set out side by side, the two broad routes compare as follows.

Figure

Hormonal and nonhormonal treatment compared

	Hormone therapy	Nonhormonal medicine
Standing	Approved first line therapy and the most effective treatment	Two medicines approved for hot flashes, others used off label
Examples	Estrogen as pills, patches, sprays, gels or a vaginal ring	Low amount paroxetine, fezolinetant, some antidepressants, gabapentin, oxybutynin
Often suited to	Early menopause, where benefits outweigh risks	Women who cannot or prefer not to use hormones, including after breast cancer