Hot flashes are most commonly a sign of the menopause transition, but they can also signal other conditions, including thyroid problems, infections, medication side effects, and certain cancers. About 57% of women between ages 40 and 64 experience hot flashes, making them one of the most widespread symptoms in midlife. Understanding what’s behind them matters because the cause shapes what you can do about it.
The basic mechanism is the same regardless of the trigger. When certain hormones drop or the brain’s temperature control center gets disrupted, the narrow range of body temperature your brain considers “normal” shrinks dramatically. A tiny uptick in core temperature that your body would normally ignore instead triggers a full cooling response: blood vessels near the skin dilate, blood rushes to the surface, and sweating kicks in. You feel a sudden wave of heat, usually across your face, neck, and chest, even though your actual body temperature barely changed.
Perimenopause and Menopause
The most common cause by far is the hormonal shift of perimenopause and menopause. Most women start noticing hot flashes in their 40s, though some begin in their 30s. During perimenopause, estrogen and progesterone levels swing unpredictably rather than declining in a smooth line. Those downward swings in estrogen trigger a surge of norepinephrine in the brain, which narrows the thermoneutral zone and sets off a hot flash. The hormonal ups and downs don’t fully settle until roughly 10 years after menopause.
How long hot flashes last varies more than most people expect. The old estimate of six to 24 months turns out to be far too short for many women. A large study tracking women over time found that women whose hot flashes began before their periods stopped had symptoms for an average of nine to 10 years. Women whose flashes didn’t start until after their final period averaged about three and a half years. Duration also varies by race and ethnicity: African American women reported the longest average duration at more than 11 years, while Japanese and Chinese women averaged roughly half that.
Thyroid Problems
An overactive thyroid gland (hyperthyroidism) can produce hot flashes that feel identical to menopausal ones. The thyroid communicates with the same part of the brain that controls body temperature, the hypothalamus. When the thyroid overproduces hormones, it can overstimulate that control center and trigger the same flushing and sweating response. If you’re younger than typical menopause age and experiencing frequent hot flashes, hyperthyroidism is one of the first things worth checking. A simple blood test can confirm or rule it out.
Medications and Cancer Treatment
Several categories of medication can cause hot flashes as a side effect. Hormone-blocking drugs used in breast and prostate cancer treatment are among the most common culprits. Chemotherapy, radiation therapy, certain antidepressants, opioid pain medications, and steroids can all trigger them as well. If your hot flashes started shortly after beginning a new medication, that timing is worth noting and discussing with whoever prescribed it.
Low Testosterone in Men
Hot flashes aren’t exclusive to women. Men’s testosterone levels decline gradually, about 1% per year after age 40, but this slow trickle rarely drops low enough to cause hot flashes on its own. The major exception is men receiving androgen deprivation therapy for prostate cancer. Between 70% and 80% of men on this treatment experience hot flashes, and the symptoms can be persistent. Men on temporary androgen deprivation usually see their flashes resolve within three to four months of stopping treatment, but men on long-term therapy often don’t. One study found over 40% of men still had hot flashes after more than eight years of treatment.
Infections and Fevers
Any infection that raises your body temperature can produce episodes that feel like hot flashes. Your immune system deliberately heats the body to fight off invaders, and the resulting temperature swings can mimic the flushing and sweating of hormonal hot flashes. Urinary tract infections, tuberculosis, HIV, heart valve infections, and bone infections can all cause this pattern. If your hot flashes come with fatigue, joint aches, chills, or a fever, an underlying infection is a real possibility.
Rare Causes
Carcinoid syndrome, a condition where a slow-growing tumor secretes excess serotonin, can cause intense flushing of the face, neck, and upper chest. This is uncommon, but the flushing episodes can look a lot like hot flashes. Neurological conditions that affect the autonomic nervous system, the network that regulates involuntary functions like temperature control, can also disrupt the body’s thermostat.
Even certain foods and drinks play a role for some people. Alcohol can trigger flushing through a genetic variation in how the body breaks down alcohol, particularly common in people of East Asian descent. Processed foods containing nitrites (hot dogs, deli meats) cause a similar reaction in people with nitrite sensitivity.
Hot Flashes and Heart Health
Research from the Study of Women’s Health Across the Nation (SWAN) has linked hot flashes to markers of cardiovascular risk in ways that go beyond coincidence. Women who reported hot flashes showed reduced blood vessel function and greater calcium buildup in the aorta compared to women without them, even after accounting for traditional heart disease risk factors like cholesterol and blood pressure. Women who experienced hot flashes early in the menopause transition also had thicker carotid artery walls, a measure associated with higher stroke and heart attack risk. The association between menopausal symptoms and coronary heart disease held up even after adjusting for standard risk factors, with a 28% higher relative risk.
This doesn’t mean hot flashes cause heart disease. But frequent or severe hot flashes, especially ones that start early in the transition, may be worth treating as a signal to pay closer attention to cardiovascular health.
Signs That Something Else Is Going On
Most hot flashes are a normal, if uncomfortable, part of hormonal change. But certain patterns suggest something beyond typical menopause. Unexplained weight loss alongside night sweats is a combination that warrants investigation. The same goes for hot flashes paired with a persistent cough, diarrhea, or a high fever. Night sweats that regularly wake you up or are soaking enough to require changing your sheets also deserve a closer look, particularly if you’re outside the typical age range for menopause or if the episodes started suddenly without an obvious hormonal explanation.