Hot flushes are caused by changes in the brain’s temperature-control system, most commonly triggered by falling estrogen levels during menopause. Up to 80% of middle-aged women experience them, and a major longitudinal study found that symptoms last a median of 7.4 years, far longer than the “few years” doctors once assumed.
But menopause isn’t the only cause. Medications, medical conditions, hormonal treatments, and even certain foods can trigger flushes in both women and men.
How Your Brain’s Thermostat Goes Haywire
Your brain has a built-in thermostat in a region called the hypothalamus. It maintains your body temperature within a comfort zone: if you get too warm, it triggers sweating and blood vessel dilation to cool you down; if you get too cold, it triggers shivering. In people who don’t experience hot flushes, this comfort zone is fairly wide, so minor temperature shifts don’t set off any alarms.
When estrogen levels drop, that comfort zone narrows dramatically. A tiny increase in core body temperature that would normally go unnoticed now crosses the upper threshold, and your brain reacts as though you’re overheating. Blood vessels near the skin dilate rapidly, your heart rate jumps by 5 to 10 beats per minute, and your body temperature spikes by 1 to 3 degrees. Sweat follows as your body tries to dump heat it doesn’t actually need to lose. The whole episode typically lasts a few minutes, but it can leave you flushed, damp, and uncomfortable for longer.
The narrowing of this thermoregulatory zone appears to involve changes in serotonin signaling. When estrogen drops, serotonin pathways in the hypothalamus become less active, which disrupts the brain’s ability to accurately read and respond to temperature. This is why some treatments for hot flushes target brain chemistry rather than hormones directly.
Menopause Is the Most Common Cause
The sharp decline in estrogen during perimenopause and menopause is responsible for the vast majority of hot flushes. They can begin years before your last period, during the transition phase when hormone levels fluctuate unpredictably, and continue well into postmenopause. The SWAN study, which tracked a diverse group of 1,449 women with frequent hot flushes, found that some women experienced symptoms for up to 14 years.
Not every woman going through menopause gets hot flushes, and researchers still don’t fully understand why some women are more affected than others. What’s clear is that the speed and degree of estrogen withdrawal matters. Surgical menopause, where both ovaries are removed, tends to produce more severe and sudden flushes than natural menopause because the hormone drop is abrupt rather than gradual.
Medications That Trigger Flushes
Several types of medication cause hot flushes by lowering hormone levels in the body. Aromatase inhibitors, commonly prescribed after breast cancer to block estrogen production, are among the most frequent culprits. Hormone-blocking drugs used in prostate and breast cancer treatment work by suppressing estrogen, progesterone, or testosterone, and hot flushes are one of the most reported side effects.
Gonadotropin-releasing hormone blockers, used for conditions ranging from endometriosis to prostate cancer, also cause flushes by shutting down the body’s sex hormone production. Some antidepressants and opioid medications can trigger flushes as well, though through slightly different pathways.
Medical Conditions Beyond Menopause
When hot flushes don’t respond to standard treatments or occur outside the typical menopausal age range, other medical conditions may be responsible. Thyroid problems, particularly an overactive thyroid, can produce flushing and heat intolerance that closely mimic menopausal hot flushes.
Rarer causes include carcinoid syndrome (where tumors release chemicals that dilate blood vessels), pheochromocytoma (an adrenal gland tumor), medullary carcinoma of the thyroid, and certain pancreatic or kidney tumors. Systemic mast cell disease, in which immune cells release excess histamine, can also cause episodes of flushing. Neurological conditions and spinal cord injuries are additional, less common causes.
These conditions are uncommon, but they’re worth knowing about. Flushes that don’t fit the typical pattern, that come with other unusual symptoms like diarrhea or dramatic blood pressure swings, or that don’t respond to hormone therapy warrant further investigation.
Hot Flushes in Men
Men experience hot flushes too, most commonly as a side effect of androgen deprivation therapy for prostate cancer. Between 70% and 80% of men receiving this treatment develop flushes, because the therapy works by drastically reducing testosterone levels. The mechanism is essentially the same as in women: a sharp drop in sex hormones disrupts the brain’s temperature regulation.
Low testosterone from other causes can also produce flushes in men, though this is less well studied. The experience is similar to what women describe: a sudden wave of heat, flushing of the face and chest, sweating, and sometimes a chill afterward.
Everyday Triggers That Make Flushes Worse
If you’re already prone to hot flushes, certain everyday factors can set off individual episodes or make them more intense. These triggers don’t cause the underlying condition, but they push your already-narrowed thermostat past its threshold.
- Spicy foods and sugar can provoke a flush within minutes of eating
- Caffeine is a common trigger, and switching to decaf or herbal tea helps some people
- Alcohol dilates blood vessels and can set off flushing directly
- Warm environments, including hot baths, heated rooms, and exercising outdoors in summer
- Stress and strong emotions can trigger flushes through the nervous system’s effect on blood vessels
Practical steps like keeping your bedroom cool at night, avoiding hot showers, and skipping the hairdryer can reduce the frequency and intensity of episodes. These adjustments won’t eliminate flushes, but they remove the extra push that tips your body past its narrowed comfort zone.
How Hot Flushes Are Treated
Systemic estrogen therapy remains the most effective treatment for menopausal hot flushes. It works by restoring the hormone levels that keep the brain’s thermostat functioning within a normal range. For women who can safely take it, hormone therapy significantly reduces both the frequency and severity of episodes.
For people who can’t or prefer not to use hormones, there are now FDA-approved alternatives. Fezolinetant is the first in a newer class of drugs that works directly in the brain by blocking a receptor involved in temperature regulation, rather than replacing hormones. In clinical trials, it reduced hot flushes at both tested doses compared to placebo. Paroxetine, a low-dose antidepressant, is also FDA-approved specifically for hot flushes, though it shouldn’t be combined with tamoxifen. Other antidepressants and a nerve-pain medication called gabapentin have shown effectiveness for many women as well.
The right approach depends on what’s causing the flushes, how severe they are, and your broader health picture. For flushes caused by cancer treatment or medical conditions, the strategy may involve addressing the underlying cause or using non-hormonal options tailored to the situation.