They're often described as a sudden feeling of heat that seems to come from nowhere and spreads throughout the body. You might also experience sweating, palpitations, and flushing of the face.
Some women only have occasional hot flushes that don't really bother them, while others can have many a day, and find them uncomfortable, disruptive and embarrassing.
Hot flushes can start a few months or years before your periods stop (before you start the menopause), and usually continue for several years after your last period.
Causes of hot flushes
Hot flushes usually affect women who are approaching the menopause and are thought to be caused by changes in your hormone levels affecting your body's temperature control.
They can happen without warning throughout the day and night, but can also be triggered by:
Is a hot flush anything to worry about?
Hot flushes are usually harmless. But you should talk to your GP if you're having other symptoms as well, such as feeling generally unwell, fatigue, weakness, weight loss or diarrhoea.
What does a hot flush feel like?
Women often describe a hot flush as a creeping feeling of intense warmth that quickly spreads across your whole body and face "right up to your brow".
It typically lasts for several minutes. Others say the warmth is similar to the sensation of being under a sun bed, or feeling hot "like a furnace".
The website Healthtalk.org has several videos where women describe what a hot flush feels like.
Treatments for hot flushes
Many women learn to live with menopause-related hot flushes, but if they're really bothering you and interfering with your day to day life, talk to your GP about treatments that may help.
The most effective treatment for hot flushes is hormone replacement therapy (HRT), which usually completely gets rid of them. Your doctor will talk to you about the benefits and risks of using HRT.
If you've had a type of cancer that's sensitive to hormones, such as breast cancer, your doctor won't recommend HRT and will talk to you about alternatives.
Other medicines have been shown to help, including vitamin E supplements, some antidepressants, and a drug called gabapentin, which is usually used to treat seizures.
Find out more about treatment for hot flushes and other menopausal symptoms.
Tips for reducing hot flushes
You can try these tips to ease your symptoms:
cut out or reduce coffee and tea
keep the room cool and use a fan (electric or handheld) if necessary
if you feel a flush coming on, spray your face with cool water or use a cold gel pack (available from pharmacies)
wear loose layers of light cotton or silk clothes so you can easily take some clothes off if you overheat
have layers of sheets on the bed rather than a duvet so you can remove them as you need to
cut down on alcohol
sip cold or iced drinks
have a lukewarm shower or bath instead of a hot one
if medicine is causing your hot flushes, talk to your doctor about other ways you can take it to avoid this side effect
Complementary therapies for hot flushes
Women often turn to complementary therapies as a "natural" way to treat their hot flushes.
There have been small studies indicating that acupuncture, soy, black cohosh, red clover, pine bark supplement, folic acid, and evening primrose oil may help reduce hot flushes.
But the research is patchy, the quality of the products can vary considerably, and the long-term safety of these therapies isn't yet known.
It's important to talk to your doctor before you take a complementary therapy because it may have side effects (for example, liver damage has been reported with black cohosh) or mix badly with other medicines you're taking (women taking anticoagulants shouldn't take red clover).
Be aware, too, that soy and red clover contain plant oestrogens so may be unsafe for women who have had breast cancer.
Read more about complementary therapies and whether they work.