Hot flashes, a common symptom of menopause and perimenopause, are typically experienced as a feeling of intense heat with sweating and rapid heartbeat, and may typically last from two to thirty minutes for each occurrence. The sensation of heat usually begins in the face or face and chest, although it may appear elsewhere such as the back of the neck, and it can spread throughout the whole body. Some women pass out if the effects are strong enough. In addition to being an internal sensation, the surface of the skin, especially on the face, becomes hot to the touch. This is the origin of the alternative term "hot flush," since the sensation of heat is often accompanied by visible reddening of the face. Excessive flushing can lead to rosacea.
The hot-flash event may be repeated a few times each week or constantly throughout the day, with the frequency reducing over time. Hot flashes may begin to appear several years before menopause starts and last for years afterwards. Some women undergoing menopause never have hot flashes. Others have mild or infrequent flashes. The worst sufferers experience dozens of hot flashes each day. In addition, hot flashes are often more frequent and more intense during hot weather or in an overheated room, the surrounding heat apparently making the hot flashes themselves both more probable and more severe.
Severe hot flashes can make it difficult to get a full night's sleep (often characterized as insomnia), which in turn can affect mood, impair concentration, and cause other physical problems. When hot flashes occur at night, they are called "night sweats." As estrogen is typically lowest at night, some women get night sweats without having any hot flashes during the daytime
Hot flashes in men could be a possible sign of low testosterone. Men who are castrated can also get hot flashes. Men with prostate cancer who are undergoing hormone therapy with antiandrogens, also known as androgen antagonists, which reduce testosterone to castrate levels, can have hot flashes as the most common side effect