A sudden rush of heat from a woman’s chest to her head is called a hot flash. Hot flashes may be accompanied by heavy sweating and reddening of the head, neck and chest, or entire body. Hot flashes that occur at night when a woman is sleeping are referred to as night sweats as they commonly cause drenching sweats.

Hot flashes can range from a mild feeling of warmth to even, intense heat in the upper body. In some cases, they can be accompanied by:

• Flushed appearance
• Red, blotchy skin on the face, arms and neck
• A rapid heartbeat
• Mild to drenching perspiration
• A chilled feeling after the hot flashes pass

Most women find that hot flashes come in bursts that can last a few seconds or minutes, but some may last for up to 30 minutes. Hot flashes are frequently accompanied by profuse perspiration and sometimes heart palpations (rapid heart beat). Some women report feeling nauseous when they experience more intense hot flashes. They can occur several times an hour or just once or twice per day. When hot flashes occur at night (night sweats), they can wake a person from a sound sleep.

Hot flashes are most commonly associated with menopause, a change that occurs when a woman’s body no longer releases eggs, and her ovaries produce significantly lower amounts of the hormones estrogen and progesterone. As estrogen levels decline during this time, many women experience varying degrees of symptoms, including hot flashes.

Menopause typically occurs between the ages of 45 and 55 years, although it can occur earlier or later. Menopause is officially said to have occurred when a woman goes without a menstrual cycle (also known as a period) for 12 consecutive months and there are no other reasons for this change.

Although menopause usually occurs because of the natural aging process, other factors can trigger the event at younger ages, which in turn leads to hot flashes. Medical conditions that require surgery to remove both ovaries (bilateral oophorectomy) will cause premature menopause.

In addition, genetic factors and cancer treatments such as chemotherapy or radiation therapy to the pelvic area can cause early menopause. Chemical or surgically-induced menopause often causes severe hot flashes. Women requiring treatment with certain estrogen blockers for endometrial or breast cancer may also experience these symptoms.

There are about 37.5 million women reaching or currently at menopause (ages 40 to 59) in the United States, according to data collected as part of the U.S. census in 2000. According to the Food and Drug Administration (FDA), about 85 percent of women approaching or going through menopause have hot flashes. That roughly translates into nearly 32 million women experiencing hot flashes.

Many women experience hot flashes as a symptom of impending menopause during what is called a transitional period or perimenopause. Some women will have hot flashes for only a short time but the majority of women will have them for at least a year or more. There are women who go through perimenopause and menopause with no hot flashes.

Hot flashes are caused by changes in the way blood vessels relax and contract, and are typically associated with fluctuations in a woman’s estrogen levels. During the hot flash, the woman will suddenly feel her skin temperature begin to rise. Although she may initially feel quite warm, the heat lost by her body’s cooling mechanism (perspiration) will cause her core body temperature to drop below normal. For this reason, she may experience chills or even shivering afterward as the body attempts to restore a normal temperature.

The biological reasons for hot flashes are not completely understood. Most health experts believe that they are related to a decreasing level of estrogen, since hot flashes are most commonly linked to menopause. Hot flashes may be caused by fluctuating levels of other hormones that, in turn, affect the part of the brain (hypothalamus) that regulates body temperature. This process may cause the body to believe it is too hot even when it is a normal temperature. This signal tells the body to release the excess heat and it responds by dilating blood vessels in the head, face, neck and chest, causing a hot flash.

Hot flashes can be upsetting and frustrating for a woman, particularly if they are intense. However, there is no medical cause for concern as hot flashes are not a sign of a medical problem, but rather a normal biological reaction to fluctuating hormone levels in a woman’s body. Aside from menopause, hot flashes may be caused by breast cancer or its treatment.

Other factors that may contribute to hot flashes include:

• Chemotherapy-induced ovarian failure
• Estrogen-lowering medications
• Infertility medications (e.g., ovulation drugs)
  

Men can also experience hot flashes. Often the cause is either an infection or a side effect of certain medications. It can also be the result of undergoing androgen ablation therapy. It is considered fairly common among men treated for prostate cancer with GnRH agonists or by having their testicles removed. Physicians will often order a blood test to see if a testosterone deficiency is another reason for the hot flashes.