A hot flash is a brief feeling of intense warmth and sweating. Hot flashes commonly occur in women around the time of menopause.
Researchers do not know exactly what causes hot flashes. Current theories suggest hot flashes are due to a menopause-related drop in the body's level of female hormones called estrogens. This drop affects the hypothalamus, an area of the brain that regulates body temperature. In a hot flash, the hypothalamus seems to sense that your body is too hot even when it is not, and tells the body to release the excess heat. One way the body does this is to widen (dilate) blood vessels, particularly those near the skin of the head, face, neck and chest. Once the blood vessels return to normal size, you feel cool again.
Hot flashes affect about 85% of women during the years immediately before and after menopause. Menopause usually occurs around age 51, but hot flashes can begin as early as 2 to 3 years before the last menstrual period. Hot flashes can last for 6 months to as long as 15 years after the final period. The average is two years. Some women have only a few episodes a year, while others have as many as 20 episodes a day. Hot flashes occur in women who experience natural menopause, as well as in women who undergo menopause because their ovaries have been removed surgically or because they take medications that lower estrogen levels. These medications include gonadotropin-releasing hormone agonists, such as leuprolide (Lupron) or danazol (Danocrine) that lower estrogen levels.
Although hot flashes usually are considered a female problem, men can have hot flashes if their levels of the male sex hormone testosterone drop suddenly and dramatically. For example, hot flashes occur in 75% of men with prostate cancer who have surgery to remove the testes (orchiectomy) or who take medication to decrease testosterone levels.
Symptoms that mimic hot flashes can occur in both men and women who have a tumor of the hypothalamus or pituitary gland, certain serious infections such as tuberculosis or HIV, alcoholism or thyroid disorders. Symptoms that are similar to hot flashes also can be a side effect of the food additive monosodium glutamate (MSG), or of certain medications, particularly nitroglycerin (sold under many brand names), nifedipine (Procardia, Adalat), niacin (numerous brand names), vancomycin (Vancocin) and calcitonin (Calcimar, Cibacalcin, Miacalcin).
A hot flash begins as a sensation of intense warmth in the upper body, followed by skin redness (flushing), drenching perspiration, and finally a cold, clammy feeling. Typically, these symptoms begin at the head and spread downward toward the neck and chest. They last from 30 seconds to 5 minutes. The average is 4 minutes. Hot flashes can be accompanied by other uncomfortable sensations, such as heart palpitations, a pressure feeling in the head, or feelings of dizziness, faintness or weakness. When hot flashes occur during the night, they can cause sleeplessness (insomnia), resulting in poor concentration, memory problems, irritability and exhaustion during the day.
After noting your age, your doctor will ask you whether you are still having regular menstrual periods. If you are not, your doctor will ask the approximate date of your last period. If you are still menstruating, the doctor will want to know whether there is anything unusual about the timing of your periods or the amount of blood flow. Your doctor will ask whether you are experiencing any other symptoms that may be related to decreased estrogen, such as vaginal dryness, pain or discomfort during intercourse or urinary incontinence. Finally, your doctor will review your medical history, your gynecological history and the types of medications you are taking. This is to make sure your symptoms are hot flashes and not the result of a medical or gynecological illness or a side effect of medication.
In most cases, your doctor can confirm that your hot flashes are related to menopause by reviewing your menstrual history and conducting a physical exam, including a pelvic exam. Your doctor may order a blood test to measure serum levels of follicle stimulating hormone (FSH), which are high during menopause.
In most women who undergo natural menopause, hot flashes subside within 2 to 5 years after the last menstrual period. In a small number of women, however, hot flashes can continue for 8 to 15 years after the last menstrual period.
There is some evidence that women who go through menopause due to surgery may have more severe hot flashes for more years than women who go through natural menopause.
Hot flashes related to menopause cannot be prevented. However, the following lifestyle changes may help to make hot flashes less severe or less frequent:
- Drink a glass of cool water at the beginning of a hot flash. This seems to lessen discomfort in some women. Also, be sure to drink enough water, usually six to eight glasses per day.
- Avoid drinking beverages that contain caffeine or alcohol, since these can make hot flashes more uncomfortable.
- Cut down on red wine, chocolate and aged cheeses. They contain a chemical that can trigger hot flashes by affecting the brain's temperature control center.
- Don't smoke. Smoking can make hot flashes worse.
- Wear loose, comfortable clothing made of cotton to help absorb perspiration.
- Dress in layers, so that you can remove some clothing if you suddenly feel hot.
- Lower your home thermostat to keep your house cool. At work, open a window or use a small portable fan.
- At night, use lightweight blankets that can be removed if hot flashes wake you up.
- Regular vigorous exercise during which endorphins are produced may also decrease hot flashes.
Estrogen is the most effective medication available to relieve hot flashes. Short-term use of low-dose estrogen may be prescribed, with or without progesterone. If a woman still has her uterus, estrogen is prescribed together with progesterone to decrease the small risk of uterine cancer. Estrogen used alone causes growth of the uterine lining but adding progesterone prevents or decreases this growth, thereby decreasing the risk of developing uterine cancer. If your uterus was removed, then only estrogen is required.
Estrogen can be taken as a pill or administered through a skin patch to treat hot flashes. Estrogen can be applied directly to the vagina as a cream, suppository, or ring to treat vaginal symptoms. Progesterone can be taken as a pill or a patch or as a vaginal suppository. Women who use estrogen should use the smallest dose that relieves hot flashes.
Because of potential side effects and dangers of hormone therapy, many women choose not to use estrogen in any form. Estrogen had been thought to reduce the incidence of heart attack and stroke in postmenopausal women, but clinical trials, known as the Women's Health Initiative, have thrown doubt on that theory. This research shows that women who use hormone therapy after menopause may be more at risk of heart attack and stroke and breast cancer than women who do not. Based on this study, the use of estrogen and progesterone is no longer recommended for the prevention of heart disease.
Alternative medications to help decrease the intensity of hot flashes include clonidine (Catapres), gabapentin (Neurontin), or antidepressants such as venlafaxine (Effexor), paroxetine (Paxil), fluoxetine (Prozac) and sertraline (Zoloft). For women who have undergone surgical menopause and have unusually severe hot flashes, some studies have shown that a combination of estrogen and androgen may be effective.
Several nonprescription herbal remedies have been proposed as natural ways to prevent or treat hot flashes. Many of these treatments have not been studied in large clinical trials. Although black cohosh has been previously promoted as a treatment for hot flashes, a study reported in the December 2006 Annals of Internal Medicine found that the root was no better than a placebo.
Call your family doctor or gynecologist if hot flashes bother you at home or at work, prevent you from getting a good night's sleep, cause you serious discomfort or otherwise interfere with your quality of life.
In more than 95% of women, the use of low-dose estrogen medication is effective in treating hot flashes. However, it may take two to four weeks of treatment before improvement is noticeable. With or without using estrogen, hot flashes gradually diminish and disappear completely with time.
American College of Obstetricians and Gynecologists
P.O. Box 96920
Washington, DC 20090-6920
National Women's Health Information Center (NWHIC)