What are hot flashes? 

A hot flash (is a feeling of warmth that spreads over the body that begins, and is most strongly felt, in the head and neck regions.  Hot flashes are a common symptom experienced by women prior to, and during the early stages  of the menopausal transition. However, not all women approaching the menopause will develop hot flashes. 

What causes hot flashes? 

The complex hormonal changes that accompany the aging process, in particular the declining levels of estrogen as a woman approaches menopause, are thought to be the underlying cause of hot flashes. A disorder in thermoregulation (methods the body uses to control and regulate body temperature) is responsible for the sensation of heat, but the exact way in which the changing hormone levels affect thermoregulation is not fully understood. 

While  hot flashes are considered to be a characteristic  symptom of the menopausal transition, they can also occur in men, and in circumstances other than  the perimenopause in  women as a result of certain uncommon medical conditions that affect the process of thermoregulation. For example, the carcinoid syndrome results from a type of endocrine tumor that secretes large amounts of the hormone serotonin  and can cause  hot flashes. Hot  flashes can also develop as  a side effect of some medications  and can sometimes occur with severe infections or cancers that may be associated with fevers and/or night sweats. 

What are  the symptoms of hot flashes? 

• Hot flashes are typically brief, lasting from about 30 seconds to a few minutes. 
• Redness of the skin, known as flushing, may accompany hot flashes. 
• Excessive perspiration (sweating)  can also occur; when hot flashes occur during sleep they may  be accompanied by night sweats. 

The timing of the onset of hot flashes in  women approaching menopause is variable. 

• While not all women will experience hot flashes, many normally menstruating women will begin experiencing  hot flashes even several years prior to the cessation of menstrual periods. 
• It is impossible to predict if  a woman will  experience hot flashes, and if she does, when they will begin. 
• About 75% of women experience hot flashes at some point  in the menopausal transition. 

How are hot flashes diagnosed? 

Hot flashes are symptoms, not  a medical condition. Through a thorough medical history, the healthcare practitioner will usually be able to determine whether a woman is having hot flashes.  The patient will be asked to describe the hot flashes, including how often and when they occur, and if there are other associated symptoms. A physical examination together with the medical history can help determine the cause  of the  hot flashes and direct further testing if necessary. 

Blood tests may be performed if the diagnosis is unclear, either  to measure hormone levels  or to look for signs  of other conditions (such as infection) that could be responsible for  the hot flashes. 

What is the treatment  for hot flashes? 

There are a variety of treatments for hot flashes such as: 

• hormone therapy, 
• bioidentical hormone therapy, 
• other drug treatments, 
• complementary and alternative treatments, 
• phytoestrogens, 
• black cohosh, and 
• other alternative therapies. 

Some of these have not been proven by clinical studies, nor are they approved by the FDA. 

Hormone Therapy 

Traditionally, hot flashes have been treated with either oral  or transdermal (patch) forms of estrogen. Hormone therapy (HT), also referred to as hormone replacement therapy (HRT)  or postmenopausal hormone therapy (PHT), consists of estrogens alone or a combination of estrogens and progesterone (progestin). All available prescription estrogen medications, whether oral or transdermal; are  effective in reducing  the frequency  of hot flashes and their severity. Research indicates  that these medications decrease  the frequency of hot flashes  by about 80% to 90%. 

However, long-term studies (the NIH-sponsored Women's Health Initiative, or WHI) of women receiving combined hormone therapy with both estrogen and progesterone were halted when it was discovered that these women had an increased risk for  heart attack, stroke, and breast cancer when compared with women who did not receive  hormone therapy. Later studies of women taking estrogen  therapy alone showed that estrogen was associated with an increased risk  for stroke, but  not for heart attack or breast cancer. Estrogen therapy alone, however, is associated  with an increased risk  of developing endometrial cancer (cancer of the lining of the uterus) in postmenopausal women who  have not had their uterus surgically removed. 

More recently, it has been noted that the negative effects associated  with hormone therapy were described in older women who were years beyond menopause, and  some researchers have suggested that these negative outcomes might be lessened or prevented if hormone therapy was given to younger women (prior to or around  the age of menopause) instead of women years beyond menopause. 

The decision in regard  to starting or continuing hormone therapy, therefore, is an individual one in which  the patient and doctor must take into account the inherent risks and benefits  of the treatment along with each woman's own medical history. It  is currently recommended that if  hormone therapy is used, it should be used at the smallest effective dose  for the shortest possible time. 

Bioidentical hormone therapy 

There has been increasing interest in recent years in the  use of so-called "bioidentical" hormone therapy for perimenopausal women. Bioidentical hormone preparations are medications that contain  hormones that have  the same chemical formula as those made naturally in  the body. The hormones are created in a laboratory by altering compounds derived from naturally-occurring plant products. Some  of these so-called bioidentical hormone preparations are U.S. FDA-approved  and manufactured by drug companies, while others are made at special pharmacies called compounding pharmacies, which make the preparations on a case-by-case basis  for each patient. These individual preparations are not regulated by the FDA, because compounded products are not standardized. 

Advocates  of bioidentical hormone therapy argue  that the products, applied as creams or gels, are absorbed into the body in their active form without the need  for "first pass" metabolism in the liver,  and that their use may avoid potentially dangerous side effects of synthetic hormones used in conventional hormone therapy. However, studies to establish the long-term safety  and effectiveness  of these products have not been carried out. 

Other drug  treatments

• The selective serotonin reuptake inhibitor (SSRI) medications have been shown be effective in reducing menopausal hot flashes. These drugs are generally used in the treatment of depression and anxiety as well as other conditions The SSRI that has been tested most extensively in the treatment of hot flashes is venlafaxine (Effexor), although other SSRI drugs may be effective as well. 
• Clonidine (Catapres) is an anti-hypertensive drug that can relieve hot flashes in some women. Clonidine is taken either by pill or skin patch  and decreases blood pressure. Side effects of clonidine can include dry mouth, constipation, drowsiness, or difficulty sleeping. 
• Gabapentin (Neurontin), a drug primarily used  for the treatment of seizures, has also been effective in treating hot flashes. 
• Megestrol acetate (Megace) is  a progestin that is sometimes prescribed over a short-term  to help relieve hot flashes, but this drug  is not usually recommended as a first-line treatment  for hot flashes. Serious side effects can occur if  the medication is abruptly discontinued. Megestrol may have  the side effect of weight gain. 
• Medroxyprogesterone acetate (Depo-Provera) is another progestin drug  and is administered by injection  to treat hot flashes. It may lead to weight gain as well as bone loss. 

Complementary and alternative treatments 

Some women report that exercise programs or relaxation methods have helped to control hot flashes, but controlled studies have failed to show a benefit  of these practices in relieving the  symptoms of  hot flashes. Maintaining a cool sleep environment and  the use of cotton bedclothes can help ease some of the discomfort associated with hot flashes and associated night sweats. 

Many women turn to alternative therapies, including herbal products, vitamins, plant estrogens, and other substances,  for the treatment  of hot flashes. Doctors can be reluctant to recommend alternative treatments because these nonprescription products are not regulated by  the FDA (like prescription medications), and their ingredients and strength can vary from manufacturer to manufacturer. For products that are not regulated by the FDA, testing and proof  of safety is not required  for marketing of these products. Long-term, scientifically controlled  studies for these products are either lacking or have not proved the safely and effectiveness  of many of the so-called natural or alternative remedies. 

Some alternative treatments, however, have been evaluated in well-designed clinical trials. Alternative treatments that have been scientifically studied with some research include phytoestrogens (plant estrogens, isoflavones), black cohosh, and vitamin E. 

Phytoestrogens 

Isoflavones are chemical compounds found in soy and other plants (such as chick peas and lentils) that are phytoestrogens, or plant-derived estrogens. They have a chemical structure that is similar to the estrogens naturally produced by the body, but their effectiveness as an estrogen has been determined to be much lower than true estrogens. 

Some studies have shown that these compounds may help relieve hot flashes and other symptoms  of menopause. In particular, women who have had breast cancer  and do not want to take hormone therapy (HT) with estrogen sometimes use soy products for relief of menopausal symptoms. However, some phytoestrogens can actually have anti-estrogenic properties in certain situations, and the overall risks of these preparations have not yet been determined. 

There is also a perception among many women that plant estrogens are "natural" and therefore safer than hormone therapy, but this has never been proven scientifically. Further research is needed to fully characterize the safety and potential risks of phytoestrogens. 

Notes: Dr. Nelson Crumfield

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EditText of this page (last edited July 10, 2010)