Most women will experience hot flashes at some time in their lives. They may be quite mild, or so severe that they are disabling. Hormone treatment works, but recent concern about the ill effects of hormone replacement therapy (HRT) has led to examination of possible alternatives . . .

Introduction

Although almost all women will get hot flashes (or hot flushes, as they are called in the UK) at some time in their lives, little is really known about how they are caused. Recent findings on the risks of hormone replacement therapy (HRT) have renewed interest in this, so that new treatments can be developed. Here's a summary from a Lancet review on the subject.

What are hot flashes?

Hot flashes are symptoms of feeling hot, with reddening of the skin and a fall in body temperature; there may also be sweating, palpitations, anxiety, irritability, and even feelings of panic. One woman in ten reports them as being 'almost intolerable'. How often they occur, and for how long, varies from person to person; a few seconds to ten minutes, and every hour to several times a week.

More than three women in four have hot flashes around the time of menopause, which last about a year; and a third of postmenopausal women have symptoms lasting 5 years, in some cases even longer. Hot flashes are more likely in women with low estrogen levels, low bodyweight, smokers, African-Americans, and those who undertake little physical activity; an early or an abrupt menopause (e.g. if it is caused by chemotherapy, or irradiation of the ovaries) is also a risk factor.

Hot flashes are associated with depression, nervousness, and insomnia; there may also be loss of libido. Are hot flashes associated with breast cancer? That's difficult to decide, as most such breast cancers occur in women over 50, and HRT is usually stopped when the cancer is diagnosed. Moreover, many breast cancer treatments include measures that may induce menopause - e.g. chemotherapy or endocrine therapy. Use of drugs known as serotonin receptor modulators and aromatase inhibitors are also associated with an increased likelihood of hot flashes.

What happens in the body?

It seems most probable that symptoms occur because of there is a decrease in estrogen levels, which can affect brain substances called neurotransmitters that control the body temperature. Exactly how the changes in hormone levels achieve this effect is unknown, to date. The substance serotonin may play an important role.

Treatment choices

A large number of non-medical treatments have been used, with variable degrees of success. To treat the symptoms, air conditioners, fans, and cold water are often used to make sufferers more comfortable. Many doctors advise lifestyle changes - exercise, diet, stopping smoking. Others advise 'behavioral interventions', including meditation, applied relaxation, biofeedback, and paced respiration. Not many of these approaches have been proved to be effective.

One of the problems in evaluating treatments for hot flashes is the relatively high 'placebo response'. As many as 20%-30% of people in a clinical study can have a reduction in the frequency and severity of hot flashes when given a placebo, i.e. a dummy tablet.

Very few good clinical studies have been done with medications for hot flashes. Those considered acceptable by the authors of this review are summarized in the following table:

* 'selective serotonin reuptake inhibitors', such as fluoxetine (Prozac®) and sertraline (Zoloft®)

In this selection, the 'placebo response' ranged between 20% and 38%.

The most studies have been done with estrogen, with results showing that hot flashes are reduced two to five times more often than with a placebo.
Unfortunately, results from several large studies have recently shown that HRT carries an increased risk breast cancer, as well as other bad effects, and its use is now limited (see the first link below).

Progestin is also effective in reducing hot flashes when give as a skin cream, oral tablets, or a vaginal gel. Side effects include vaginal bleeding in about 30% of women, weight gain, and blood clots in leg veins. The male hormone, androgen, given alone, or in combination with estrogen, has been shown to be effective, but it carries the risk of weight gain, bloating, growth of hair on the face and body, and acne.

Other drug approaches

Clonidine is an older drug that's about twice as effective as placebo in treating hot flashes. Side effects include a dry mouth, constipation, and low blood pressure on standing, which may lead to dizziness or fainting.

The serotonin drugs (selective serotonin-reuptake inhibitors, or SSRIs) are also about twice as effective as placebo in reducing hot flashes. However, they can cause a range of side effects: feeling generally unwell, sedation, agitation, headache, nausea, and loss of appetite. Sexual problems occur in as many as 15% of patients.

Alternative medicine?

As shown in the table above, vitamin E, soy, and black cohosh do not seem superior to placebo in well-controlled clinical studies. Ginseng, red clover, and Chinese herbal remedies have also proved disappointing when studied carefully.

Those alternative treatments that seem to be more effective than placebo mimic estrogen's beneficial effects; longer-term studies are needed to see if these alternatives are, in fact, any safer than estrogens.

Comment

Hot flashes are very common, but their severity varies enormously from one woman to another. If the symptoms are truly disabling, it may be best to take effective hormone treatment, in spite of the low risk of serious side effects. However, other drugs, such as clonidine or one of the SSRIs, may provide relief, with only annoying, but not serious, side effects.

Source

Hot flushes. V. Stearns, L. Ullmer, JF. Lopez,  et al., Lancet, 2002, pp. 1851--1861

Links

• Hormone Replacement Therapy (HRT) - Now What to Do?
• Menopause and Depression: Myth versus Reality
• Treating Hot Flashes - Without Hormones