Applied Evidence

Treating hot flushes without hormone replacement therapy

Machelle M. Seibel, MD
University of Massachusetts School of Medicine, Worcester


Practice recommendations

  • Ask your patients about complementary and alternative therapies; 21% of women say they use complementary or alternative therapies only, and another 25% say they use both conventional and alternative methods.
  • Women who take 50 mg of soy isoflavones daily report a 10% to 20% absolute risk reduction (number needed to treat, 5–10) in the frequency of hot flashes. The duration of this effect is unknown.
  • Black cohosh yields up to an 80% improvement in hot flashes.
  • Patients should use an alternative therapy for at least 1 month and keep a symptom diary to adequately assess its effect.

Physicians may recommend alternative treatments for hot flashes with the same confidence they have in prescription drugs if they understand the expected results, risks and benefits, and interactions with other medications.

For treatment of hot flashes, an increasing number of menopausal women are choosing plantbased alternatives to hormone replacement therapy (HRT). Despite HRT’s proven efficacy in treating this plaguing symptom, many patients are fearful that HRT might lead to an increased risk of breast or uterine cancer, increase the risk of vascular disease including heart attack, or cause unpleasant side effects such as mood swings, depression, or continued menstrual periods.1


Dr. Seibel, an expert in non-hormone replacement therapy and a proponent of soy, provides his view of options in this important area. He argues that treatment with the more promising soy and black cohosh preparations is worth considering as part of a careful “N of 1” trial. Read this issue’s Clinical Inquiry, “What nonhormonal therapies are effective for postmenopausal vasomotor symptoms?” (pages 324–329), and you be the judge. —Jeffrey L. Susman, MD

One study of 2500 postmenopausal women found that 20% to 30% never fill their initial HRT prescriptions, 10% of those who use estrogen do so only intermittently, an additional 20% discontinue their therapy within 8 months, and only 15% to 20% of women will take HRT for more than a year.2

HRT is contraindicated in about 10% of postmenopausal women3 ; the Womens’ Health Initiative4 and the Heart and Estrogen/progestin Replacement Study5 (HERS) trials have suggested caution in using HRT even for those without contraindications.

With such an enormous number of women either unwilling or unable to take HRT, it is important to consider the alternatives you can offer.6,7 (See “How pervasive are alternative therapies?”) Whichever alternative treatment you and a patient select, give it at least 1 month (and preferably 3 months) to assess its effectiveness. Keeping a symptom diary will allow patients to objectively track their progress.

How pervasive are alternative therapies?

So-called alternative approaches to menopause are used so widely it might be more accurate to consider hormone replacement therapy as the true alternative medicine. Statistics presented at the National Institutes of Health on October 27, 2000, indicate that nearly half of all menopausal women are using complementary therapies—including vitamins, herbs, and soy products—to help treat their symptoms. Twenty-one percent of the women surveyed used complementary or alternative therapies alone, and 25% said they used both conventional and alternative methods.

Taken together, that is more than twice the 19% who said they used conventional hormone replacement therapy only. Given this enormous usage, it should come as no surprise that, in 2001, the dietary supplement industry likely exceeded $12 billion in sales in the United States alone.4 For many women, the decision to use an alternative is not so much dissatisfaction with conventional treatment, but that they regard the complementary agents as more congruent with their own values, beliefs, and philosophical orientations toward health and life.5


Much of the excitement about the health benefits of soy—a staple of the Asian diet for 5000 years—stems from epidemiological studies. The Asian diet, which is rich in isoflavones, is associated with a reduced risk of breast cancer, heart disease, and osteoporosis. Asian women also report fewer hot flashes than do their Western counterparts.8 One study showed that women in Western countries have an 80% incidence of hot flashes, while Asian women living in China have an incidence of only 20%.9

Clearly, factors other than soy also must be considered before we can make a direct cause-and-effect correlation. To that end, many studies have been conducted on the health benefits of soybeans, a rich source of the isoflavones genistein and daidzein.

Physiologic activity

Isoflavones are phytoestrogens with a hetero-cyclic phenol structure that is similar to estrogen. Their potency is between 1 x 104 and 1 x 103 the activity of 17Β-estradiol.10 Although their potency is low, their serum concentrations can reach levels several orders of magnitude higher than those of physiologic estrogens. It is generally believed that isoflavones act as a selective estrogen receptor modulator, exerting antiestrogenic effects in the high-estrogen environment of premenopause and estrogenic effects in the low-estrogen environment of post-menopause.