Medications that counteract excessive male hormones in women are mildly effective in reducing unwanted hair on the face and body, according to a new study being presented Sunday, June 3, at The Endocrine Society’s 89th Annual Meeting in Toronto.

However, the medications, called anti-androgens, do not appear to be effective in every woman, said lead author Dr. Brian Swiglo. “We estimate that two to six women need to be treated for more than six months for one woman to notice good improvement of hirsutism,” said Swiglo, a second-year endocrinology fellow and researcher with the Knowledge and Encounter Research Unit at the Mayo Clinic.

Hirsutism is the medical term for excessive hair growth in areas where hair is usually absent, and it affects 5 to 10 percent of women. The condition frequently is treated with anti-androgens, medications that lower androgens (male hormones). However, it has not been clear whether anti-androgens successfully treat hirsutism, because study results have varied widely, Swiglo said.

Therefore, Swiglo and co-workers performed a systematic review and meta-analysis—a statistical analysis and integration of results—from 12 studies of female hirsutism published through May 2006. The studies evaluated hirsutism in women treated at least six months with an anti-androgen, either alone or combined with another drug. Outcomes were an improved score on a commonly used scale for quantifying hirsutism in women.

They found that the anti-androgen drugs spironolactone, flutamide and finasteride reduced hirsutism scores more than did a placebo. Although finasteride can stimulate hair-growth in men, it can have the opposite effect in hirsute women, Swiglo said. Spironolactone and flutamide also were more effective than the insulin-sensitizing medication metformin, according to the pooled results.

Most of the published studies, however, were small, and only three studies asked women if they thought their hirsutism had improved. Swiglo said, “We need more research that can tell us if the women themselves notice an improvement, which is key to this cosmetic problem.”

He cautioned that anti-androgens can cause birth defects and thus should be used with oral contraceptives in women who may become pregnant. Their research showed that for women already taking the pill, adding an anti-androgen can further reduce hirsutism.

The Endocrine Society funded this study.

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