If you are pregnant, or planning to get pregnant, our medical advisers warn you to steer clear of the drug dutasteride (Avodart and generic) since it can cause birth defects, and the risks can continue for several months after you've stopped taking it. (Pregnant women don't even have to take it to be exposed to the risks—just handling the drug may cause abnormalities in male fetuses.) If pregnancy is not a concern for you, Avodart is still not a good first choice because there's little evidence showing that Avodart is effective in treating female pattern hair loss (FPHL).
Approved to treat enlarged prostate in men, and often prescribed as an "off label" treatment for male and sometimes female pattern baldness, Avodart is a type of drug known as a "hormone inhibitor" that works by blocking type I and type II of the enzyme 5a reductase, which converts testosterone to dihydrotestosterone—a hormone that contributes to hair loss in men, and to prostate enlargement. It also reduces dihydrotestosterone levels in the scalp, which slows hair loss and increases hair growth.
While Avodart showed some promise in effectively treating male pattern baldness in two large trials, there were side effects: sexual problems, including decreased libido and erectile dysfunction. Other side effects have been reported in association with Avodart, including depression, male breast enlargement, and skin reactions. But given the many causes and contributing factors that bring about hair loss in women—for example, a diet lacking in protein, certain medications, including antidepressants and blood thinners, low estrogen, and even some potentially damaging hairstyles—combined with the limited evidence from clinical trials for Avodart's use in women, it's difficult to predict how well or not it would work.
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That said, studies in and out of the U.S. that have looked at Avodart to treat hair loss in women, alone or in combination with other medications, including the similar drug finasteride (Propecia), an FDA-approved treatment for hair loss in men, have yielded some positive results. But most of those studies were small, and long-term safety and effectiveness for women remains unclear.
In the U.S., minoxidil 2 percent (Rogaine and generic) remains the only FDA-approved treatment for female pattern hair loss. "Topical minoxidil is the gold standard treatment for women," said Paradi Mirmirani, MD, a dermatologist with the Permanente Medical Group in Vallejo, Calif., and adjunct professor at the University of California-San Francisco School of Medicine.
If you're a woman with thinning hair or significant hair loss, talk with your doctor about referring you to a specialist to look for underlying causes, such as iron deficiency, lupus, skin disorders, and hormonal conditions, including thyroid disease. If other conditions are ruled out, the specialist may suggest treatment with minoxidil. Experts recommend using 2 or 5 percent minoxidil products for 12 months before judging its effectiveness, although benefits may appear sooner. Note that evidence also shows that once the minoxidil is stopped, all those new hairs (and there aren't all that many really) fall out within 3 to 4 months.
These materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multi-state settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).