Hair Loss Remedy Linked to Loss of Libido

Assistant Professor Michael S. Irwig, M.D., uncovers serious problems with Propecia
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According to the American Academy of Dermatology, roughly 50 million men and as many as 30 million women in the United States experience some form of hereditary hair loss. And by most accounts, Americans spend more than $1 billion each year on shampoos, potions, pills, toupees, and transplants to ward off the effects of hair loss. But how much is too much to pay for a full head of hair?

A new study by Michael S. Irwig, M.D., and assistant professor of Medicine in the Division of Endocrinology at GW’s School of Medicine and Health Sciences, who is also director of the Center for Andrology, suggests that men who take the hair loss drug finasteride — marketed by Merck under the trademark Propecia — may be paying a much steeper price than they expected. In the study, published in the Journal of Sexual Medicine, Irwig reveals that otherwise healthy men taking finasteride may experience ongoing sexual side effects well after they stop using the medication.

That news has attracted global attention; Irwig and his study have been widely featured in print, broadcast, and online media, including,, and la Folha, one of Brazil’s largest newspapers. The story was featured on CBS television stations in Chicago, New York, and Philadelphia, as well as on CBS Radio.

Finasteride inhibits the enzyme that converts testosterone to dihydrotestosterone, the male hormone associated with virilization and male pattern baldness. The drug was initially approved by the U.S. Food and Drug Administration (FDA) in 1992, under the brand name Proscar, as treatment for an enlarged prostate. Five years later, the FDA approved finasteride under the name Propecia to treat male pattern baldness.

An endocrinologist by training, Irwig launched the study after seeing several patients who reported persistent sexual side effects despite having stopped taking finasteride. He then found a website featuring posts about persistent sexual and other problems that adversely affect quality of life, with entries from more than 1,400 men.

Irwig studied a pool of 71 healthy men ages 21 to 46, who did not report any psychological issues such as anxiety or depression before starting finasteride. A staggering 94 percent of the men said they developed low sexual desire, 92 percent said they developed decreased arousal, 92 percent reported developing erectile dysfunction, and 69 percent said they developed problems with orgasm. Most patients used finasteride for an average of 28 months, but sexual side effects lasted for an average of 40 months after use was discontinued. 

In the study, said Irwig, “we sought to characterize the types and duration of persistent sexual side effects in otherwise healthy men who took finasteride.” He added that prior to his research, nobody had really described this effect. “While finasteride has been associated with reversible adverse sexual side effects in multiple randomized placebo-controlled trials, this is the first series to find that symptoms persisted for at least three months despite stopping finasteride.”

Although all the patients experienced the side effects for at least three months after they stopped using finasteride, explained Irwig, “as many as 20 percent said problems persisted for up to five years.”

The exact incidence of persistent sexual dysfunction is unknown, according to Irwig, because there is no accurate count of the number of people who have been prescribed the drug. He recommends that men contemplating the use of finasteride, whether for baldness or an enlarged prostate, discuss the potential risk for persistent sexual side effects with their doctors.

“Many of the men said, ‘Had I known about this beforehand I might have chosen another option,’ ” said Irwig. “It underscores how important it is for physicians who are treating male pattern hair loss to discuss the potential risk of persistent sexual side effects with their patients.

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