July 18, 2012 — A new study of Propecia (finasteride) suggests that the hair loss drug’s “persistent” sexual side effects could last months or years, which raises concerns about permanent sexual dysfunction. The study was conducted by Dr. Michael Irwig of George Washington University, who published the data in the latest issue of Journal of Sexual Medicine. According to Dr. Irwig, “20% of subjects with male pattern hair loss reported persistent sexual dysfunction for ≥6 years, suggesting the possibility that the dysfunction may be permanent.”
To conduct the study, Dr. Irwig recruited 54 adult men from an online forum for men suffering from sexual side effects of Propecia. All of the men reported at least three months of sexual dysfunction that continued even after they discontinued Propecia. When a side effect lasts for at least three months, it is described as “persistent.” The label on Propecia has recently been updated to warn about the risk of persistent sexual dysfunction, including impotence, ejaculation disorders, orgasm disorders, and more.
Dr. Irwig wanted to get a better idea of how “persistent” these side effects really are. All of the men in the study were followed and monitored for an average of 14 months. All of the subjects were otherwise healthy before they started taking Propecia, and had no baseline sexual dysfunction or other disorders that could skew the results. At the end of the study, 96% of the subjects continued to report persistent sexual dysfunction. He also found that 89% met the Arizona Sexual Experience Scale (ASEX) definition for sexual dysfunction.
One notable drawback of this study is a sample bias, because all of the subjects were chosen from a pool of men who had suffered the persistent side effects of Propecia long enough to seek help on an online forum. Therefore, the percentages of dysfunction should not be extrapolated to the general population. In well-controlled clinical studies, around 2-3% of men who take Propecia have reported sexual side effects. However, until more studies are conducted, it is still unknown how often these side effects are persistent or permanent.