Proscar, a drug used to shrink enlarged prostates, has been shown shrink some things that most men would prefer to be robust, like sex drive. The evidence is sufficiently persuasive that the Food and Drug Administration will now require the drug’s label to carry a warning of “libido disorders, ejaculation disorders, and orgasm disorders that continued after discontinuation of the drug.” The drug’s active chemical compound, finasteride, is also used in the baldness-treatment drug Propecia, which will be required to carry the same warning. The FDA website reports that the agency reviewed 421 postmarketing reports of sexual dysfunction submitted to the Agency’s Adverse Events Reporting System (AERS) database between 1998 and 2011. Of these, 59 cases reported sexual dysfunction that lasted for at least three months following discontinuation of Propecia, and included erectile dysfunction, decreased libido, problems with ejaculation and orgasm disorders. For Proscar, FDA reviewed 131 cases of erectile dysfunction and 68 cases of decreased libido associated with the use of finasteride 5 mg submitted to the drug sponsor’s worldwide safety database between 1992 and 2010. Where information was available, these reported events of erectile dysfunction and decreased libido lasted for at least several weeks after drug discontinuation. Read more from the FDA.