The Food and Drug Administration added new warnings to Merck's baldness drug Propecia, known generically as finasteride, and sold as Proscar to treat an enlarged prostate, citing sexual side effects.
CBS News reports Propecia will now include warnings for libido disorders, ejaculation disorders, and orgasm disorders that continued for men even months after stopping the drug.
Proscar's label will have a warning for "decreased libido" and possible male infertility and poor semen quality that improved after patients discontinue the drug.
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The FDA released a statement saying "despite the fact that clear causal links between finasteride (Propecia and Proscar) and sexual adverse events have not been established, the cases suggest a broader range of adverse effects than previously reported in patients taking these drugs."
TIME writes the new labeling comes in response to the FDA's latest clinical trial results in studies from 1998 to 2011, in which users mention sexual dysfunction.
Out of 421 cases, 59 men reported adverse sexual effects that lasted longer than three months after drug discontinuation. The agency also reviewed 251 cases associated with semen quality; 13 had enough information for evaluation. For Proscar, the FDA reviewed 131 cases of erectile dysfunction and 68 cases of decreased libido from 1992 to 2010.
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