Recent news reports, coupled with warnings from Merck and the FDA, about Propecia’s possible persistent sexual side effects have caused growing concern about this popular hair loss treatment. An increasing number of men now fear that Propecia (finasteride 1mg) will cause permanent sexual dysfunction.
Merck’s and the FDA’s warning, however, was based on a small number of random self-reports, not on empirical studies that showed a cause and effect relationship between finasteride and sexual dysfunction. There are two possible reasons that existing studies have not found a significant relationship between finasteride use and persistent sexual dysfunction: 1) the effect of finasteride on sexual function is too small to significantly measure in any one study, or 2) finasteride has no significant negative effect on sexual function.
To address the first possibility, Aditya K Gupta and Andrew Charrette ((Gupta AK, Charrette A. The efficacy and safety of 5α-reductase inhibitors in androgenetic alopecia: a network meta-analysis and benefit-risk assessment of finasteride and dutasteride. J Dermatolog Treat. 2014;25(2):156-61.)) at the University of Toronto recently conducted a large scale meta-analysis across 16 controlled studies, studies designed to test the efficacy of finasteride, to see if a significant number of patients in those studies reported persistent sexual side effects. The rationale of a meta-analysis is that if there is an effect (of finasteride on sexual function) that is too small to measure in any one particular study, then it may be possible to detect the effect if one pools data from many different studies.
Gupta and Charrette analyzed the results of 16 studies that compared various doses of finasteride against a placebo and found that finasteride consistently proved effective in stopping or slowing hair loss. They also found that the number of self-reported cases of persistent sexual dysfunction by patients given finasteride was statistically no different from the number reported by patients given a placebo.
In other words, they found that finasteride was no more likely to cause persistent sexual dysfunction than a placebo.
This study supports the conclusion of existing literature that there is no correlation between finasteride use and persistent or permanent sexual dysfunction. That said, this is an important issue that still needs to be studied.
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The 21st Annual Scientific Meeting of the International Society of Hair Restoration Surgery was held in San Francisco from October 13 through 26, 2013. The meeting covers the most important scientific and clinical advances in the field of 
