In a group of 54 otherwise healthy former users of finasteride who developed persistent sexual side effects that lasted for at least 3 months, 96% continued to experience these effects when reassessed 9–16 months (mean 14 months) later, raising the possibility of permanent effects. To explain the long-term neurological effects of finasteride, it is possible that reduced concentrations of neuroactive steroids are affecting the plasticity of neuronal architecture in regions of the brain responsible for sexual function. The most volunteered changes related to the urogenital system in terms of semen quality and decreased ejaculate volume, reduction in penis size, penile curvature or reduced sensation, fewer spontaneous erections, decreased the testicular size, testicular pain, and prostatitis. Many subjects also noted changes to their mental abilities, sleeping patterns, and/or depressive symptoms. Many subjects reported a “disconnection” between the mental and physical aspects of sexual function. Further valuable research could determine who would be susceptible to finasteride through genetic studies of polymorphisms of 5a reductase and the androgen receptor. Further research with validated instruments is needed to study the nonsexual persistent side effects associated with finasteride.
Irwig, MS. Persistent sexual side effects of finasteride: could they be permanent? J Sex Med. 2012 Nov;9(11):2927-32. doi: 10.1111/j.1743-6109.2012.02846.x. Epub 2012 Jul 12. [PubMed]