Introduction Recent studies have reported persistent sexual and nonsexual adverse effects associated with the 5α‐reductase inhibitor finasteride.

Aims The first aim was to review the clinical studies of persistent sexual and nonsexual adverse effects associated with finasteride in younger men who took the medication for treatment of male pattern hair loss. The second aim was to place these findings into context with what is known from basic and clinical studies about the hormones and neurosteroids affected by finasteride.

Methods Relevant published literature on the topic was reviewed. Clinical symptomatology in humans was correlated with findings from rodent models to investigate possible underlying mechanisms.

Main Outcome Measures Persistent sexual and nonsexual adverse effects were summarized.

Results Two clinical studies have described persistent side effects associated with finasteride use in otherwise healthy younger men. The sexual side effects are typically present in multiple domains that include erectile dysfunction, low libido, and decreased orgasms. Erectile dysfunction may be related to low levels of dihydrotestosterone, which has been shown to be an important androgen in both human and animal studies. Nonsexual side effects include depression and decreased alcohol consumption that are linked to the neurosteroid allopregnanolone in both human and animal studies. Three men with persistent side effects associated with finasteride were found to have lower plasma and cerebrospinal fluid levels of several neurosteroids.