Conclusions: Persistent adverse effects of finasteride in younger men include erectile dysfunction, low libido, lack of orgasms, depression, and decreased alcohol consumption. One study has found lower levels of several neurosteroids in this population. Out of the various persistent side effects, erectile dysfunction and decreased alcohol consumption have been the most studied in animal models. Further research is needed on who is susceptible to the persistent adverse side effects of finasteride and on the underlying mechanisms of the medication.
Irwig, MS. Persistent Sexual and Nonsexual Adverse Effects of Finasteride in Younger Men. Sex Med Rev. 2014 Jan;2(1):24-35. doi: 10.1002/smrj.19. Epub 2015 Oct 19. [PubMed]