A substantial body of evidence exists which points to serious and potentially ill-health effects of [finasteride and dutasteride] therapy. These include loss or reduced libido, erectile dysfunction, orgasmic and ejaculatory dysfunction, development of high-grade PCa tumors, potential negative cardiovascular events, and depression. The side effects are potentially harmful in some individuals and in young men may be persistent or irreversible. The argument that the benefits of these drugs outweigh the risks is slowly eroding in the face of new emerging scientific evidence from preclinical and clinical studies. The available data demonstrate that such drugs do pose serious adverse effects, especially in a subset of men who may have the predisposition to be affected severely. This is also corroborated by the overwhelming FDA disapproval of these drugs for the chemoprevention of PCa. The FDA mandated relabeling issued in 2011 equally points to the dark side of these drugs on human health. Physicians need to be aware of the adverse side effects of these drugs and are encouraged to share this information with their patients prior to commencing therapy with finasteride or dutasteride.
Traish MT, Mulgaonkar A, Giordano N, et al. The Dark Side of 5α-Reductase Inhibitors' Therapy: Sexual Dysfunction, High Gleason Grade Prostate Cancer and Depression. Korean J Urol. 2014 Jun; 55(6): 367–379. Published online 2014 Jun 16. doi: 10.4111/kju.2014.55.6.367. [PubMed]