An evaluation of the federal adverse events reporting system data on adverse effects of 5-alpha reductase inhibitors

World J Urol. 2021 Apr;39(4):1233-1239. doi: 10.1007/s00345-020-03314-9. Epub 2020 Jun 28.


Objective: To investigate the sexual, physical, and mental adverse effects associated with exposure to 5-alpha reductase inhibitors (5ARIs).

Methods: FAERS data containing finasteride and dutasteride reports were analyzed from January 2000 to April 2019. Reports identified one or more adverse effects, along with all concurrent medications. Cases of monotherapy of finasteride or dutasteride were identified. We conducted a chi-square test of independence to assess the relationship between the three drug groups and adverse event (AE) occurrence across 19 sexual, physical, and mental AE categories. The frequency procedure in SAS was utilized to summarize rates of AEs between various dosages of each drug.

Results: A total of 16,014 case reports were obtained. After excluding females, 7436 case reports of 5ARI monotherapy were identified: 2628 of dutasteride 0.5 mg, 3266 of finasteride 1 mg, and 744 of finasteride 5 mg. Differences in rates of AEs occurrence were statistically significant across all 19 variables (p < 0.001) with a significantly higher proportion of AEs attributed to finasteride 1 mg, with gynecomastia being the only exception. Case report submissions rose dramatically following FDA-mandated finasteride label change.

Conclusions: Analysis of FAERS data suggests AEs of 5ARIs are dose-independent with greater likelihood of occurrence in younger patients, particularly in sexual and mental domains. The causality and the rate of AEs are not certain based on the FAERS data and future prospective studies are necessary to determine the true rates.

Keywords: Androgenic alopecia; Benign-prostatic hyperplasia; Dutasteride; Finasteride; Post-finasteride syndrome.