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



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


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.


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.


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.

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Author information




MBH: data collection/management/analysis, and manuscript writing. KH: data collection/management/analysis, and manuscript writing. AET: manuscript editing. SAK: manuscript editing. BC: protocol/project development, and manuscript writing/editing.

Corresponding author

Correspondence to Bilal Chughtai.

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The author(s) declare that they have no conflict of interest.

Research involving human participants

The data used in this study are de-identified and publicly available FAERS data. It has been determined by the Institutional Review Board (IRB) at Weill Cornell Medical College that it meets eligibility for IRB review exemption authorized by 45 CFR part 46.

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Harrell, M.B., Ho, K., Te, A.E. et al. An evaluation of the federal adverse events reporting system data on adverse effects of 5-alpha reductase inhibitors. World J Urol 39, 1233–1239 (2021).

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  • Post-finasteride syndrome
  • Finasteride
  • Dutasteride
  • Benign-prostatic hyperplasia
  • Androgenic alopecia