Background/Objectives: Finasteride and dutasteride are 5α-reductase inhibitors that block the conversion of testosterone to dihydrotestosterone, reducing androgenic stimulation of tissues such as the prostate and hair follicles. Used mainly for benign prostatic hyperplasia and androgenic alopecia, finasteride selectively inhibits type-2 5α-reductase isoenzyme, while dutasteride inhibits both type-1 and type-2. Although sexual adverse effects like erectile dysfunction are well-documented, emerging evidence suggests possible neuropsychiatric reactions—including depression, suicidal ideation, and cognitive decline—potentially linked to reduced neurosteroid synthesis, such as that of allopregnanolone. Causality cannot be inferred from spontaneous reporting data. This study aimed to assess pharmacovigilance signals for psychopathological disorders associated with finasteride and dutasteride in the FAERS database. Methods: Cleaned FAERS data referring to years up to 2025 after deduplication were analyzed, excluding non-serious cases and those without the drug as the sole suspect (MedDra 29.0). Reporting Odds Ratios (RORs) with 95% CIs were calculated to compare psychiatric reactions between finasteride and dutasteride. Python 3.11 was used to screen and summarize relevant cases, accounting for differences in total case numbers. Results: This pharmacovigilance study analyzed FAERS data to assess the neuropsychiatric and sexual adverse reactions associated with finasteride and dutasteride. Depression, anxiety, suicidality, and libido-related issues were reported more frequently for finasteride, especially in younger men using low-dose therapy for alopecia. Potential mechanisms include reduced neurosteroid synthesis, androgen/sex-hormone axis disruption, altered hippocampal neurogenesis, and dopaminergic changes. Conclusions: A baseline psychiatric assessment and the regular monitoring of mood, sexual function, and suicidal ideation are recommended. Limitations include under-reporting, reporting bias, and a lack of incidence data. The findings underscore the need for ongoing surveillance and controlled studies to clarify the clinical significance of these signals.
Chiappini et al. (Sat,) studied this question.