Background Finasteride is commonly utilized in clinical practice for treating androgenetic alopecia, but real-world data regarding the long-term safety of its adverse events remains incomplete, necessitating ongoing supplementation. This study aims to evaluate the adverse events (AEs) associated with finasteride use, based on data from the US Food and Drug Administration Adverse Event Reporting System (FAERS), to contribute to its safety assessment. Methods We reviewed adverse event reports associated with finasteride from the FAERS database, covering the period from the first quarter of 2004 to the first quarter of 2024. We assessed the safety of finasteride medication and AEs using four proportional disproportionality analyses: reported odds ratio, proportionate reporting ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPN), and Multi-Item Gamma Poisson Shrinkage (MGPS). These methods were used to evaluate the of finasteride medication and AEs. whether there is a significant association between finasteride drug use and AEs. To investigate potential safety issues related to drug use, we further analyzed the similarities and differences in the onset time and AEs by gender, as well as the similarities and differences in AEs by age. Results Among the 11,557 adverse event reports where finasteride was the primary suspected drug, most patients affected were male (86.04%), with a significant proportion being the young adult aged 18-45 years (27.22%). We categorized 73 adverse events (AEs) into 7 different system organ categories (SOCs), which included common AEs like erectile dysfunction and sexual dysfunction. Notably, Peyronie's disease and post 5α reductase inhibitor syndrome were AEs not listed in the drug insert. We identified 102 AEs for men and 7 for women. Depression and anxiety were notable AEs for both male and female. Additionally, we examined 17 adverse events (AEs) in patients under 18 years old, 157 in patients aged 18 to 65 years, and 133 in patients aged 65 years and older. Each age group exhibited unique AEs, although erectile dysfunction, decreased libido, depression, suicidal ideation, psychotic disorder, and attention disturbance were common AEs observed across different age brackets. Ultimately, the median onset time for all instances was 61 days. The onset was mainly within one month after initiation of finasteride and it is noteworthy that the second highest number of cases involved adverse drug reactions persisted beyond one year of treatment. Conclusion The results of our study uncovered both known and novel AEs associated with finasteride medication. Some of these AEs were identical to the specification, and some of them signaled AEs that were not demonstrated in the specification. In addition, some AEs showed variations based on gender and age in our study. Consequently, our findings offer valuable insights for future research on the safety of finasteride medication and are anticipated to enhance its safe use in clinical practice.
