Study Compares Safety Findings of Oral Versus Topical Finasteride for Alopecia

Both topical and oral finasteride are effective treatments for androgenetic alopecia (AGA), recent findings suggest, given that adverse events (AEs) that have been associated with their use can be attributed to confounding variables.1

Common AEs linked to finasteride use, many of which have been labeled as 'post-finasteride syndrome (PFS),' are persistent sexual and neuropsychiatric AEs following finasteride cessation. Contributing risk factors, however, had largely not been causally connected to the treatment's use.2

Aditya K. Gupta, MD, PhD—of Mediprobe Research Inc. in London, Ontario—led a team of trial investigators in a recent analysis of oral versus topical finasteride.

“This study uses FDA Adverse Event Reporting System (FAERS) data to compare PFS-like AEs between topical and oral finasteride and dutasteride, emphasizing that many reported AEs are non-specific and may reflect background rates or confounding factors rather than drug-specific effects,” Gupta and colleagues wrote.1

Design and Major Findings

The investigative team looked at data drawn from FAERS, seeking to identify potential safety signals associated with 13 AEs that had been associated with PFS. These AEs including erectile dysfunction, diminished libido, and suicidal ideation among users.

Using the information component (IC) approach, a form of disproportionality analysis, Gupta et al assessed both topical and oral forms of finasteride as well as dutasteride. The team's analyses were carried out across 2 distinct timeframes: 2006 - 2011 (prior to PFS being widely-reported) and 2019 - 2024 (following greater public awareness of PFS in the years following 2012). The investigators conducted 8 separate evaluations for each of the 13 adverse events, basing them on drug type, administration method, and timeframe.

The FAERS database, published quarterly since 1969, contains a set of 7 datasets: ‘DEMO’, ‘DRUG’, ‘INDI’, ‘OUTC’, ‘REAC’, ‘RPSR’, and ‘THER’. For the purposes of this analysis, only the ‘DEMO’, ‘DRUG’, and ‘REAC’ datasets were implemented by Gupta and colleagues. After data cleaning and deduplication, IC-based case/non-case disproportionality analyses were done for each AE analyzed by the investigative team.

Overall, the team concluded that topical finasteride generated fewer signals related to PFS-like events compared to its oral counterpart in both of the timeframes assessed.1 In contrast, topical dutasteride had a complete lack of AE signals, a result likely due to limited implementation of the treatment. A signal for erectile dysfunction emerged consistently across both forms of finasteride and during both timeframes analyzed in the analysis.

Among all the AEs examined, the investigative team found that erectile dysfunction accounted for the highest proportion of reported cases regardless of the drug or administration route of the treatment. Notably, the team highlighted that the commonly-reported AEs, such as erectile dysfunction and depressive symptoms, can be strongly influenced by confounders such as age, psychological stress, or underlying health conditions.

In their analysis, Gupta and coauthors suggested that the topical formulation of finasteride may carry a lower risk of PFS-related events, pointing to the drug's reduced systemic absorption. The complete absence of signals for topical dutasteride further supports this hypothesis, although its limited use prevents firm conclusions. Although finasteride is widely used, sexual and neuropsychiatric symptoms are common in the general population, but their presence in FAERS data may not necessarily imply causality.

These patterns, the investigators added, may be attributed to reporting bias—amplified by the nocebo effect and increased attention to PFS following 2012. Given the currently-available data, Gupta and colleagues noted that finasteride continues to be an effective option for androgenetic alopecia. Nonetheless, further clinical research may be warranted to clarify potential risks.

“Overall, finasteride remains an effective treatment for AGA-related hair loss,” the investigative team concluded.1 “Healthcare providers should inform patients about potential AEs and clarify that some symptoms often attributed to PFS are common in individuals not using finasteride.”

References

1. AK Gupta, M Talukder, MA Bamimore, et al. “Is the Safety of Finasteride Correlated With Its Route of Administration: Topical Versus Oral? A Pharmacovigilance Study With Data From the United States Food and Drug Administration Adverse Event Reporting System,” International Journal of Dermatology (2025): 1–11, https://doi.org/10.1111/ijd.17957.

2. H RS and DS Bin. “The Role of Topical Finasteride in Hair Loss Management: Current Evidence and Future Perspectives,” International Journal of Biomedicine 13, no. 4 (2023): 236–239.