Recent studies of adverse events

A wave of studies of adverse event reports link finasteride to sexual disorders as well as cognitive dysfunction.

The field of pharmacovigilance assess the effects of drugs as they are used in the real world. Researchers often use adverse event (AE) data from FDA’s FAERS database or the World Health Organization’s EudraVigilance database. The records, which can be submitted by a health care provider or a patient, include AEs that a patient experienced along with demographic information.

A method called disproportionality analysis aims to distinguish the signal from the noise.

These reports come from many sources. Because some patients have multiple diagnoses and use multiple drugs, the connection between a drug and an adverse event can be ambiguous. A method called disproportionality analysis aims to distinguish the signal from the noise. A class of AEs for a drug of interest—say, memory loss with drug A—are compared with the same AEs in a group of other drugs—drugs B to J. This group provides a baseline level of adverse events, something like a control group. If drug A has a disproportionate share of certain AEs compared to the other drugs, this indicates an elevated risk associated with drug A. The result may be reported as a reporting odds ratio (ROR), which expresses how much more likely a report for drug A is. An ROR of 10 means it is 10x more likely to see a report for memory loss with drug A compared to B–J. Statistical results include a confidence interval and p-value which indicate the strength of the finding.

This post provides brief highlights of study results related to finasteride and in some cases dutasteride. The drug class is 5-alpha reductase inhibitors (5-ARIs).

Kaplan-Marans et al, 2022 on erectile dysfunction1

Among 20 medications with the highest frequency of erectile dysfunction reports in FDA’s FAERS database, 5-ARIs had the highest risk ratios. See Figure 2. Go to the study

Schifano et al, 2023 on penile curvature or Peyronie’s disease2

In a disproportionality analysis, finasteride had a proportional risk ratio of 11.8 (confidence interval: 9.08–15.33) for penile curvature or Peyronie’s disease, compared to nine other drugs. Go to the study

Fusaroli et al, 2023 on impaired communication3

This study analyzed adverse events associated with impaired communication such as aphasia and dysarthria. The analysis was limited to people with diagnoses of psychotic or affective disorders; however, the authors suggest that drug adverse effects could be a reason for misdiagnosis with these conditions. In the disproportionality analysis, finasteride had a risk odds ratio of 11.9 (confidence interval: 8.16–16.79) for adverse events related to communication. Go to the study

Baldini et al, 2023 on male-factor infertility4

Finasteride had the highest percentage of cases of male-factor infertility (MFI) of all drugs in the database. The proportional risk ratio of MFI associated with finasteride was 16.04 (confidence interval: 12.67–20.3), second only to a chemotherapy drug. Go to the study

Cho et al, 2023 on cognitive dysfunction5

From the abstract:

The study found a significant disproportionality for cognitive dysfunction related to finasteride use (rOR 5.43, 95% CI 5.17–5.71). Most cases were considered serious (65.83%), with no signs of recovery (58.37%). Sensitivity analyses showed that patients younger than 45 years (rOR 7.30, 95% CI 6.39–8.35) and those with alopecia (rOR 5.52, 95% CI 5.15–5.91) reported more cognitive dysfunctions than their counterparts.

Go to the study

Nacchia et al, 2024 on ejaculatory disorders6

In the FDA FAERS database, finasteride had the highest number of ejaculatory disorders. The most common disorders with finasteride were painful ejaculation and ejaculation failure. Go to the study

Tan et al, 2024 on reduced semen quality7

Among 40 common drugs that reduced semen quality, finasteride and dutasteride had the strongest signal of this type of adverse event. See Figure 3. Go to the study

Figure 5 from Tan et al, 2024. A bar chart which shows that finasteride and dutasteride have the strongest signals for reduced semen quality.

  1. Kaplan-Marans E, Sandozi A, Martinez M, Lee J, Schulman A, Khurgin J. Medications most commonly associated with erectile dysfunction: evaluation of the Food and Drug Administration national pharmacovigilance database. Sex Med. 2022. doi:10.1016/j.esxm.2022.100543 ↩︎
  2. Schifano N, Capogrosso P, Boeri L, et al. Are finasteride-related penile curvature/Peyronie’s disease adverse event reports worthy of further clinical investigation? Disproportionality analysis based on both the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) pharmacovigilance databases. Int J Impot Res. 2023. doi:10.1038/s41443-022-00568-2 ↩︎
  3. Fusaroli M, Simonsen A, Borrie SA, et al. Identifying medications underlying communication atypicalities in psychotic and affective disorders: a pharmacovigilance study within the FDA Adverse Event Reporting System. J Speech Lang Hear Res. 2023. doi:10.1044/2023_JSLHR-22-00739 ↩︎
  4. Baldini S, Khattak A, Capogrosso P, et al. The possible role of prescribing medications, including central nervous system drugs, in contributing to male-factor infertility (MFI): assessment of the Food and Drug Administration (FDA) pharmacovigilance database. Brain Sci. 2023. doi:10.3390/brainsci13121652 • PMC full text ↩︎
  5. Cho Y, Bea S, Bae JH, Kim DH, Lee JH, Shin JY. Cognitive dysfunction following finasteride use: a disproportionality analysis of the global pharmacovigilance database. Expert Opin Drug Saf. 2023. doi:10.1080/14740338.2023.2294926 ↩︎
  6. Nacchia A, Franco A, Cicione A, et al. Medications mostly associated with ejaculatory disorders: assessment of the EudraVigilance (EV) and Food and Drug Administration (FDA) pharmacovigilance databases entries. Urology. 2024. doi:10.1016/j.urology.2023.12.021 ↩︎
  7. Tan H, Luo L, Li W, et al. A pharmacovigilance study of drug-reduced male semen quality based on the Food and Drug Administration adverse event reporting system database. Andrology. 2024. doi:10.1111/andr.13668 ↩︎