Finasteride side effects: what 59,947 FDA adverse event reports show

Causality screen of the 40 strongest signals

Strongest disproportionality signals

Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only (and, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 1,169 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Trial evidence (ClinicalTrials.gov)

Most frequently reported reactions

By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.

Unlabeled candidate signals

These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.

• Right atrial hypertrophy — n=91, PRR 1,647.5
• Hair transplant — n=49, PRR 991.5
• Semen viscosity decreased — n=63, PRR 802.6
• Testicular failure — n=75, PRR 452.6
• Male genital atrophy — n=56, PRR 409.8
• Genital atrophy — n=72, PRR 358.9
• Epididymal cyst — n=49, PRR 271.9
• Painful ejaculation — n=95, PRR 249.4
• Penile size reduced — n=395, PRR 246.6
• Hypogonadism male — n=87, PRR 210.7

✓ A hand-written Bradford Hill causality assessment exists for this drug: Finasteride ↔ Sexual dysfunction.

Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.

Common questions

Sources & methods

• FDA label via openFDA (set ID 1c1bf77c-f99a-44e4-b71e-ce766afa99b6, effective 20201030; matched on openfda.generic_name.exact:"FINASTERIDE")
• Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
• FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA count= aggregation, field patient.drug.openfda.generic_name.exact, 1,209 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction
• Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
• Seriousness and sex counts from openFDA count=serious, patient.patientsex, seriousnessdeath
• ClinicalTrials.gov API v2 (query FINASTERIDE, results-bearing studies sorted by enrollment)

Page generated 2026-10-14. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.