Dutasteride

A 2026 systematic review of 41 studies on 5-alpha-reductase inhibitors in androgenetic/male- or female-pattern hair loss found sexual adverse events reported in 1.9-6.7% of men on oral finasteride 1 mg versus 0.9-3.9% on placebo, and in 4.1-12.0% of men on dutasteride 0.5 mg versus 4.0-5.0% on placebo, with most events described as mild and reversible after stopping treatment; no consistent sexual adverse effects were reported in women treated for hair loss.^[2]

• Abstract-checked; individual per-study data behind the 41-study synthesis were not independently re-verified in this batch.
• Reported ranges span multiple trials of differing design and duration in an androgenetic-alopecia population; they are not a single pooled point estimate and do not quantify risk in anabolic-androgenic-steroid users.
• "Mild and reversible" reflects reporting in the synthesized trials as characterized by this review's authors, not an independent adjudication in this dossier. No qualified clinical review.

A randomized study in 99 healthy men found dutasteride and finasteride suppressed serum DHT by 94% and 73% respectively, with transient decreases in some semen measures (largest at 26 weeks) that were no longer statistically significant by 52 weeks or after a 24-week drug-free follow-up. It did not establish guaranteed infertility, guaranteed full recovery for every person, or protection against other AAS harms.^[1]

• Corrected abstract inspected; the linked 2007 erratum text remains unresolved after a fresh, unsuccessful search (NCBI page-based search and Crossref bibliographic search). Exact numerical semen estimates are taken from the corrected abstract as displayed by PubMed, which itself carries an inline "[corrected]" marker on one figure.
• Abstract-checked; full paper not confirmed open access as of 2026-09-09. No qualified clinical review.

Laboratory experiments found reduced androgen-receptor affinity after nandrolone underwent 5-alpha reduction. The 1985 study tested neither finasteride nor dutasteride and did not establish human hair-loss or prostate outcomes; an interaction inferred from that study is mechanistic.^[3]

• Rat and cell experiments cannot quantify clinical benefit or harm for either named pair.