Impact of 5-alpha reductase inhibitors on male reproductive health: A review of finasteride and dutasteride.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing clinical studies and animal mechanistic research.
PubMed 42069234 · doi:10.1016/j.reprotox.2026.109257
What was done
This narrative review synthesized published clinical and experimental literature, including randomized controlled trials, observational studies, and mechanistic investigations in rodents, evaluating the reproductive effects of 5-alpha reductase inhibitors (finasteride and dutasteride). Key evaluated outcomes were sperm parameters, hormonal profiles, sexual function, and potential long-term reproductive effects.
What was found
Finasteride and dutasteride were associated with reductions in sperm count (34% with finasteride, 29% with dutasteride), concentration, and motility. Hormonal findings included increased testosterone and variable changes in dihydrotestosterone, estradiol, progesterone, and androstenedione. Reported sexual dysfunction was variable, with some studies demonstrating persistent decreases in libido, erectile dysfunction, and reduced penile sensitivity months to years after discontinuation. Rodent studies showed decreased expression of spermatogenesis genes (Dazl, Prm2, Sycp3, Tsga10) and alterations in penile tissue contractility and nitric oxide synthase signaling.
Why it matters
This paper consolidates both clinical and preclinical evidence regarding potential adverse reproductive effects of 5-alpha reductase inhibitors used for androgenic alopecia, highlighting risks of semen impairment and post-discontinuation sexual dysfunction.
Limits
The abstract describes a narrative review rather than a systematic review or meta-analysis; total sample sizes and study counts are not reported. Findings on sexual dysfunction were noted to be variable, and molecular mechanisms rely primarily on rodent models.
Cited by
- context Inhibiting the 5-alpha reductase enzyme results in a proportional increase of 15% to 20% in intra-tissue estradiol.