We use essential cookies (authentication, your saved goals/stack) by default. With your permission we'll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Mes3.6
Mesterolone (Proviron) Research
Mostly mechanism / observationalLimited safety
6 peer-reviewed studies
What the evidence says
Mostly mechanism / observational
Most Mesterolone (Proviron) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality meta-analyses and randomised trials published 1983–2012 with a typical study size of 52 participants.
Based on 6 studies · 1 meta-analysis · 3 RCTs · 346 total participants
Confidence
Moderate
By outcome
Hormones & male vitality
Mostly mechanism / observational4 studies
Fertility (largely negative)
Mostly mechanism / observational4 studies
Safety profile
Too few graded studies1 study
Older research base
Newest study from 2012 · Latest meta-analysis: 2007
198319972012
1Meta-Analysis2007
There is not enough evidence to evaluate the use of androgens for male subfertility.
Vandekerckhove P, Lilford R, Vail A, Hughes E. · Cochrane Database Syst Rev (2007)
Cochrane systematic review of randomized trials of androgens — including mesterolone — vs placebo or no treatment for idiopathic oligo/asthenospermia
Eleven trials, 930 patients; for stimulatory androgen therapy (mesterolone, testosterone undecanoate) androgens had little effect on endocrine outcomes and sperm parameters
Pregnancy rate after stimulatory androgens vs placebo/no treatment was similar — odds ratio 1.10 (95% CI 0.75-1.61), crossing 1.0
There were no significant changes [in] semen quality during the course of the study... [pregnancy-rate] ratios compared to placebo were 1.3 (0.5-3.2) and 1.8 (0.7-4.4) for the 75 and 150 mg mesterolone groups respectively.
World Health Organization Task Force on the Diagnosis and Treatment of Infertility. · Int J Androl (1989)
Prospective randomized double-blind multicentre trial (7 centres, 248 infertile couples) of 75 or 150 mg/day mesterolone vs placebo for 6 months in idiopathic male infertility
Cumulative pregnancy-rate ratios vs placebo (1.3 and 1.8) had confidence intervals crossing 1.0 — no statistically significant fertility benefit
No significant change in semen quality attributable to mesterolone; an early sperm-concentration rise was actually greatest in the placebo group
3RCTn=52 · small study1991
The overall pregnancy rate was similar in the Mesterolone-treated cases (26%) and in the placebo control cases (48%)... our findings cast doubt on the possible usefulness of high-dose Mesterolone treatment of idiopathic male infertility.
Treatment with the placebo, mesterolone, pentoxifylline, and testosterone rebound therapy did not result in a significant increase in the mean sperm concentration or pregnancy in the partners.
Wang C, Chan CW, Wong KK, Yeung KK. · Fertil Steril (1983)
Randomized comparison of placebo, clomiphene, mesterolone (100 mg/day), pentoxifylline, and testosterone rebound therapy in 46 men with idiopathic oligospermia
Mesterolone — like placebo — did NOT significantly increase mean sperm concentration or partner pregnancy
Only clomiphene significantly raised sperm concentration, illustrating that mesterolone's stimulatory rationale did not pan out
1 alpha-Methyl-5 alpha-dihydrotestosterone (1 alpha-methyl-DHT; mesterolone) bound most avidly to sex hormone-binding globulin (SHBG) [relative binding affinity about 4 times that of DHT].
Saartok T, Dahlberg E, Gustafsson JA. · Endocrinology (1984)
Receptor-binding study comparing anabolic-androgenic steroids' affinity for the androgen receptor in muscle and prostate and for SHBG
Mesterolone (1α-methyl-DHT) bound SHBG about four times more avidly than DHT — the mechanistic basis for its SHBG-displacement / free-testosterone effect
Its androgen-receptor binding in muscle and prostate was relatively weak (below testosterone), consistent with it being a weak anabolic
In the presence of increased estrogen production symptoms... a short-term trial with non-aromatizable androgens (dihydrotestosterone mesterolone or oxandrolone) could be advisable. However, after a few months of therapy, switching to other aromatizable preparations is recommended, to prevent bone loss.