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Prescription medication — not a dietary supplement
Mesterolone (Proviron)is a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
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
ModerateBy outcome
Mesterolone (Proviron) has an evidence score of 3.6/10 — emerging evidence based on 6 indexed studies, including 1 meta-analysis. An oral DHT-derived androgen (Proviron) — chemically 1α-methyl-dihydrotestosterone, non-aromatizable, that binds the androgen receptor weakly but binds sex-hormone-binding globulin (SHBG) very avidly. Marketed for male hypogonadism and idiopathic male infertility, and used off-label in bodybuilding for libido, 'hardening', and to free up bound testosterone by occupying SHBG. Honest appraisal: the fertility/infertility evidence is WEAK and largely NEGATIVE — a WHO multicentre RCT, a Belgian placebo-controlled trial, and a Cochrane review all FAILED to show a real pregnancy or sperm benefit over placebo — and it is a prescription androgen (an anabolic-androgenic steroid), not a dietary supplement, with DHT-mediated hair-loss/prostate and lipid concerns. Representative study: PMID 17636603.
Testosterone (TRT)
Mostly mechanism / observationalThe primary male androgen and an FDA-approved prescription drug for diagnosed male hypogonadism — and a Schedule III CONTROLLED SUBSTANCE. For men with genuinely low testosterone, randomized trials show real benefits: the Testosterone Trials (TTrials) improved sexual function, mood, anemia and bone density in older hypogonadal men, and the large TRAVERSE trial found TRT non-inferior to placebo for major cardiac events. But those benefits were modest and indication-specific, NOT a longevity or anti-aging result. It is prescription-only; non-medical, supraphysiologic, and 'anti-aging' use is illegal and carries serious harms — erythrocytosis, suppressed sperm production/fertility, cardiovascular and psychiatric risk. This is a harm-reduction reference, not a recommendation, and testosterone is NOT a dietary supplement.
Last reviewed June 2026 · evidence from 6 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Mesterolone (Proviron) — 1α-methyl-DHT, an oral DHT-derived androgen
An oral DHT-derived androgen (Proviron) — chemically 1α-methyl-dihydrotestosterone, non-aromatizable, that binds the androgen receptor weakly but binds sex-hormone-binding globulin (SHBG) very avidly. Marketed for male hypogonadism and idiopathic male infertility, and used off-label in bodybuilding for libido, 'hardening', and to free up bound testosterone by occupying SHBG. Honest appraisal: the fertility/infertility evidence is WEAK and largely NEGATIVE — a WHO multicentre RCT, a Belgian placebo-controlled trial, and a Cochrane review all FAILED to show a real pregnancy or sperm benefit over placebo — and it is a prescription androgen (an anabolic-androgenic steroid), not a dietary supplement, with DHT-mediated hair-loss/prostate and lipid concerns.
Mesterolone is a real, well-characterized oral DHT-derived androgen (non-aromatizable, binds SHBG ~4× more avidly than DHT, weakly anabolic), but its marketed indication — improving idiopathic male infertility — is contradicted by controlled evidence: a WHO multicentre RCT, a Belgian placebo-controlled trial, and the Cochrane review all failed to show a real pregnancy or sperm benefit over placebo. Its off-label bodybuilding uses (libido, 'hardening', SHBG binding) are poorly evidenced, and as a prescription anabolic-androgenic steroid it carries DHT-mediated hair-loss/prostate and lipid risks. The evidence base is old and thin. Hence a low score.
Mesterolone (brand name Proviron) is a synthetic oral androgen — chemically 1α-methyl-5α-dihydrotestosterone (1α-methyl-DHT), a derivative of dihydrotestosterone (DHT) rather than of testosterone.
The 1α-methyl group makes it orally active without the heavy liver toxicity of 17α-alkylated steroids, and because it is already 5α-reduced (a DHT analog) it is NON-AROMATIZABLE — it cannot be converted to estradiol.
Pharmacologically it is an unusual androgen: in receptor-binding studies it binds the androgen receptor in muscle and prostate relatively weakly (a weak anabolic), yet binds sex-hormone-binding globulin (SHBG) extremely avidly — about four times more strongly than DHT itself.
That SHBG affinity is the mechanistic basis for its main off-label rationale in the bodybuilding community: by occupying SHBG it can transiently raise the free (unbound) fraction of a person's own or co-administered testosterone, and its DHT-like signaling is credited anecdotally with libido and a 'hardening'/anti-estrogenic feel.
None of those bodybuilding uses are well evidenced in controlled trials. Mesterolone's licensed indications are male hypogonadism/androgen deficiency and, historically, idiopathic male infertility — and the infertility evidence is where the honest picture turns negative.
The premise was that a 'stimulatory' androgen given at a dose low enough not to suppress pituitary gonadotrophins might directly support spermatogenesis or sperm maturation in the epididymis. That premise largely failed in controlled testing.
A large WHO Task Force multicentre randomized double-blind trial of 75 or 150 mg/day mesterolone vs placebo in idiopathic male infertility found no significant difference in pregnancy rate or semen quality.
A Belgian double-blind placebo-controlled trial of high-dose (150 mg/day) mesterolone for 12 months actually saw a higher pregnancy rate in the placebo arm, with the authors concluding the data 'cast doubt' on its usefulness.
A randomized comparison against clomiphene found mesterolone (like placebo) did not significantly raise sperm concentration or pregnancies, while clomiphene did.
The Cochrane systematic review of androgens (including mesterolone) for idiopathic oligo/asthenospermia concluded there is not enough evidence to support their use, with pooled pregnancy odds ratios crossing 1.0. So the marketed fertility indication is, on the controlled evidence, weak-to-absent.
Some smaller and older studies report softer benefits — improved subjective potency/'aging male' symptom scores and lower-urinary-tract quality of life, and the predictable endocrine signature of an exogenous androgen (suppressed total testosterone, estradiol, and SHBG, with a rise in the free-testosterone fraction).
The safety side is the side of a real androgen: as a 5α-reduced DHT derivative it can drive androgenic effects (acne, oily skin, accelerated male-pattern hair loss, prostate stimulation), it can adversely shift lipids (lower HDL) like other oral AAS, in-vitro work groups it with anabolic steroids that disturb adrenal steroidogenesis (a proposed mineralocorticoid/cardiovascular concern), and at higher doses any androgen can suppress the hypothalamic-pituitary-testicular axis.
It is a prescription anabolic-androgenic steroid and a doping agent on the WADA list — not a dietary supplement, not a longevity drug.
The overall picture: a genuine, mechanistically-distinct androgen (non-aromatizable, SHBG-binding, weakly anabolic) whose headline marketed use — improving male fertility — is not supported by controlled trials, whose bodybuilding uses are poorly evidenced, and which carries the androgenic risks of its class.
This is a hormonal compound for harm-reduction information, not a recommendation.
Mesterolone is 1α-methyl-dihydrotestosterone — a DHT derivative that is already 5α-reduced, so it cannot aromatize to estradiol. It signals through the androgen receptor (DHT-like), but binds the receptor in muscle and prostate relatively weakly, making it a weak anabolic.
In binding studies mesterolone binds sex-hormone-binding globulin (SHBG) about four times more avidly than DHT. By occupying SHBG it can transiently raise the free (unbound) fraction of a person's own or co-administered testosterone — the mechanistic basis for its off-label 'free-T' / libido use.
Like any exogenous androgen, mesterolone lowers measured total testosterone, estradiol, and SHBG and can suppress pituitary gonadotrophins (LH/FSH) at higher doses — which is also why a low-dose 'stimulatory' fertility effect never reliably materialized in trials.
How Mesterolone (Proviron) works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Tap node to isolate • Pinch to zoom • Tap edge for research
Prescription androgen — no supplement dose applies. Historic clinical/label use was oral mesterolone 25-150 mg/day (e.g. 25 mg 2-3×/day for androgen deficiency; 75-150 mg/day in the infertility trials, where it failed to beat placebo). Off-label bodybuilding use is typically 25-100 mg/day. Any use should be clinician-directed; it is not a self-administered supplement.
Can be taken without food
| Form | Type |
|---|---|
| 💊Oral tablet (mesterolone / Proviron) — a prescription androgen | Recommended |
| 💊Testosterone replacement therapy (a true aromatizable androgen, with monitoring) | Alternative |
| 💊Clomiphene/enclomiphene (raise endogenous testosterone while preserving fertility — the fertility-sparing option mesterolone is not) | Alternative |
Mesterolone is a DHT derivative; unlike testosterone it cannot aromatize to estradiol, and unlike clomiphene/hCG it does not restore the gonadal axis or fertility.
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: An oral androgen historically taken in divided daily doses; clinician-directed, not a fixed supplement schedule.
Dose-response data unavailable. The current published research for Mesterolone (Proviron) does not provide sufficient dose-specific outcome data to generate reliable dose-response curves.
Refer to the Dosage & Timing section above for recommended dose ranges based on available evidence.
Older studies report improved subjective potency and 'aging male' symptom scores; DHT-like androgenic signaling plus SHBG occupancy plausibly raise libido, but controlled evidence is thin and mostly small/uncontrolled.
Despite being marketed for idiopathic male infertility, controlled trials (WHO multicentre RCT, Belgian placebo-controlled trial) and the Cochrane review found no real pregnancy or sperm benefit over placebo.
As a potent DHT derivative it can accelerate male-pattern hair loss, cause acne/oily skin, and stimulate the prostate; it can also worsen lipids (lower HDL) like other oral AAS.
Mesterolone is a prescription anabolic-androgenic steroid and a WADA-banned substance — not a dietary supplement and not a longevity drug; use is off-label and unsupervised in most bodybuilding contexts.
Do not rely on mesterolone — controlled trials (WHO RCT, Belgian placebo-controlled trial) and the Cochrane review found no real fertility benefit over placebo. Consider an evidence-based pathway with a reproductive specialist.
The libido/'hardening'/SHBG-binding uses are poorly evidenced; it is a prescription AAS and WADA-banned doping agent with androgenic and lipid risks. Harm-reduction: lowest effective dose, monitor lipids and prostate, avoid if hair-loss-prone.
Some small/older studies show symptom-score improvement, but it suppresses measured testosterone and SHBG and does not restore the gonadal axis; discuss properly monitored TRT alternatives with a clinician.
Not appropriate — a potent androgen with virilizing potential and effects on growth/development.
Stacking androgens (the common bodybuilding pattern) compounds androgenic load, lipid harm, and axis suppression; the SHBG-displacement 'free-T' rationale is not validated.
Androgens/anabolic steroids can potentiate warfarin and increase bleeding risk; monitor INR if combined.
Tip: DHT-mediated androgenic effects; not blocked by finasteride. Discontinue if scalp hair loss is a concern.
Tip: Androgens stimulate prostate tissue; screen prostate health and avoid with prostate cancer or significant BPH.
Tip: Like other oral AAS, can worsen the lipid profile; monitor lipids during use.
Tip: Any exogenous androgen can suppress LH/FSH and endogenous testosterone at higher doses; clinician monitoring required.
The commonly studied dose of Mesterolone (Proviron) is Prescription androgen — no supplement dose applies. Historic clinical/label use was oral mesterolone 25-150 mg/day (e.g. 25 mg 2-3×/day for androgen deficiency; 75-150 mg/day in the infertility trials, where it failed to beat placebo). Off-label bodybuilding use is typically 25-100 mg/day. Any use should be clinician-directed; it is not a self-administered supplement.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for Mesterolone (Proviron) — consistent daily use matters more than the time of day. An oral androgen taken in once- to thrice-daily divided doses; there is no validated supplement timing.
Mesterolone (Proviron) should be used with caution — talk to a healthcare provider before taking it. The most commonly reported side effects are accelerated male-pattern hair loss / acne / oily skin, prostate stimulation / lower-urinary-tract effects, adverse lipid changes (lower HDL). Use caution if any of these apply to you: Prostate cancer or untreated benign prostatic hyperplasia (androgens stimulate prostate tissue); Men attempting to conceive — it does not improve fertility and androgens can impair spermatogenesis; Pre-existing male-pattern hair loss that the user wants to avoid worsening.
Tamoxifen (Nolvadex)
Mostly mechanism / observationalA selective estrogen receptor modulator (SERM) and one of the most successful cancer drugs ever made: in estrogen-receptor-positive breast cancer, five years of adjuvant tamoxifen cuts 15-year recurrence by roughly half and breast-cancer death by about a third (EBCTCG), and it prevents breast cancer in high-risk women (NSABP P-1). Among men it is used OFF-LABEL — it antagonizes estrogen in breast tissue to prevent or treat gynecomastia (well-supported by RCTs during antiandrogen therapy, and in idiopathic/pubertal cases), and it blocks estrogen feedback at the hypothalamus to raise LH/FSH and endogenous testosterone, which is why it appears in male-infertility regimens and bodybuilding post-cycle therapy (PCT). The honest limits are real and non-negotiable: tamoxifen raises the risk of endometrial cancer and venous thromboembolism (clots, pulmonary embolism, stroke) and can cause visual/ocular changes. It is NOT a longevity drug.
Mesterolone is already a 5α-reduced DHT derivative, so 5α-reductase inhibitors will not blunt its androgenic (e.g. hair-loss) effects the way they do testosterone's.