Mesterolone
Proviron; oral DHT-derivative (1-methyl-DHT)
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Not US-approved; marketed abroad for androgen deficiency/some male infertility contexts; Schedule III in US
- WADA
- Prohibited at all times (S1 Anabolic Agents).
Reference only. Not medical advice.
This is something to take to a clinician. The Atlas can tell you what is known about mesterolone in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Mesterolone (Proviron) is an orally active dihydrotestosterone (DHT) derivative (1-methyl-DHT) marketed in many countries, though not FDA-approved in the US, for androgen deficiency and as an adjunct in some male infertility and libido contexts. Notably it is not 17-alpha-alkylated (it is 1-methylated), so it is comparatively less hepatotoxic than typical orals. It is a weak anabolic; in physique use it is taken mainly for its anti-estrogenic action and its ability to lower SHBG, thereby raising the free fraction of other androgens, not for muscle building per se.
An oral DHT-derivative used more as an SHBG and estrogen tool than for muscle.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
- Androgen deficiency (foreign)
- Marketed in some countries for symptoms of androgen deficiency.
- Male infertility/libido adjunct (foreign)
- Used in some settings as an adjunct, though evidence for fertility benefit is limited and contested.
How it is supposed to work
Mesterolone binds the androgen receptor and, as a DHT-derivative, does not aromatize. By occupying SHBG and exerting anti-estrogenic effects, it raises the free (active) fraction of co-circulating androgens and can blunt estrogenic side effects, the basis of its 'support' role rather than direct muscle growth.
A 5-alpha-DHT skeleton with a 1-methyl group (and 1,2-saturated A-ring). The 1-methylation (not 17aa) is why it is orally usable with comparatively lower liver burden.
Why SHBG matters
Sex hormone-binding globulin sequesters circulating androgens; by lowering SHBG, mesterolone increases free androgen levels. This is the mechanistic rationale users cite, but it also means it can intensify the androgenic and cardiovascular burden of a regimen rather than reduce overall risk. As a potent DHT-derivative it still drives hair loss and prostate effects.
Safety in detail
This intervention involves significant physiological effects and requires evaluation and monitoring by a qualified physician. Self-administration without medical oversight carries documented health risks.
- Potent DHT-derivative: male-pattern hair loss, acne, prostate stimulation.
- Lowering SHBG can amplify free-androgen exposure and androgenic risk.
- HPTA suppression (often underestimated for a 'support' drug).
- Adverse lipid effects; virilization risk in women.
- Not US-approved; illicit supply with counterfeit risk.
Replacement is not the same as a cycle
Foreign therapeutic dosing is supervised; physique 'support' use is unsanctioned and can intensify a supraphysiological regimen's androgenic load via SHBG reduction. No dosing guidance is provided here.
What it does to fertility
Despite historical 'fertility' marketing, exogenous mesterolone suppresses gonadotropins and can impair spermatogenesis; it should not be assumed to support fertility.
What has to be monitored
The bloodwork this needs, and the reason it belongs with a clinician rather than a website.
- Lipid panel
- PSA/prostate assessment
- LH/FSH, testosterone
- Hematocrit
- Blood pressure
What people get wrong
Often said'Proviron boosts fertility'
ActuallyBecause it suppresses gonadotropins like other exogenous androgens, mesterolone can worsen, not improve, spermatogenesis; its historical fertility use is contested and not a reliable benefit.
Often said'It is a harmless support drug'
ActuallyIt is a potent non-aromatizing DHT-derivative: hair loss, prostate stimulation and lipid effects apply, and lowering SHBG can amplify a regimen's androgenic load.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
How we got here
Mesterolone was introduced by Schering in the 1960s as Proviron for androgen deficiency and certain male reproductive complaints. It never gained US FDA approval. In physique culture it became valued less as an anabolic than as an oral anti-estrogen and SHBG-lowering adjunct.
- 1960sMesterolone (Proviron) introduced by Schering
- 20th c.Marketed abroad for androgen deficiency/infertility adjunct
- PresentNot US-approved; used illicitly as a 'support' compound
At a glance
- Class
- Oral DHT-derivative (1-methyl-DHT, non-17aa)
- Aromatization
- None
- Key context
- SHBG reduction; anti-estrogenic
- US status
- Not FDA-approved
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Mesterolone. A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- What can go wrong. We have not written the risk line for this one. Read the safety section below rather than treating its absence as reassurance.
- Where we land. We have not taken a position on this yet.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Foreign registration/clinical literature on mesterolone20th c.
Supports androgen-deficiency labeling; fertility benefit remains limited/contested.
SHBG pharmacology reviewsvarious
Establish SHBG's role in modulating free androgen availability, the basis of mesterolone's 'support' use.