Mesterolone
Also known as: proviron
The 'proviron' compound: a weak oral androgen used more as a supporting drug than as a muscle builder.
Legal status: UK: prescription-only medicine; legitimately available only via a doctor's prescription. Checked 2026-07-26.
Prohibited in sport: Yes — on the WADA Prohibited List.
Approved medical use: Licensed for androgen deficiency and for some cases of male infertility.
What it is
Mesterolone is an orally active DHT derivative. Unusually for an oral androgen it is not 17-alpha-alkylated, so it does not carry the same hepatic burden. It is a weak anabolic and is used in this context mainly for its ability to bind sex hormone binding globulin and for mild anti-oestrogenic activity.
It remains a licensed prescription medicine for androgen deficiency and certain fertility problems in men, prescribed and monitored by a doctor.
What’s claimed
- Increased free testosterone by displacing it from binding globulin
- Reduced oestrogenic effects from other compounds
- Improved libido and a harder appearance
What the evidence shows
The binding-globulin mechanism is real, and mesterolone does raise free testosterone, but the effect on muscle is small: it is not a building drug and is not sold as one even within the culture that uses it (Bronze). Its reputation for improving libido has some clinical basis in androgen-deficient men; extrapolating that to men with normal hormone levels is not supported.
The risks
- Androgenic: as a DHT derivative it accelerates male-pattern hair loss in those predisposed and has prostate effects.
- Lipids: marked lowering of HDL ('good') cholesterol and raising of LDL, an adverse cardiovascular shift that is more pronounced with oral compounds.
- Endocrine: it still suppresses the body's own production, contrary to a persistent belief that it does not.
- Androgenic: acne, male-pattern hair loss in those predisposed, and in women virilising effects, deepening of the voice, facial hair growth and clitoral enlargement, some of which do not reverse.
What needs monitoring
- Full blood count, including haematocrit and haemoglobin
- Lipid profile
- Blood pressure
- Liver and kidney markers
- Testosterone and the wider hormonal axis: a doctor is the right person to arrange these tests and to interpret what they show.
Sources
- NHS. Anabolic steroid misuse — health risks and the law.
- GOV.UK. Controlled drugs: Misuse of Drugs Act 1971 drug classes.
- World Anti-Doping Agency. The Prohibited List.
- Pope HG, et al. Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement. Endocr Rev. 2014;35(3):341-375.