Peptide & experimental
Mesterolone (Proviron)
Oral androgen, derivative of dihydrotestosterone (DHT) without 17α-alkylation; prescription-only medicine in several EU countries, currently not on the market in Germany · Proviron, Pro-Viron, Mesterolone, 1α-methyl-dihydrotestosterone, 1-methyl-DHT
Mesterolone is an androgen in tablet form, chemically a derivative of dihydrotestosterone. As Proviron, it is a prescription-only medicine for androgen deficiency in men in several European countries; in Germany, no product is currently on the market. Unlike most substances in this area, there are randomized trials – for the purposes tested, the results were sobering.
In short
Mesterolone is an approved medicine with a package leaflet, contraindications and decades of post-marketing surveillance, most recently updated in Belgium in 2024. In the 1970s and 1980s it was tested in double-blind trials: in male infertility, the pregnancy rate did not rise significantly more than on placebo; in depression, symptoms improved just as much on placebo; and in androgen deficiency, testosterone undecanoate had a clearly stronger effect on libido, erections and mood. It has also been measured that mesterolone lowers the body’s own testosterone. There is no study on muscle building; the package leaflet explicitly warns against it. In Germany the substance is prescription-only, is listed in the annex of the Anti-Doping Act and is banned in sport at all times.
What it is and how it works
Chemically, mesterolone is 1α-methyl-dihydrotestosterone. Unlike most steroids in tablet form, it carries no 17α-alkyl group. It originally came from Schering; today Bayer markets it as Proviron. According to the package leaflet, it is intended for men who produce too little male hormone because of a dysfunction of the testes, and it promotes the growth, development and function of androgen-dependent organs.
It binds to the androgen receptor like testosterone. What has been measured in humans is the feedback on the hormonal axis: in a trial with 52 men, total testosterone and bound testosterone fell markedly on mesterolone (Itil 1984). As a substitute for testosterone, it fell short of testosterone undecanoate in a direct comparison trial (Luisi 1980). More on medical testosterone therapy can be found under Testosterone; an overview of the whole substance group is under Anabolic steroids (AAS).
What is well supported
Mesterolone is a medicine with an approval, contraindications and documented side effects; in 2019 it had national approvals in Hungary, Slovakia, Italy, Malta, Spain, Greece and Portugal, among others, and today also in Belgium and Luxembourg. For two questions there are also clean, double-blind trials: male infertility and depression in men. Both answers are clear – an advantage over placebo could not be shown. It is also well supported that the body’s own testosterone falls on mesterolone.
What the studies show
WHO trial on male infertility
Seven centers, 248 couples, double-blind and randomized, two mesterolone groups against placebo over 6 months. After 8 months, the pregnancy rates were 9 % on placebo and 12 % and 16 % in the mesterolone groups; the differences were not significant. Sperm quality did not change, apart from a temporary rise in concentration that was largest on placebo (WHO Task Force 1989).
Second fertility trial over 12 months
52 men with unexplained impaired sperm quality, double-blind against placebo. Sperm motility and morphology improved on mesterolone, but equally on placebo; the pregnancy rate was 26 % on mesterolone and 48 % on placebo. The authors doubted the benefit (Gerris 1991).
Depression in men
52 depressed male outpatients aged 26 to 53, double-blind against placebo over 6 weeks. Symptoms improved markedly on mesterolone, but also on placebo; there was no statistical difference. Mesterolone lowered testosterone in the blood (Itil 1984).
Comparison with testosterone undecanoate in androgen deficiency
26 men with hypogonadism, double-blind and randomized. After 4 weeks, libido, erections, ejaculations and mood were significantly better on testosterone undecanoate than on mesterolone (Luisi 1980).
Coagulation in healthy men
After a deep vein thrombosis in a patient taking mesterolone, 9 healthy men received the drug for 21 days. None of the measured coagulation and blood values changed significantly (Lowe 1979).
Where the data stop
The studies date from 1979 to 1991, are small and have not been repeated with modern methods. For the approved indication itself, androgen deficiency, the sources reviewed here contain only the comparison with testosterone undecanoate, in which mesterolone performed worse.
The expectations with which mesterolone is used outside medicine, for example as an add-on to other steroids, have not been studied in humans. There is no study on muscle building, body fat, performance or use in healthy men, and no controlled long-term data on the heart and liver.
Status, approval and legal
In Germany, no product is currently on the market (Gelbe Liste, as of 10/2026: substance without an assigned product); Germany is not listed in the 2019 EMA list of nationally authorised products. Mesterolone and its esters are prescription-only under Annex 1 of the German Medicinal Products Prescription Ordinance (AMVV). In Belgium and Luxembourg, Proviron is approved as a prescription-only medicine; the package leaflet was last approved in July 2024. Mesterolone is listed by name in the annex of the German Anti-Doping Act: trading, supplying and prescribing for doping purposes are prohibited (§ 2(1)), as are acquiring and possessing a non-small quantity for doping in sport (§ 2(3)). On the WADA Prohibited List 2026 it is listed under S1.1 and banned at all times.
Safety
The package leaflet mentions rare benign and even rarer malignant liver tumors after hormonal substances of this kind, occasionally with life-threatening bleeding into the abdominal cavity; persistent upper abdominal complaints therefore need to be checked by a doctor. As side effects it lists frequent or prolonged erections up to priapism, water and salt retention, acne, hair loss, headache and abdominal pain; contraindications are prostate cancer and liver tumors. It explicitly warns against use for muscle building in healthy people, because of serious risks to the heart and blood vessels up to death, to the liver and to mental health, and because of dependence. It has been measured that the body’s own testosterone falls on mesterolone (Itil 1984). For coagulation values, a short study in 9 healthy men found no change (Lowe 1979). Every step here should be preceded by a conversation with a doctor – not as a formality, but because of consequences that can be lasting.
BK-Score Thin human evidence
| Human evidence | 5 | |
|---|---|---|
| Mechanism | 7 | |
| Safety data | 6 | |
| Hype gap | 4 | |
| Track record of use | 8 |
Evidence 5, because several randomized, double-blind trials exist, but they showed no advantage for the purposes tested: in male infertility no significantly higher pregnancy rate than on placebo (WHO trial with 248 couples 1989, Gerris 1991 with 52 men), in depression no difference from placebo (Itil 1984, 52 men), in androgen deficiency weaker than testosterone undecanoate (Luisi 1980, 26 patients); the studies are old, small and say little about the approved indication itself. Mechanism 7, because mesterolone is known as a DHT derivative acting on the androgen receptor and the fall in the body’s own testosterone has been measured in humans (Itil 1984), but effects on muscle, fat and the heart have not. Safety 6, because there is an approval with a package leaflet and decades of post-marketing surveillance (Belgium, approved 07/2024) and a coagulation study in 9 healthy men (Lowe 1979), but no controlled long-term data. Hype 4, because outside medicine it is regarded as a harmless add-on, for which there is no study, while the package leaflet explicitly warns against use for muscle building. Use 8, because Proviron has been approved as a prescription-only medicine in several EU countries for decades (EMA list 2019), but is currently not on the market in Germany. Direction mixed: approved for androgen deficiency, without advantage in the randomized trials on infertility and depression.
The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)
Frequently asked questions about mesterolone
Is mesterolone approved in Germany?
No product is currently on the market in Germany. The substance is prescription-only, and in several EU countries, such as Belgium, Luxembourg, Italy, Spain and Portugal, Proviron is approved for androgen deficiency in men.
Does mesterolone help when trying to conceive?
Not in the studies. In the WHO trial with 248 couples, the pregnancy rate was not significantly higher than on placebo; in a second trial with 52 men it was even lower on mesterolone.
Does mesterolone help with depression?
In the placebo-controlled trial with 52 depressed men, symptoms improved equally on mesterolone and on placebo. The trial showed no advantage for the drug.
Is mesterolone a substitute for testosterone?
In the only direct comparison trial in men with androgen deficiency, testosterone undecanoate had a clearly stronger effect on libido, erections and mood after 4 weeks. The standard treatment for proven deficiency is testosterone.
Does mesterolone lower the body’s own testosterone?
Yes. In a trial with 52 men, total testosterone and bound testosterone fell markedly on mesterolone.
Is mesterolone banned in sport?
Yes. It is on the WADA Prohibited List under S1.1 and is banned at all times. In Germany it is also listed by name in the annex of the Anti-Doping Act.
Related
- Related topicFluoxymesterone (Halotestin)
- Related topicTrestolone (MENT)
- Related topicDrostanolone (Masteron)
- Related topicOral Turinabol (dehydrochlormethyltestosterone)
- Related topicMethandrostenolone (Dianabol)
- Related topicStanozolol (Winstrol)
Sources
- Package leaflet Proviron tablets, Belgium and Luxembourg (FAGG, approved 07/2024)
- EMA 2019 – list of nationally authorised medicinal products containing mesterolone (PSUSA/00010551/201901)
- WHO Task Force, Int J Androl 1989 – mesterolone in idiopathic male infertility, double-blind, 248 couples
- Gerris J et al., Fertil Steril 1991 – placebo-controlled trial, high-dose mesterolone in male infertility, 52 men
- Itil TM et al., Methods Find Exp Clin Pharmacol 1984 – mesterolone in depressed men, double-blind, placebo-controlled
- Luisi M, Franchi F, J Endocrinol Invest 1980 – testosterone undecanoate versus mesterolone in androgen deficiency, double-blind
- Lowe GD et al., Br J Clin Pharmacol 1979 – thrombosis on mesterolone and coagulation study in 9 healthy men
- German Medicinal Products Prescription Ordinance (AMVV), Annex 1: mesterolone and its esters
- German Anti-Doping Act (AntiDopG), § 2 and annex
- Prohibited List in sport 2026: S1.1 anabolic androgenic steroids (WADA Prohibited List)
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-05.