Proviron (Mesterolone): An Oral Androgen That Is Not a Steroid Cycle
Proviron is one of the few oral androgens that is easy on the liver. It is also weakly anabolic. Here is where it fits and where it does not.
SteroidsCanada.org editorial teamUpdated · 3 min read
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Proviron is the brand name for mesterolone, an oral androgen first sold in the 1960s. In several countries outside North America it is still prescribed for low testosterone and some forms of male infertility. It is also one of the most misunderstood compounds in the gym world, where it is often described as an estrogen blocker.
What mesterolone is
Mesterolone is DHT with a methyl group at the first carbon. Unlike most oral steroids, it is not 17-alpha-alkylated, the modification that lets tablets survive the liver but also makes them toxic to it. Mesterolone is absorbed reasonably well anyway, which is why it is considered liver-friendly compared with tablets like Dianabol or Anadrol.
How it is prescribed
Where approved, mesterolone is used for androgen deficiency and some types of male infertility, at 25 to 75 mg a day split into doses. Its role has shrunk as testosterone gels and injections took over hypogonadism treatment.
What it does and does not do
- Does: act as a strong androgen in tissues like skin, scalp and the brain, which users report as better libido and mood.
- Does: bind sex hormone-binding globulin (SHBG), which may free up more of the testosterone already in your blood.
- Does not: build much muscle by itself. In muscle tissue it is broken down quickly.
- Does not: reliably control estrogen. Claims that it works like an aromatase inhibitor are not supported by good human data.
Side effects
Acne, oily skin, hair thinning in prone men, prostate enlargement and lower HDL are the main ones. It can cause some suppression of natural testosterone at higher amounts. In women it is strongly masculinising.
A short history
Schering introduced mesterolone in the 1960s as Proviron. Because it is not 17-alpha-alkylated and is well tolerated, it was prescribed for decades in Europe, the Middle East and parts of Asia for androgen deficiency and as a treatment for some forms of male infertility. It was never approved in the United States or marketed in Canada. Its use in bodybuilding grew mainly from its reputation for improving libido and hardness while being easy on the liver.
Proviron and fertility
Older studies suggested mesterolone could improve sperm quality in some men with low counts, because at modest amounts it suppresses the brain’s hormone signals less than testosterone does. Later controlled studies were less convincing. Fertility clinics today rarely use it; anyone trying to conceive should see a fertility specialist rather than relying on it.
Who should avoid it
- Men with prostate cancer or significant prostate enlargement
- Anyone with low HDL or a strong family history of heart disease
- Men prone to male-pattern hair loss who want to keep their hair
- Women, because of its strongly androgenic action
- Anyone under 21
Myths and facts
| Myth | Fact |
|---|---|
| Proviron is an anti-estrogen | It is an androgen. Any effect on estrogen is indirect and unreliable; it is not a substitute for medical estrogen control. |
| Proviron raises your own testosterone | It can free up more testosterone by binding SHBG, but it does not stimulate the testes; at higher amounts it suppresses them. |
| Proviron is completely safe for the liver | It is far gentler than 17-alpha-alkylated orals, but any drug can affect the liver in some people. |
Interactions
As with other androgens, mesterolone can strengthen the effect of warfarin and lower blood sugar in people taking diabetes medicines. Tell your pharmacist if you use it.
Bloodwork
Lipid panel, PSA (men over 40), total testosterone, LH, and liver enzymes for a baseline.
Legal status
Mesterolone is a Schedule IV anabolic steroid in Canada. Personal possession is not an offence under the Controlled Drugs and Substances Act; selling, importing and exporting without authorisation are. It is not marketed as a medicine here and is banned in sport.
See Zionova Proviron for the tablet strength and chemistry.
Products in this guide
Each product page carries the chemistry, label strength, risks and references.
Questions
Does Proviron shut down testosterone?
At usual amounts it suppresses natural production less than most androgens, but it is not free of suppression, particularly at higher amounts.
Is Proviron an anti-estrogen?
It does not block estrogen receptors or aromatase in a strong, reliable way. It should not be treated as a substitute for medical estrogen control.
Is it available in Canada by prescription?
Mesterolone is not marketed in Canada, though it is approved in parts of Europe and elsewhere.
Can it cause hair loss?
Yes, like other DHT-derived androgens it can speed up male-pattern hair loss in prone men.
Sources
General information, not medical advice. Written for adults in Canada. Anabolic steroids are Schedule IV under the Controlled Drugs and Substances Act. Talk to a licensed healthcare provider and get bloodwork before using any compound.
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