- Proviron is mesterolone, an oral DHT derivative prescribed in some countries for low testosterone and male infertility.
- It’s weakly anabolic, so it’s used as a supporting compound rather than for muscle growth.
- It isn’t 17-alpha-alkylated, so it’s much easier on the liver than most orals.
- Claims that it blocks estrogen are overstated. It doesn’t aromatize, but it isn’t an aromatase inhibitor.
Proviron is an unusual steroid. It builds very little muscle, yet it’s been part of bodybuilders’ toolkits for decades. This guide explains what mesterolone actually does, what the evidence supports, its side effects, and what Canadians should know.
What is Proviron?
Mesterolone is a dihydrotestosterone (DHT) derivative with a methyl group at the 1-position. It was introduced in the 1960s and is still prescribed in parts of Europe and elsewhere for male hypogonadism (low testosterone) and some forms of male infertility. It isn’t marketed in Canada.
Unlike most oral steroids it isn’t 17-alpha-alkylated, so it’s far less stressful on the liver. It’s also broken down quickly in muscle tissue, which is why its anabolic effect is weak.
Why people use it
- Libido and well-being, as an androgen that doesn’t convert to estrogen
- Binding SHBG. Mesterolone binds sex hormone-binding globulin strongly, which may leave more of other hormones free in the blood
- A harder look when lean, similar to other DHT derivatives
About estrogen: you’ll often read that Proviron “blocks estrogen”. It doesn’t convert to estrogen itself, but there’s little evidence it meaningfully lowers estrogen made from other steroids. It isn’t a substitute for an aromatase inhibitor.
Clinical reference doses
For male hypogonadism, the European label for 25 mg tablets typically starts at one tablet three or four times a day for several months, followed by a maintenance dose of one or two tablets daily. These figures are for reference only.
Side effects
- Hair loss and acne in people prone to them, as a DHT derivative
- Prostate: androgens can enlarge the prostate; men over 40 should have a PSA test
- Cholesterol: HDL may fall
- Suppression: at higher doses it can lower natural testosterone
- Women: virilization, including voice deepening, which can be permanent
Bloodwork in Canada
Check testosterone, estradiol, a lipid panel, liver enzymes and PSA (over 40). Ask your family doctor or book privately at LifeLabs or Dynacare.
Is Proviron legal in Canada?
Mesterolone is an anabolic steroid, listed in Schedule IV of the Controlled Drugs and Substances Act. Possessing it for personal use isn’t an offence; trafficking, importing and exporting without authorization are.
Buying Proviron in Canada
We stock Zionova Proviron, 20 mg mesterolone tablets in bottles of 50. Live prices are on the product page and the oral steroids page. Older posts here covered Norma Pharma Proviron, which we no longer stock.
Frequently asked questions
What does Proviron do?
It’s a mild oral androgen that doesn’t convert to estrogen. It’s used medically for low testosterone, and by bodybuilders for libido, SHBG binding and a harder look.
Is Proviron an anti-estrogen?
Not really. It doesn’t aromatize, but it isn’t an aromatase inhibitor and doesn’t reliably lower estrogen from other steroids.
Is Proviron hard on the liver?
No more than mildly. It isn’t 17-alpha-alkylated, unlike most oral steroids.
Does Proviron build muscle?
Very little. It’s broken down quickly in muscle tissue, so its anabolic effect is weak.
Is Proviron legal in Canada?
It’s Schedule IV under the CDSA. Personal possession isn’t an offence; trafficking, importing and exporting without authorization are.
Products mentioned in this guide
This article is general information for adults in Canada, not medical advice. Talk to a doctor or pharmacist before using any prescription drug, anabolic steroid or research compound, and get bloodwork done. If you’re in crisis, call or text 9-8-8 (Suicide Crisis Helpline) any time.
