Proviron (Mesterolone) Effects, Side Effects, and Uses

Proviron is the brand name for the androgen mesterolone.

It is an oral product with very weak anabolic effects, so it is not considered an anabolic steroid.

In fact, it has almost no anabolic effects.

Proviron was first developed by Schering in 1934 and is one of the oldest steroids manufactured for medical use.

It is an old product that was used alongside methyltestosterone in 1935 and testosterone propionate in 1937.

While methyltestosterone and testosterone propionate became widely known as powerful anabolic agents, Proviron received less attention due to its weak effects.

Nevertheless, Proviron is still used as a pharmaceutical and has proven to be safe and well-tolerated.

Proviron is used to treat age-related health decline, sexual dysfunction, and infertility in elderly men caused by decreased androgen levels.

It is particularly notable as an infertility aid due to its characteristic of having almost no suppression of endogenous gonadotropins (LH and FSH).

Contrary to misunderstanding, it does not increase LH, but it provides the androgenic effect necessary for spermatogenesis in the testes.

Bayer Schering still manufactures and sells mesterolone under the name Proviron worldwide, and it is also distributed under other brand names such as Pluriviron and Vistimon.

Interestingly, Proviron is not an FDA-approved drug in the US prescription market.

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Chemical Properties of Proviron

Proviron is a modified derivative of dihydrotestosterone (DHT), specifically 1-methyl dihydrotestosterone with a methyl group added at the 1-carbon position.

Due to its weak anabolic activity, it is primarily classified as an androgenic steroid.

Research indicates that Proviron, similar to DHT, is rapidly metabolized into inactive metabolites when it enters muscle tissue.

In muscle tissue, the enzyme 3-hydroxysteroid dehydrogenase binds to DHT and inactivates its anabolic effects, which is why Proviron has weak anabolic effects.

There is a misconception in the bodybuilding community that Proviron blocks androgen receptors in muscle tissue, but this is incorrect information.

Proviron has a high affinity for Sex Hormone-Binding Globulin (SHBG), binding to SHBG and helping more free testosterone to act without interfering with anabolic steroid activation.

Additionally, Proviron acts as an aromatase inhibitor and can function as an anti-estrogen, although it is not as potent as Arimidex or Aromasin.

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Proviron Side Effects

Since Proviron is a DHT derivative, there is no risk of estrogenic side effects at any dosage.

It acts as an aromatase inhibitor, providing anti-estrogenic effects and reducing plasma estrogen levels, thereby mitigating the estrogenic side effects of other compounds.

This combination of androgenic properties and anti-estrogenic function is why it is used for treating gynecomastia and breast cancer.

However, Proviron carries a risk of androgenic side effects, which become more pronounced at higher doses.

Side effects include increased oily skin, body hair growth, and the risk of male pattern baldness in men with a genetic predisposition.

Women may develop masculine characteristics.

Finasteride or Dutasteride cannot reduce the androgenic side effects.

Proviron is not C-17 alpha alkylated, so there is almost no risk of liver toxicity.

However, cardiovascular side effects can occur, with reported increases in LDL and decreases in HDL after taking 100mg daily for 6 months.

Its effect on suppressing endogenous testosterone is weak, so it can be used at doses of 150mg per day or less without significant suppression.

However, at high doses of 300mg or more, noticeable testosterone suppression occurs.

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Proviron Administration and Management

In the medical field, treatment for male hypogonadism begins with taking one 25mg tablet three times a day (total 75mg), then reducing to a maintenance dose of 25mg per day.

This dosage is also used for treating male infertility, combined with fertility improvement medications.

Bodybuilders and athletes take 50-150mg of Proviron daily to regulate estrogen levels, reduce water retention, or aid post-cycle fertility recovery.

Proviron is not approved for use in women, but some female bodybuilders use 25mg per day for physique improvement.

To prevent virilization effects, it is recommended not to use it for more than 4-5 weeks.

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Proviron Cycles and Uses

Proviron is not used alone in cycles because its anabolic effects are extremely weak.

Instead, it is utilized as an ancillary drug in anabolic steroid cycles to minimize or mitigate estrogenic effects.

Its potent androgenic and anti-estrogenic effects provide an aesthetic benefit, making the physique appear “harder.”

Male athletes and bodybuilders take 50-100mg daily as an ancillary supplement and can use it without restriction throughout their training cycles.

Some people also use it as a PCT drug to lower estrogen levels and improve fertility, but there are more potent and effective alternatives for PCT.

Due to the risk of endogenous testosterone suppression, it is best to avoid using Proviron for PCT purposes, and any potential threat, however minimal, should be excluded during natural testosterone recovery.