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What Is Proviron (Mesterolone)?

Proviron is the long-standing brand name for mesterolone, an orally active androgen developed by Schering and on the market since 1934 — making it one of the oldest synthetic androgens still in use. This listing is 25 mg per tablet, 50 tablets per bottle.

Chemically it is 1α-methyl-dihydrotestosterone — DHT with a methyl group at the 1-position. That single detail explains almost everything about how it behaves, including the property that makes it unusual among oral compounds.

The Oral That Is Not Liver Toxic

Almost every orally active steroid achieves that oral activity through 17α-alkylation, the modification that lets a compound survive first-pass liver metabolism — and the same modification responsible for the hepatic strain associated with Dianabol, Turinabol, Winstrol and Anavar.

Mesterolone is different. It is methylated at the 1-position, not the 17-position, which grants oral bioavailability without the 17α-alkyl group. The practical result is an oral compound that does not carry the characteristic hepatotoxicity of the class. It is not a licence to ignore bloodwork, but it does mean Proviron does not stack liver load the way another methylated oral would.

Product Details

• Compound: Mesterolone (Proviron)
• Strength: 25 mg per tablet
• Count: 50 tablets per bottle
• Form: Oral tablet, 1-methylated (not 17α-alkylated)
• Half-life: Approximately 12 hours
• Aromatisation: None
• Class: DHT-derived androgen, DEA Schedule III
• Shipping: US domestic, 3–5 business days

What Proviron Actually Does — and the Myth It Is Sold On

Proviron is widely marketed as an anti-estrogen, and people buy it expecting it to replace an aromatase inhibitor. It will not. Selling it that way is the most common misrepresentation attached to this compound, and it leads people to skip an AI they actually need.

What mesterolone genuinely does is more interesting, and it operates through two distinct mechanisms:

It binds SHBG strongly. Sex hormone-binding globulin binds circulating testosterone and renders it biologically unavailable. Mesterolone has a high affinity for SHBG, and by occupying it, more of the testosterone already in your system remains free and active. You have not added testosterone — you have freed up what was already there. This is the main reason Proviron is run alongside a testosterone base rather than on its own.

It interacts weakly with aromatase. As a DHT derivative, mesterolone acts as a weak competitive substrate at the aromatase enzyme. The effect is real but modest. It is not remotely comparable to anastrozole or exemestane, and it should never be the plan for controlling estrogen on an aromatising cycle.

Mesterolone is itself strongly androgenic and only weakly anabolic. Nobody runs Proviron to build muscle, and any page suggesting otherwise is not being straight with you.

Why People Actually Use It

• Libido. This is the most consistently reported effect by a wide margin, and it follows directly from the SHBG mechanism — more free testosterone and a strongly androgenic compound in circulation. It is frequently used to address the flat libido that accompanies heavily suppressive compounds, particularly the non-aromatising ones such as trenbolone.
• Physique hardness. As a non-aromatising DHT derivative, mesterolone adds a dry, dense quality to an already lean physique. It does nothing visible at higher body fat — this is a finishing tool, not a transformative one.
• Free testosterone. The SHBG effect makes an existing testosterone dose work harder without raising the dose itself.

Dosing and Half-Life

Mesterolone has a half-life of roughly 12 hours, which is short enough that splitting the daily amount across two doses produces more stable blood levels than a single dose. Because it is not 17α-alkylated, run duration is not constrained by hepatic load the way it is with other orals — the practical limits are androgenic side effects and its suppressive effect.

Specific protocols are a decision for you and a qualified physician, and this page does not make a recommendation.

Side Effects

• Suppression — Proviron is often described as non-suppressive. That is not accurate. It is an androgen and it does suppress the HPG axis, generally less severely than most AAS but meaningfully.
• Androgenic effects — as a DHT derivative it is strongly androgenic. Acne, oily skin, and accelerated male pattern hair loss in genetically predisposed users are the most common complaints, and hair loss is a more frequent report with mesterolone than with milder compounds.
• Prostate effects — DHT derivatives act directly on prostate tissue; relevant to older users in particular.
• Lipid changes — reduced HDL, typical of oral androgens.
• No estrogenic effects — mesterolone does not aromatise, so it produces no water retention or estrogen-driven gynecomastia on its own.

Proviron vs Masteron vs an Aromatase Inhibitor

• Proviron vs Masteron: close relatives — mesterolone is oral, drostanolone injectable, both DHT-derived, both non-aromatising, both used for dryness and hardness. Masteron is the more anabolic of the two; Proviron is the more convenient and the stronger performer on libido and SHBG.
• Proviron vs Arimidex / Aromasin: not substitutes. An aromatase inhibitor directly and substantially suppresses estrogen conversion. Proviron’s aromatase interaction is weak. If you need estrogen control, use an AI and use it from bloodwork.
• Proviron vs Nolvadex: different mechanisms entirely. Tamoxifen blocks the estrogen receptor in breast tissue; mesterolone does not. They are not interchangeable.

What Proviron Pairs With

Proviron is an addition, not a foundation. It is most commonly run alongside a testosterone base — Test E, Test C, Test P or Sustanon — where the SHBG effect frees up more of that testosterone. It is also frequently added to non-aromatising compounds such as trenbolone, where low libido is a common complaint.

Because it suppresses natural production, it is not a post-cycle therapy compound. Recovery protocols use Nolvadex, Clomid, enclomiphene and HCG instead — running an androgen during PCT works against the goal.

Where to Buy Proviron in the US

KGEAR U.S ships Proviron (mesterolone) 25 mg, 50 tablets domestically within the United States, typically arriving in 3–5 business days. Orders are placed on this page and payment is by Bitcoin. Please note the store minimum: at least 2 items and a cart total over $100. New to crypto? Our guide to buying Bitcoin covers it step by step.

Browse the rest of our ancillaries range — including Arimidex, Aromasin, Nolvadex and enclomiphene — or our oral range.

Proviron — Frequently Asked Questions

What is Proviron used for?
Mesterolone is used alongside a testosterone base to increase free testosterone by binding SHBG, to support libido, and to add dryness and hardness to an already lean physique. It is weakly anabolic and is not used to build muscle.

Is Proviron an aromatase inhibitor?
No. It interacts weakly with the aromatase enzyme, but the effect is modest and it is not a substitute for anastrozole or exemestane. Treating it as an AI is the most common and most costly mistake made with this compound.

Is Proviron liver toxic?
It is methylated at the 1-position rather than the 17-position, so it is orally active without the 17α-alkyl group responsible for the hepatotoxicity of most oral steroids. It does not carry that same liver burden.

Does Proviron suppress testosterone?
Yes. It is frequently described as non-suppressive, which is inaccurate. Suppression is generally milder than with most AAS but it is real.

What is the half-life of mesterolone?
Approximately 12 hours, so splitting the daily amount into two doses gives steadier blood levels.

Proviron or Masteron?
They are close relatives with the same DHT origin and similar dry, hardening effects. Masteron is injectable and more anabolic; Proviron is oral and the stronger option for libido and free testosterone.

Can Proviron be used in PCT?
No. It is an androgen and it suppresses natural production, which is the opposite of what post-cycle therapy is trying to achieve.

What does Proviron cost and how do I order?
Pricing is shown at the top of this page. Orders are placed on-site and paid by Bitcoin, with a minimum of 2 items and a cart total over $100, shipped US domestic in 3–5 business days.

Disclaimer: This information is provided for educational purposes only and is not medical advice. Mesterolone is a DEA Schedule III controlled substance and is not approved by the FDA for human use in the United States. Anabolic-androgenic steroids and related androgens carry real risks, including cardiovascular, hormonal and psychological effects. Nothing on this page should be taken as encouragement to use this product, and no statement here has been evaluated by the FDA. Consult a qualified physician before making any decision about your health.