Lower numbers = closer to natural. Higher numbers = more enhanced.
Why this rating?
Pharmacology references describe mesterolone as "a very poor anabolic agent" that is "not commonly used for [physique-enhancing] purposes due to its weak anabolic effects". Its role in a cycle is almost entirely as a support compound (SHBG binding to raise free testosterone, libido enhancement, mild hardening) rather than as a muscle builder. It also does not significantly suppress natural testosterone at moderate solo doses (25-75mg/day) and needs no PCT alone. Because it does not meaningfully add muscle tissue on its own, it sits near the bottom of the natty scale, a notch above a pure AI/SERM only because it is a genuine controlled anabolic-androgenic steroid with real, if weak, androgenic activity.
Overview
An oral androgen used to increase free testosterone and enhance libido. Unlike most orals, it is not 17-alpha-alkylated and is not hepatotoxic.
Purpose & Use Cases
Free Testosterone Enhancement
Increases free testosterone by binding to SHBG, making other steroids more effective.
Libido Enhancement
Dramatically improves libido and sexual function.
Hardening Effect
Provides mild hardening and drying of the physique.
Non-Aromatizing
Not a substrate for aromatase, so it adds no estrogenic load of its own, sometimes used clinically to offset gynecomastia/breast tenderness in low-testosterone states. This comes from the absence of estrogenic activity, not from confirmed estrogen-receptor blockade.
Benefits
- Increased free testosterone via SHBG binding
- Significantly enhanced libido
- Mild physique hardening
- Anti-estrogenic properties
- Not liver toxic
- Well-tolerated long-term
Good to Know
A support compound, not a mass builder
Proviron barely builds muscle, pharmacology references describe it as "a very poor anabolic agent." Its real value is binding SHBG to raise free testosterone, adding no estrogenic load of its own (it doesn't aromatize), and a strong libido boost. It makes a cycle "feel" and look better rather than adding size on its own.
Not 17-alpha-alkylated: the rare liver-friendly oral
Unlike almost every other oral steroid, mesterolone is not 17aa and is not hepatotoxic, so it can be run for longer stretches without the usual liver concern or TUDCA requirement.
A DHT-derivative: finasteride does nothing
Proviron is already a DHT derivative, so there is no testosterone-to-DHT conversion for finasteride/dutasteride to block. If you are DHT-prone it can nudge hair loss along, and a 5-AR inhibitor will not help.
"No PCT" is only true at modest solo doses
At 25-75mg/day alone it is only mildly suppressive, so PCT is often unnecessary, but it is not truly non-suppressive at higher doses, and when stacked with suppressive compounds the PCT for those still applies.
Dosage Guidelines
| Experience Level | Dosage Range |
|---|---|
| Beginner | 25 – 50 mg/day |
| Intermediate | 50 – 100 mg/day |
| Advanced | 100 – 150 mg/day |
Can be run longer than most orals due to lack of hepatotoxicity.
Side Effects
Hair Loss
commonAs a DHT derivative, it can accelerate hair loss in predisposed individuals.
Topical minoxidil; avoid if hair is priority.
Prostate Strain
uncommonCan exacerbate prostate issues due to androgenic activity.
Monitor PSA levels; avoid with existing prostate issues.
Lipid Disruption
uncommonMild negative impact on cholesterol.
Omega-3s and cardiovascular exercise.
General Mitigation Strategies
Monitor lipids and prostate health. One of the mildest orals for side effects. Not liver toxic so no hepatoprotection needed.
Support Supplements
Ancillary supplements commonly run alongside Proviron to manage side effects, support the target tissue, or fill nutrient demands it creates.
Lipid support (omega-3 + citrus bergamot)
As a DHT-derivative Proviron can trim HDL, though mildly. Omega-3 helps triglycerides; citrus bergamot lowers LDL via statin-like flavonoids.
- Dose
- Omega-3 2-4 g/day; citrus bergamot 500-1,000 mg/day
- Timing
- With meals
- When
- Low priority when Proviron is run alone; more relevant when it is added to a fuller cycle that already stresses lipids.
Post Cycle Therapy (PCT)
Does not significantly suppress natural testosterone when used alone at moderate doses. If stacked with suppressive compounds, standard PCT for those compounds applies.
How It Works
Proviron binds strongly to SHBG (Sex Hormone Binding Globulin), freeing up more testosterone to be active. As a DHT derivative it is not a substrate for aromatase, so it adds no estrogenic load of its own and provides DHT-like androgenic effects; claims that it actively blocks estrogen at the receptor are common in community lore but are not established in the clinical literature.
Hormonal & Androgenic Profile
Real-world potency is weak anabolic / moderate-to-strong androgenic, pharmacology literature calls mesterolone "a very poor anabolic agent." (Published numeric anabolic:androgenic lab ratings for mesterolone are reported inconsistently, and in conflicting order, across sources, so no specific number is cited here.)
Not a substrate for aromatase, so it does not convert to estrogen and no AI is needed for Proviron itself. Community claims that it actively "blunts" estrogen from aromatizing stack-mates are common but not clearly substantiated in the clinical literature. Its real anti-estrogenic value is that it adds zero estrogenic load of its own.
A DHT-derivative (already past 5-alpha-reductase), so finasteride/dutasteride are useless. There is nothing to block. Its androgenic hair/prostate effects cannot be softened with a 5-AR inhibitor.
Mild lipid impact as a DHT-derivative; no water retention or estrogenic BP rise. Generally well tolerated over long runs.
Fundamentals
Reference on the practices relevant to Proviron: how they are done and where they go wrong. Not a recommendation to use it.
Common Stacks
- Proviron + any cycle - Enhances free testosterone
- Proviron + TRT - Libido enhancement
- Proviron + Nandrolone - Helps prevent Deca Dick
Legal Status
Schedule III controlled substance (USA).
Legal status varies by country and changes over time. This is a general summary, not legal advice.
WADA Status
Mesterolone (Proviron) is explicitly prohibited as an anabolic androgenic steroid.