Mesterolone (Proviron)
Proviron
Oral DHT derivative; low bioavailability, used for SHBG binding / anti-estrogenic effect.
Key takeaways
- Oral DHT derivative (Proviron); strong SHBG binder, weakly anabolic, doesn't aromatize.
- ~12.5-hour half-life and ~3% bioavailability; daily dosing, sometimes split.
- Not 17-alpha-alkylated (1-methyl instead), so hepatotoxicity is mild.
- Weak HPTA suppression at clinical doses; androgenic sides are the realistic concern.
Overview
What it is
Mesterolone (Proviron) is an oral DHT derivative, still prescribed in some countries for male hypogonadism and infertility. A 1-methyl group replaces the usual 17-alpha-alkylation, so liver strain stays mild. Its practical value comes from strong SHBG binding and a mild anti-estrogenic effect rather than tissue building; it's barely anabolic at all.
Pharmacokinetics
The dataset lists a ~12.5-hour half-life, a peak around 1.6 hours, Cmax near 400 ng/dL, and just 3% bioavailability from heavy first-pass loss. Daily dosing, sometimes split, keeps levels from swinging.
Harm reduction
It doesn't aromatize, suppresses the HPTA only weakly at clinical doses, and rates mild on hepatotoxicity. The realistic concerns are androgenic (hair, prostate), a possible lipid shift at higher doses, and added suppression on top of an existing stack.
Reported dosing protocols
Protocols reported in research literature and clinic/community use — informational context, not a dosing recommendation.
| Use case | Dose | Route | Frequency | Duration |
|---|---|---|---|---|
| Androgen deficiency / infertility (label) | 75–100 mg daily initially | Oral | Split 2–3× daily | Ongoing (maintenance lower) |
| Adjunct / SHBG lowering (community) | 25–50 mg daily | Oral | Daily or split 2× | 4–8 weeks |
Pharmacokinetic summary
- Model tier
- Advanced (t½ + Cmax + Tmax + F)
- Half-life
- 12.5 hours
- Cmax
- 400 ng/dL
- Tmax
- 0.1 days
- Bioavailability
- 3%
- Typical dose
- 25–100 mg
Harm reduction
- Aromatizes
- No
- DHT derivative
- Yes
- Hepatotoxicity
- mild
- Injection frequency
- Oral, daily
Frequently asked questions
Is Proviron actually anabolic?
Barely. Mesterolone binds the androgen receptor but is rapidly inactivated in muscle tissue, so its tissue-building effect is negligible. Its practical roles are SHBG binding (raising free hormone fractions) and a mild anti-estrogenic effect, not mass gain.
Does Proviron suppress natural testosterone?
Weakly at clinical doses (25–75 mg daily), which is why it's prescribed for androgen deficiency without full shutdown. At the higher doses reported in performance contexts, some suppression does occur and it stacks on top of whatever else is suppressive.
Why is the bioavailability so low?
Mesterolone isn't 17-alpha-alkylated, so the liver clears most of each oral dose on first pass — the dataset lists ~3%. That trade is deliberate: hepatotoxicity stays mild where alkylated orals are harsher.
References
- Bayer Proviron PI
- Bayer Proviron prescribing information — Label dosing, pharmacology, and safety data for mesterolone.
Related compounds
Testosterone Enanthate
Long-acting testosterone ester; the most common TRT and cycle base. Reaches steady state in ~5 weeks.
Testosterone Cypionate
Standard US TRT ester with a slightly longer release tail than enanthate. Steady state ~4–5 weeks.
Testosterone Propionate
Short-acting ester with sharp peaks; requires frequent injection. Useful for frontloading.
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