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Muscle & performance

Proviron (Mesterolone)

The support compound - lowers SHBG, raises free testosterone, acts anti-estrogenic.

1 min read 10 sources

To the product To the sources
White tablet bottle with the black TPD label for mesterolone on a white podium, next to a blue 3D steroid molecule with four rings in a bright lab
Compound approved · according to ChEMBL, not in the USA

Summary

At a glance

Sources checked on 26 Oct 2026

Binding to SHBG
~4 -fold

compared with DHT, strongest SHBG binding among the steroids tested2

Pregnancies with mesterolone
26 %

52 men with reduced sperm quality, 12 months, with placebo 48%3

Largest fertility study
368 men

9 months against vitamin C, no difference in pregnancies4

Trials in the registry
0 trials

no trial with mesterolone on ClinicalTrials.gov, as of 26 Oct 20269

  • Mesterolone is a DHT derivative with a methyl group at position 1 and is taken by mouth. It is not 17α-alkylated.101
  • In the lab it bound SHBG most strongly of all steroids tested, about 4 times more strongly than DHT. It bound the androgen receptor more weakly than testosterone.2
  • In men with reduced sperm quality sperm motility and shape improved, but also with placebo. Pregnancies did not become more frequent, in two studies with 52 and 368 men.34
  • In hypogonadism testosterone undecanoate worked better on libido and mood in a small study. On the liver there is a case report, on blood clots one case and a study without findings.576
  • ChEMBL lists mesterolone as an approved substance, it is not approved in the USA. Everything here is the state of research, not a recommendation.8
Profile

Updated June 2026

How long does it stay in the body?

Share left after one dose, calculated with a half-life of ~12 hours

Half-life ~12 hours
After 24 hours: 25 %
Hour 12 · 50 %Hour 24 · 25 %Hour 36 · 12.5 %Hour 60 · 3.1 %

Simplified model without an absorption phase, half-life from the TPD lexicon.

Class
DHT derivative

oral, NOT 17a-alkylated

Use
Oral

1-2x per day

Half-life
about 12 hours
WADA
banned

anabolic

Sizes
25 mg

2 sizes in the shop

Contents 12 sections
  1. At a glance
  2. What is Proviron?
  3. How it works
  4. Use and dosing
  5. What the research shows
  6. Research status
  7. Side effects
  8. Storage
  9. Related compounds
  10. FAQ
  11. Glossary
  12. Sources

What is Proviron?

Proviron (Mesterolone) is an oral DHT derivative with a special role: it is not a mass-building steroid but a "support compound". It is not 17a-alkylated and therefore barely liver-loading. Clinically it was used for libido and fertility topics.

This information is for research and educational purposes only. No medical advice.

Comparison

Androgens in the lexicon

Mesterolone and related androgens, as described in the TPD lexicon. Tap a card to open its entry.

Oral DHT derivative Proviron (Mesterolone) ARSHBG
Methenolone as an ester Primobolan E (Methenolone Enanthate) AR Methyl-DHT as an ester Masteron P (Drostanolone Propionate) AR Testosterone as an ester Testosterone Enanthate AR

In the same lab study methenolone bound the androgen receptor more strongly than testosterone and mesterolone. Mesterolone instead stood out for its strong binding to SHBG. 2

How it works

Proviron binds strongly to SHBG (sex hormone binding globulin) and lowers it - raising the fraction of free, active testosterone in the blood. It also has a weak anti-estrogenic effect and binds the androgen receptor itself. That makes it a popular add-on compound that makes other steroids "freer" and more effective and supports well-being/libido.

Where it acts

Where mesterolone acted in studies

Tap a point or a card. Colour = target, grey = observed in studies.

  1. Blood (SHBG)

    Binds SHBG about 4 times more strongly than DHT2

    SHBG
  2. Muscle and prostate

    Binds the androgen receptor more weakly than testosterone (rats)2

    AR
  3. Testes

    Sperm more motile, but also with placebo, no more pregnancies3

    Observed in trials
  4. Libido and mood

    In hypogonadism weaker than testosterone undecanoate5

    Observed in trials
  5. Liver

    One case report of liver injury7

    Observed in trials

Known targets2

Compound PubChem CID 15020: two described targets, type of action on each card.

Sex hormone-binding globulin
Gene
SHBG
UniProt
P04278
ChEMBL
CHEMBL3305
Action
Binds strongly, about 4 times more than DHT
Androgen receptor
Gene
AR
UniProt
P10275
ChEMBL
CHEMBL1871
Action
Binds, more weakly than testosterone
Glass tubes through which blue four-ring steroid molecules flow towards a transparent cell and dock onto its surface
Mesterolone in the blood, bound to transport protein and receptor. Symbolic image.

Use and dosing

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts
White tablet bottle with the black TPD label for mesterolone against a light blue background, a few white tablets next to it
Symbolic image.

What the research shows

The AAS pharmacology (Kicman 2008) describes the SHBG binding and androgenic action of mesterolone. As a non-17a-alkylated DHT derivative the liver risk is low.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

How strongly mesterolone binds SHBG2

Relative binding, DHT = 1

Sex hormone-binding globulin2
DHT (reference) 1-fold
Mesterolone 4-fold

According to the abstract about 4 times stronger than DHT, order of SHBG binding: mesterolone ahead of DHT ahead of testosterone. At the androgen receptor in rat muscle and prostate mesterolone bound more weakly than testosterone, methenolone and nandrolone.

Pregnancies in 12 months3

52 men with reduced sperm quality, double-blind, share in percent

Partner pregnancy3
Mesterolone 26%
Placebo 48%

Similar according to the authors, no benefit from mesterolone. Sperm motility and shape improved, but also with placebo. A second study of 368 men over 9 months also found no difference compared with vitamin C.

Test tubes with clear liquid in a white rack, some holding white drop-shaped objects
The human studies date from 1979 to 1991. Symbolic image.

Research status

Where the research stands

Mesterolone is an old drug. The human studies date from before the registry, which lists not a single one. As of 26 Oct 2026. 9

  1. Preclinical Binding to SHBG and androgen receptor
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 no registered trial
  5. Approval according to ChEMBL, not in the USA
Approved: ChEMBL lists mesterolone with phase 4 as the highest phase (ATC code G03BB01). There is no US approval.8

The approval predates today's trial registries, so the register shows no current trial for this form. 9

Side effects

  • Androgenic (DHT derivative) - hair loss in predisposed individuals, acne.
  • Very low liver load (not 17a-alkylated).
  • HPTA suppression milder than with strongly anabolic steroids, but present.
  • Barely any estrogen side effects.

Storage

Store dry and cool, protected from light. Out of reach of children.

Three white tablet bottles and a folded light blue towel on a white shelf
Dry, cool and protected from light. Symbolic image.

Related

Related compounds

Same targets or a different path: all in the TPD lexicon.

Proviron (Mesterolone)
Masteron P (Drostanolone Propionate) Also a methylated DHT, as an injection Masteron E (Drostanolone Enanthate) Also a methylated DHT, long ester Primobolan E (Methenolone Enanthate) Binds the androgen receptor more strongly Testosterone Enanthate Testosterone itself Halotestin (Fluoxymesterone) Different oral androgen Finasteride Different path: lowers DHT production

FAQ

Common questions about Proviron (Mesterolone)

Short answers, each backed by the sources below.

Is mesterolone approved?

ChEMBL lists mesterolone as an approved substance with phase 4 as the highest phase and the ATC code G03BB01 (androgens). There is no approval in the USA and ClinicalTrials.gov lists no trial.89

What is special about the SHBG binding?

In a lab study mesterolone bound SHBG most strongly of all steroids tested, about 4 times more strongly than DHT. SHBG also binds testosterone in the blood. At the androgen receptor itself mesterolone bound more weakly than testosterone, methenolone and nandrolone.21

Does mesterolone help with infertility?

Not in two controlled studies. Among 52 men over 12 months 26 percent of partners became pregnant with mesterolone and 48 percent with placebo. Sperm motility and shape improved in both groups. Among 368 men over 9 months there was no difference compared with vitamin C, not even in subgroups.34

What is known about libido and mood?

In a small double-blind study of 26 men with hypogonadism testosterone undecanoate improved libido, erections and mood clearly more than mesterolone after 4 weeks.5

What about the liver and blood clots?

Mesterolone is not 17α-alkylated, so the classic liver strain of oral steroids is largely absent. A case report nevertheless describes a liver injury. After a blood clot in one patient researchers tested 9 healthy men over 3 weeks and found no change in clotting.176

Why are there no new studies?

The controlled studies of mesterolone were published between 1979 and 1991, before the registry existed. ClinicalTrials.gov lists no trial, newer papers mainly concern detection in doping tests and single cases.9637

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

17α-alkylated
Steroid with an extra group at position 17. It protects against breakdown in the liver when swallowed but strains the liver.
Androgen receptor
Protein inside the cell that testosterone and related compounds bind to. It switches on genes for muscle, bone and male traits.
ATC code
International classification of drugs by organ and action. G03BB stands for androgens of the 5-androstanone group.
DHT
Dihydrotestosterone: a potent androgen formed from testosterone. It is not converted to estrogen.
HPTA
Axis of hypothalamus, pituitary and testes that regulates the body's own testosterone production.
Hypogonadism
The testes make too little testosterone.
Oligozoospermia
Too few sperm in the ejaculate.
SHBG
Sex hormone-binding globulin: blood protein that binds testosterone and DHT. Bound hormone is inactive.
Thrombosis
Blood clot in a vessel that blocks blood flow.

Evidence

Sources

Show all 10 sourcesHide sources 7 Studies1 Trial registry2 Database checked 26 Oct 2026

Studies

  1. Review of the pharmacology of anabolic steroids

    Kicman, British Journal of Pharmacology, 2008

    DOI 10.1038/bjp.2008.165 PMID 18500378
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. Binding of anabolic steroids to the androgen receptor and SHBG

    Saartok et al., Endocrinology, 1984

    DOI 10.1210/endo-114-6-2100 PMID 6539197
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Mesterolone against placebo in male infertility

    Gerris et al., Fertility and Sterility, 1991

    DOI 10.1016/s0015-0282(16)54193-4 PMID 1900485
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Mesterolone against vitamin C in male infertility

    Hargreave et al. (Scottish Infertility Group), British Journal of Urology, 1984

    DOI 10.1111/j.1464-410x.1984.tb06160.x PMID 6398725
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. Testosterone undecanoate against mesterolone in hypogonadism

    Luisi und Franchi, Journal of Endocrinological Investigation, 1980

    DOI 10.1007/BF03348281 PMID 7000879
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  6. Mesterolone and blood clotting: case and study in healthy men

    Lowe et al., British Journal of Clinical Pharmacology, 1979

    DOI 10.1111/j.1365-2125.1979.tb00905.x PMID 760733
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  7. Case report: liver injury from mesterolone

    Pérez Palacios et al., Gastroenterología y Hepatología, 2019

    DOI 10.1016/j.gastrohep.2019.06.001 PMID 31405534
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Search on ClinicalTrials.gov (no trial with mesterolone)

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Approval status and ATC code in ChEMBL

    ChEMBL, EMBL-EBI (CHEMBL258918)

    Checked 26 Oct 2026 via ChEMBL
  2. Structure of mesterolone in PubChem

    PubChem, U.S. National Library of Medicine (CID 15020)

    Checked 26 Oct 2026 via PubChem

In the shop

Proviron (Mesterolone) in the catalog

Sizes, prices and shipping times are on the product page.

To the product