Gestrinone: the safety data is all from women, and almost nobody using it now is one

The short version. Gestrinone is not approved in the United States or Canada. It is a 19-nortestosterone derivative, so a steroid rather than a peptide, and it was not part of the July 2026 advisory committee vote. There is a real safety literature, and it describes 3,745 women treated for endometriosis and related conditions. That is not the population asking about it now.

Why the safety numbers you have read do not describe you

This is the whole story, so it goes first. A systematic review published in Pharmaceutics in May 2025 pulled together 33 articles covering 32 unique studies and 3,745 women. More than half of those studies, 53.12 per cent, were about endometriosis. The rest covered contraception, uterine fibroids and mastalgia.

Those are the numbers that get quoted in forums and in clinic marketing as evidence that the compound is well tolerated. They may well be, in women, at therapeutic doses, for a gynaecological condition. The use that drives most of the current interest is different in every one of those three respects: a different population, a different purpose, and often a different route, since the aesthetic use is frequently by subcutaneous implant.

Nothing about that makes the research wrong. It makes it the wrong research to be reassured by. A safety profile is not a property of a molecule. It is a property of a molecule, a dose, a route and a person.

What the literature actually recorded

In that population, these were the most frequently documented effects. The rates below are exactly as the review reports them, and the denominators differ between rows because the review reports some as a share of cases and others as a share of reports.

How strong is that evidence

Weaker than its frequent citation suggests. The reviewers assessed risk of bias formally, using RoB 2.0 for the randomised studies and ROBINS-I for the rest. They rated 68.25 per cent of the randomised studies at high risk of bias, with the remaining 31.75 per cent raising some concerns. Among the non-randomised studies, 56.25 per cent were moderate, 40.63 per cent severe and 3.13 per cent critical.

Not one category came out clean. Their own conclusion was that the evidence remains insufficient to fully understand the risks associated with widespread unregulated use, and that standardised studies and regulatory oversight are needed.

Where it stands legally and in sport

In the United States and Canada, it has never been approved for anything. In Europe, Australia and parts of Latin America it is a marketed medicine for endometriosis. Those two facts are often blurred into a claim that it is approved somewhere so it must be fine, which skips the part where the approval is for a different indication in a different population.

In sport the position is unambiguous. Gestrinone sits in WADA category S1.1, anabolic androgenic steroids, prohibited at all times, in and out of competition. Substances in S1 are non-Specified Substances, a classification that matters because of how it changes the handling of an anti-doping case.

It was not in the July 2026 vote, and this matters

The advisory committee that met on 23 and 24 July 2026 reviewed seven substances: BPC-157, KPV, TB-500, MOTS-c, emideltide, Semax and Epitalon. All peptides. Gestrinone was not among them.

We spell this out because the two subjects travel together online, through the same vendors and the same communities, and a lot of people have come away believing that something changed in July that applies here. Nothing did. Its position on 5 October 2026 is exactly what it was in June. For what did move that week, and by what margin, see the status tracker.

The one number that is yours

Of everything in the review, the figure most worth sitting with is raised transaminases in 15.1 per cent of reports. That is a liver signal, it appeared in women on therapeutic doses under medical supervision, and unlike almost everything else in this subject it is measurable in an afternoon.

We do not tell anyone what to take or not take. We would say that a number you can measure is worth more than a consensus you cannot check, and that this one has a name and a reference range.

What is still unknown

• What it does in men. The safety literature is in women.
• What happens at the doses actually used for physique. Not studied.
• What the implant route changes. The review covers the studied uses, not the subcutaneous implants used aesthetically.
• Long-term exposure. The authors said plainly that the evidence is insufficient to understand the risks of widespread unregulated use.
• What is in unregulated product. Nothing sold outside a licensed supply chain carries an assurance of identity or purity.

How to read any other page about this compound

One question sorts most of them. When a page cites a tolerability figure, does it say who was studied? If it gives you 42.7 per cent for acne without mentioning that the studies were in women being treated for endometriosis, it is not reporting the evidence, it is borrowing its authority.

This page carries a date at the top so you can tell when it stops being current.

The questions people actually type

Sources