Methyl-1-testosterone (M1T)

What methyl-1-testosterone is

M1T (17β-hydroxy-17α-methyl-5α-androst-1-en-3-one) is the 17α-methylated form of 1-testosterone, a derivative of dihydrotestosterone with a double bond in the A ring. It was never developed or approved as a medicine. It became known as an ingredient of products sold as dietary supplements for muscle building; experts call labels such as “prohormone” misleading for such steroids.

With the Anabolic Steroid Control Act of 2004, the US added M1T by name to the legal definition of anabolic steroids. This places it in the same group of designer steroids as methasterone, only regulated earlier.

How it works

The key pharmacological investigation dates from 2011. In the yeast assay, M1T strongly activated the androgen receptor. In rats, injected under the skin, it increased in a dose-dependent manner the weight of the pelvic floor muscle, a measure of the anabolic effect, and of the prostate, a measure of the androgenic effect. Swallowed, it did not change these organ weights, but it stimulated cell division in the prostate, altered IGF-1 and the androgen receptor in the calf muscle, and had a particularly strong effect on the liver.

The authors conclude that M1T is a potent androgen and anabolic agent, without the tissue selectivity hoped for from SARMs, and could damage the liver, especially as a tablet. The 17α-methyl group makes a steroid work when swallowed, and it is precisely the feature most closely associated with cholestasis, peliosis hepatis and liver tumors.

What the studies show

Parr 2011: cell assay, rat and urine

The researchers identified M1T in products sold as dietary supplements and tested it in three ways: in the yeast assay for activation of the androgen receptor, in the Hershberger assay in rats for anabolic and androgenic effects, and in urine for metabolites. M1T proved to be a potent androgen and anabolic agent, both injected under the skin and swallowed. In human urine, several metabolites were found alongside M1T, and their excretion was followed over time. The paper contains no investigation of muscle, strength or side effects in humans.

Al-Niaimi 2013: kidney injury

A patient with severe atopic dermatitis was being treated with ciclosporin, a drug that dampens the immune system. He also took M1T and developed acute kidney injury. The authors attribute it to an interaction that alters the breakdown of ciclosporin and advise physicians to ask about “supplements” bought over the counter.

Robles-Diaz 2015: liver injury from anabolic steroids

The paper analyzes 25 cases of liver injury from anabolic steroids from Spanish and Latin American registries, not specifically from M1T. In the Spanish registry, their share of all reported drug-induced liver injuries rose from under 1 percent (2001 to 2009) to 8 percent (2010 to 2013). Those affected were mostly young men, on average 32 years old, with jaundice and hospitalization; with pronounced cholestasis, kidney damage also occurred. There were no deaths in this analysis.

Rahnema 2015: designer steroids in supplements

The review describes how designer steroids remained available in over-the-counter products despite bans on individual substances. Reported are liver damage, cholestasis, kidney failure, testicular hypofunction, breast growth in men and infertility. Some effects regress, others do not.

Where the data stop

• No study in humans. There is no clinical study on muscle mass, strength or performance. The effect is inferred from cell experiments and rats, not measured.
• Liver risk from animals and the drug class. For M1T there are no systematic human data on the liver, only the animal findings and experience with related 17α-methylated steroids, see oxandrolone.
• Hormone axis, heart and blood lipids not studied. Data for M1T are lacking; the findings on steroids in general are under anabolic steroids.
• Origin of the products. There has never been an approved product. What is traded comes from the gray market and has not been tested in any human study.

Status, approval and legal

M1T has never been approved as a medicine, neither in Germany nor in the EU or the US. In Germany, finished medicinal products may only be placed on the market with an approval (§ 21 German Medicines Act). Methyl-1-testosterone is listed by name in the annex of the German Anti-Doping Act: manufacturing, trading, supplying and prescribing for doping in sport are prohibited, as are acquiring, possessing and bringing into the country non-small quantities for doping; violations are punishable.

In the US, the Anabolic Steroid Control Act, signed on October 22, 2004 and in force 90 days later, added M1T by name to the definition of anabolic steroids in the Controlled Substances Act; selling it as a dietary supplement has not been legal since then. In sport, M1T is listed by name on the WADA Prohibited List 2026 under S1.1 and is banned at all times.

Safety

Liver: in rats, M1T had a strong effect on the liver, especially when swallowed. As a 17α-methylated steroid, it belongs to the group most closely associated with cholestasis, peliosis hepatis, that is, blood-filled cavities in the liver, and liver tumors. Liver injury from anabolic steroids often presents with severe jaundice, and with pronounced cholestasis also with kidney damage. Kidney: one case report of acute kidney injury due to an interaction with ciclosporin. For hormones, heart and blood lipids there are no data specific to M1T; for designer steroids as a whole, testicular hypofunction, breast growth in men and infertility have been described.

Because there is no human study, it is also unknown at what point and how often these harms occur with M1T. A low number in the BK-Score here means: barely studied, not harmless.

Sources

• Parr MK et al., Endocrinology 2011 – methyl-1-testosterone: anabolic and androgenic potency, side effects and metabolism (cell assay, rat, human urine)
• Al-Niaimi F, Lyon CC, Dermatol Ther (Heidelb) 2013 – acute kidney injury due to interaction of M1T with ciclosporin, case report
• Joseph JF, Parr MK, Curr Neuropharmacol 2015 – synthetic androgens as designer supplements
• Rahnema CD et al., Andrology 2015 – designer steroids in over-the-counter supplements, review
• Robles-Diaz M et al., Aliment Pharmacol Ther 2015 – liver injury from anabolic steroids in Spanish and Latin American registries, 25 cases
• LiverTox (NIH) – Androgenic Steroids: liver injury from 17α-alkylated steroids
• Anabolic Steroid Control Act of 2004, Public Law 108-358 – 17-α-methyl-1-testosterone classified as an anabolic steroid
• German Medicines Act (AMG), § 21 marketing authorization requirement
• German Anti-Doping Act (AntiDopG), annex – anabolic-androgenic steroids (methyl-1-testosterone)
• NADA – Prohibited List 2026, informative German translation (S1.1 anabolic-androgenic steroids)