Methylstenbolone

What methylstenbolone is and how it works

Methylstenbolone has the chemical name 2α,17α-dimethyl-17β-hydroxy-5α-androst-1-en-3-one. It has the same two methyl groups as methasterone, plus a double bond between carbon 1 and 2. It was never developed as a medicine; a review lists it as a designer steroid that was never approved for medical use and is used as an illegal dietary supplement (Tauchen 2021). In 2013 a doping laboratory described a product bought online that contained methylstenbolone, as stated on the label (Cavalcanti 2013).

How it works can only be inferred from its structure: steroids of this kind bind to the androgen receptor, have anabolic and masculinizing effects and suppress the body’s own hormone production. None of these effects has been measured for methylstenbolone itself. Products that contained methasterone and dimethazine in addition to methylstenbolone had a strongly androgenic effect in cell experiments, lasting several days (Tran 2023). The methyl group in the 17α position makes the substance effective as a capsule and slows its breakdown in the liver. For an overview of the substance group, see Anabolic steroids (AAS).

What the studies show

Excretion in 4 volunteers

Cavalcanti 2013 gave 4 volunteers a single dose and analyzed their urine. Unchanged methylstenbolone was detectable for only about 45 hours, two metabolites for more than a week. The study makes no statement about efficacy.

Long-term detection with a labeled substance

Piper 2019 used methylstenbolone labeled with heavy hydrogen so that even small amounts could be reliably attributed. After a single dose, urine was collected for 29 days. Up to 40 metabolites were found; three of them were still detectable on the last day of the study. The study served to extend the detection window in doping controls.

Case report: jaundice after 30 days

Agbenyefia 2014 describes a previously healthy 26-year-old man who had taken the product “Super DMZ Rx 2.0”, containing methylstenbolone and dimethazine, for 30 days according to the manufacturer’s instructions and developed jaundice due to bile stasis. The authors call it the first reported case involving this product.

Complaints caused by contaminated vitamin products

In New York in 2012 and 2013, around 16 people reported nonspecific complaints such as fatigue, hair loss and muscle pain. What they had in common was a vitamin B and mineral product from the same supplier. The analysis found methasterone, dimethazine and methylstenbolone. One patient was hospitalized with liver damage, and a child showed marked virilization (Tran 2023). What share of the complaints was due to methylstenbolone cannot be separated out.

Where the data stop

There is no study comparing methylstenbolone with placebo, neither on muscles and strength nor on the liver, blood lipids or hormones. Experts on designer steroids describe exactly this pattern: little is known about the effects and metabolism of unapproved steroids because clinical studies are lacking (Joseph and Parr 2015).

The case reports are limited as well. In both documented cases other steroids were involved, dimethazine or methasterone, and the amounts in the products were not controlled. How common liver damage is under methylstenbolone cannot be read from them.

Status, approval and legal

Methylstenbolone is not approved as a medicine in Germany, the EU or the US. In Germany it is listed by name in the annex of the Anti-Doping Act: manufacturing, trading and placing it on the market for doping purposes are prohibited, as are acquiring, possessing and bringing it into the country in non-small quantities for doping in sport (§ 2, punishable under § 4). It is not listed by name on the 2026 WADA Prohibited List, but falls under S1.1 as a substance with a similar chemical structure and is therefore banned at all times.

Safety

In humans, only individual cases are documented: jaundice due to bile stasis after a product containing methylstenbolone and dimethazine (Agbenyefia 2014), and a cluster of complaints with one case of liver damage and virilization in a child after contaminated vitamin products (Tran 2023). A review of designer steroids in supplements lists liver damage, bile stasis, kidney failure, testicular underfunction, breast growth in men and infertility for the group; some of this is reversible, but with aggressive use damage can persist (Rahnema 2015). That a product labeled methylstenbolone also contained methasterone (Geldof 2014) points to a further risk: with such goods, what is actually inside is an open question. For the class risks of anabolic steroids, see Anabolic steroids (AAS).

Sources

• Agbenyefia P et al., J Investig Med High Impact Case Rep 2014 – jaundice due to bile stasis after methylstenbolone and dimethazine, case report
• Tran BN et al., Steroids 2023 – methasterone, dimethazine and methylstenbolone in vitamin and mineral products, health harms in New York
• Cavalcanti GA et al., Steroids 2013 – methylstenbolone in a “dietary supplement”, excretion in 4 volunteers
• Piper T et al., Drug Test Anal 2019 – metabolism of methylstenbolone in humans and long-term detection
• Geldof L et al., Biomed Chromatogr 2014 – metabolism of methylstenbolone; product additionally contained methasterone
• Rahnema CD et al., Andrology 2015 – designer steroids in over-the-counter supplements, review
• Joseph JF, Parr MK, Curr Neuropharmacol 2015 – synthetic androgens as designer supplements
• Tauchen J et al., Molecules 2021 – medical use of testosterone and related steroids, review including designer steroids
• German Anti-Doping Act (AntiDopG), § 2, § 4 and annex
• NADA – 2026 Prohibited List, informational German translation (S1.1 anabolic androgenic steroids)