Anabolic steroidAndrogenNon-aromatisingOral17-alpha-alkylatedDesigner steroid

Methylstenbolone

Also known as M-Sten · Methyl-Sten · Methylstenbolone · 2,17α-dimethyl-5α-androsta-1-en-17β-ol-3-one

Written by enwyReviewed 4 Aug 20262 sources0 comments

Methylstenbolone (M-Sten) is a potent 17α-methylated designer steroid, a methylated analogue of stenbolone. Reputed for strong dry mass and strength gains, it is highly hepatotoxic and strongly suppressive, with efficacy and safety data limited to anecdote and case reports.

01 Overview

Methylstenbolone is one of the more potent 'hardcore' prohormones/designer steroids sold in the early 2010s. Structurally it is a 2,17-dimethylated, 17α-alkylated non-aromatising androgen related to stenbolone, giving it a reputation for rapid dry mass and strength with no estrogenic bloat. It is orally active due to methylation.

Because it is 17-alpha-alkylated and often run at effective doses, it is regarded as strongly hepatotoxic, and case reports describe drug-induced liver injury after M-Sten-containing products. There are no controlled human trials; all efficacy claims are anecdotal. It was among the compounds targeted by the 2014 US Designer Anabolic Steroid Control Act.

02 Mechanism

17α-methylated, non-aromatising androgen receptor agonist related to stenbolone; methylation confers oral activity and hepatic strain.

03 Dosing

Tier	Dose	Route	Notes
Common (marketed)	8–16 mg/day	Oral	Low milligram dosing reflects potency; historic 4-6 week runs, higher doses sharply increased liver risk.

Ester comparison

Ester	Half-life	Injection freq.	Testosterone by mass

04 Effects

Effect	Magnitude	Evidence
Rapid dry mass gainUsers report substantial dry lean gains for a prohormone over a short cycle.	reported strong	Anecdotal
Marked strength increaseNotable strength gains commonly reported.	reported strong	Anecdotal

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
HPTA suppressionStrong testosterone suppression requiring PCT.	Severe	Near-universal	Anecdotal
Drug-induced liver injuryCase reports document significant hepatotoxicity, including jaundice and hepatitis, from M-Sten products.	Life-threatening	Common	Observational

06 Legal status

United Kingdom

Class C

Anabolic steroid under the Misuse of Drugs Act. · as of Jan 2026

United States

Schedule III controlled

Covered by the Designer Anabolic Steroid Control Act of 2014. · as of Jan 2026

07 References

Severe hepatotoxicity associated with methylstenbolone-containing supplementsCase reports, hepatology literature

Metabolism of methylstenboloneDrug Testing and Analysis

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.