Ostarine (MK-2866 / enobosarm)
Muscle & Strength · SARM
Tier C+
Bottom line
Read Off Label grades Ostarine (MK-2866 / enobosarm) as C+ (5.5/10) based on moderate evidence, med benefit magnitude, and a med-risk safety profile.
Most studied SARM clinically.
Typical use: Typical illicit: 10-25 mg/day PO for 8-12 weeks — NOT FDA-approved; sold as 'research chemical' (gray market); repeated SARMs Control Act bills (2018/2019/2025) have not passed — still not federally scheduled; banned sport.
What this is
Most studied SARM clinically. Veru ARES Ph3 in AR+/ER+ breast cancer (2024). FDA has warned against SARMs in supplements multiple times. 2025 Grassley/Whitehouse SARMs Control Act bill introduced again; previous versions (2018, 2019) did not pass. Despite marketing, not 'side-effect-free' vs steroids. Veru has pivoted enobosarm to preserving lean mass during GLP-1 (semaglutide) weight loss - Phase 2b QUALITY in older adults; FDA alignment reached Sept 2025 for enobosarm + GLP-1 RA in obesity. The earlier muscle-wasting/cachexia program was discontinued (improved lean mass but not strength), making the 'keep the muscle on GLP-1' use its most credible clinical path.
Mechanism
Selective androgen receptor modulator; tissue-selective AR agonist (muscle/bone agonist, lesser prostate activity); developed by GTx for muscle wasting and now Veru for breast cancer (ARES trial)
Dose & route
Typical illicit: 10-25 mg/day PO for 8-12 weeks
Citations
- https://pubmed.ncbi.nlm.nih.gov/21798027/
- https://www.fda.gov/consumers/consumer-updates/fda-warns-against-using-sarms-bodybuilding-products
- https://www.supplysidesj.com/supplement-regulations/senators-introduce-bill-to-make-sarms-controlled-substances
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Common questions
- Does Ostarine (MK-2866 / enobosarm) work?
- Read Off Label rates the evidence for Ostarine (MK-2866 / enobosarm) as Moderate and the benefit magnitude as med, producing an overall grade of C+ (5.5/10). Most studied SARM clinically.
- Is Ostarine (MK-2866 / enobosarm) safe?
- Ostarine (MK-2866 / enobosarm) has a med risk profile in published human data. Legal status: NOT FDA-approved; sold as 'research chemical' (gray market); repeated SARMs Control Act bills (2018/2019/2025) have not passed — still not federally scheduled; banned sport (WADA). This is not medical advice — see the disclaimer.
- What is the typical dose for Ostarine (MK-2866 / enobosarm)?
- Typical illicit: 10-25 mg/day PO for 8-12 weeks
- How does Ostarine (MK-2866 / enobosarm) work?
- Selective androgen receptor modulator; tissue-selective AR agonist (muscle/bone agonist, lesser prostate activity); developed by GTx for muscle wasting and now Veru for breast cancer (ARES trial)
This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.