SARMs
Ostarine / MK-2866, LGD-4033, LGD-3033, RAD-140, RAD-150, S23, S4 / Andarine, AC-262, YK-11, OTR-AC · Selective androgen receptor modulators
What it is
Investigational drugs designed to stimulate androgen receptors in muscle and bone while sparing other tissues — the pharmaceutical goal was steroid benefits without steroid side effects. None has completed development; several were abandoned mid-trial.
What human evidence shows
Early-phase human trials (ostarine, LGD-4033) show real but MODEST lean-mass gains — a few pounds over weeks, far below what steroid trials show. The "selective" promise is only partially borne out: testosterone suppression appears in trials at higher doses. Development stalled largely because effects didn't justify risks to sponsors.
Risks
Documented in trials and case reports: dose-dependent natural testosterone suppression, adverse lipid shifts, and a growing case-report literature of drug-induced liver injury. The bigger practical risk: JAMA analyses found most products sold as "SARMs" online are mislabeled — wrong compound, wrong dose, or containing actual steroids. You cannot know what you bought.
Legal status
US: not approved for human use; sale for consumption is illegal (FDA warning letters are routine), though widely sold as "research chemicals". WADA-banned. Military drug tests screen for them.
Evidence base
established literature
Strong human evidence: either a phase 3 or 4 trial report alongside review-level evidence, or ten or more randomised controlled trial reports.
- phase 3/4
- 0
- randomised
- 10
- reviews
- 6
- human trials
- 13
Counts are of published papers, not distinct trials, and measure how much research exists — not whether this works or is safe for you.
Research (12)
- SarcopeniaJoint Bone Spine · 2019
- Testosterone Replacement Therapy in Hypogonadal MenEndocrinol Metab Clin North Am · 2022
- Current and investigational medications for the treatment of sarcopeniaMetabolism · 2023
- Selective Androgen Receptor Modulators2012
- Sarcopenia and osteoporosisGerontology · 2025
- Selective Androgen Receptor Modulators-Transformative Drugs or Heralds of the Next Drug Epidemic?JAMA · 2024
- Selective androgen receptor modulators: a critical appraisalFront Endocrinol (Lausanne) · 2025
- Development of selective androgen receptor modulators (SARMs)Mol Cell Endocrinol · 2018
- Selective Androgen Receptor Modulators: An Emerging Liver ToxinJ Clin Transl Hepatol · 2023
- The androgen receptorVitam Horm · 2023
- Novel androgen therapies including selective androgen receptor modulatorsBest Pract Res Clin Endocrinol Metab · 2022
- Selective Androgen Receptor Modulators: Current Knowledge and Clinical ApplicationsSex Med Rev · 2019
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