Primary entity: OstarineAlso known as: Enobosarm; MK-2866; MK2866; GTx-024; S-22Class: performance-adjacent literacy (see page)Cluster: Performance-adjacent
Ostarine is the common name for enobosarm (MK-2866 / GTx-024), one of the more clinically studied selective androgen receptor modulators historically explored for muscle wasting and oncology-adjacent indications. It is not a peptide, is not FDA-approved as a consumer physique medicine, and is explicitly named (enobosarm / ostarine) among SARMs on the WADA Prohibited List. “Milder than steroids” marketing is not a safety guarantee.
Ostarine/enobosarm is not a peptide. It is a nonsteroidal SARM. MK-2866 is a SARM code — do not confuse with MK-677 (ibutamoren), which is a GH secretagogue, not a SARM.
Not FDA-approved for bodybuilding or general muscle-building consumer use. Developmental oncology/muscle programs have not produced an approved physique label. WADA: enobosarm (ostarine) under S1.2. Contaminated supplements remain a documented inadvertent-positive theme in anti-doping education.
Key takeaways
- Not a peptide — SARM enobosarm (MK-2866).
- ≠ MK-677 — different drug class entirely.
- Not FDA-approved for recreational muscle building.
- WADA-prohibited; supplement contamination risk is real.
- No “beginner SARM cycle” charts on this site.
Questions this page answers
Next questions we answer on this page (curiosity / AI-gap map):
- What is ostarine?
- Aliases / MK codes
- Classification
- What it is NOT
- Mechanism
- Evidence ladder
- What has been studied
- Safety literacy
- Regulatory & WADA
- Why no dosages
- Related
- Who for / not for
Who is this profile for — and who is it not for?
For: readers hitting “mild SARM” marketing who need class, MK-code, and sport literacy.
Not for: beginner-cycle seekers.
What is ostarine?
Enobosarm (ostarine, MK-2866) is a nonsteroidal SARM with a comparatively large public clinical footprint versus many research-only SARMs. That footprint is why forums call it “mild” or “beginner” — clinical study ≠ approved safe consumer drug, and anti-doping risk remains high.
| Chemistry class | Nonsteroidal SARM (enobosarm) |
|---|---|
| Peptide? | No |
| Codes | MK-2866 · GTx-024 · S-22 |
| ≠ MK-677 | Different class (see MK-677 page) |
| Sport | WADA S1.2 |
Also known as
- Ostarine — common name.
- Enobosarm — INN-style name used in clinical/anti-doping materials.
- MK-2866 / GTx-024 / S-22 — codes.
- Confusion trap: MK-677 (ibutamoren) — not ostarine.
Shared “MK-” prefix is coincidence of research coding culture. MK-2866 = SARM (ostarine). MK-677 = ghrelin-mimetic GH secretagogue. See MK-677.
How is ostarine classified?
Investigational SARM with substantial clinical-trial history relative to peers — still unapproved for physique use; WADA anabolic agent.
What is ostarine not?
| Ostarine is not… | Why that matters |
|---|---|
| A peptide | SARM |
| MK-677 / ibutamoren | Different receptor class |
| FDA-approved bodybuilding drug | No such label |
| Risk-free “beginner cycle” | Marketing myth |
| Something we dose | Refusal |
How is ostarine thought to work?
Selective androgen-receptor modulation with tissue-selective anabolic intent — core SARM design.
What human vs animal vs label evidence exists?
| Evidence type | What exists (summary) | Maturity |
|---|---|---|
| Human clinical | Multiple clinical studies in muscle-wasting / oncology-adjacent contexts historically | Human Incomplete development |
| Approved physique label | None | None |
| Anti-doping positives | Frequent SARM analyte in testing — educational theme | Human Sport |
| Forum “mild cycle” claims | Anecdote | None |
Do not paste trial % into evergreen bullets without locked citations.
What has ostarine been studied for?
Muscle wasting, physical function, and oncology-related AR programs historically. Recreational hypertrophy remains offline folklore relative to labels.
What safety topics come up?
Suppression of endogenous testosterone, lipid changes, liver-injury reports in recreational SARM use, and supplement mislabeling/contamination leading to inadvertent positives. Not medical advice.
What is ostarine's regulatory status?
- U.S.: Not approved for consumer muscle building. Developmental programs ≠ OTC.
- WADA: enobosarm (ostarine) under S1.2
- Supplements: FDA warns against SARMs sold as supplements; athletes should assume high contamination risk in “prohormone / natural” products claiming related effects.
Why doesn't this page include a dosage chart?
“Ostarine beginner dosage” is a protocol query we refuse.
Related lab literacy
Not peptide reconstitution. What are peptides?.
Related compounds and comparisons
Frequently asked questions
Is ostarine a peptide?
No. It is the SARM enobosarm (MK-2866).
Is ostarine the same as MK-677?
No. MK-677 is ibutamoren, a GH secretagogue.
Is ostarine FDA approved?
Not as an approved consumer physique medicine.
Is ostarine WADA banned?
Yes under S1.2 SARMs.
Why do people call it mild?
Relative clinical familiarity and marketing — not a regulatory safety rating.
Not a peptide, ≠ MK-677, WADA-relevant, not medical advice. Disclaimer..
Sources
The sources below were checked against PubMed, DailyMed, or the official agency page on November 10, 2026 (America/Phoenix). Links go to the publisher, PubMed, or the agency record.
- Primary — human Dobs AS, Boccia RV, Croot CC, et al. Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial. Lancet Oncol. 2013. doi:10.1016/S1470-2045(13)70055-X. PMID: 23499390. Enobosarm (ostarine) is not an FDA-approved consumer muscle or supplement drug.
- Safety Leciejewska N, Jędrejko K, Gómez-Renaud VM, et al. Selective androgen receptor modulator use and related adverse events including drug-induced liver injury: Analysis of suspected cases. Eur J Clin Pharmacol. 2024. doi:10.1007/s00228-023-03592-3. PMID: 38059982.
- Regulatory U.S. Food and Drug Administration. FDA Warns of Use of Selective Androgen Receptor Modulators (SARMs) Among Teens, Young Adults. Accessed November 10, 2026.
- Anti-doping World Anti-Doping Agency. The World Anti-Doping Code International Standard Prohibited List 2026. Accessed November 10, 2026. Confirm the current list and GlobalDRO before relying on sport status. The 2026 list names enobosarm (ostarine) as a SARM example under S1.2.
- Written by
- Peptide Tutorials Staff — a group of independent researchers & writers (not clinicians)
- Published · Updated
- Oct 7, 2026 · Oct 7, 2026 · Regulatory and sport-status wording checked November 10, 2026 against current FDA labels and the 2026 WADA Prohibited List · How we source & update
Educational disclaimer: Educational only. Ostarine (enobosarm) is not a peptide and is not FDA-approved for physique use. No dosing or buy links. We don't sell peptides. Read our full disclaimers.