MK-2866 (Ostarine) (Ostarine / Enobosarm (MK-2866))
One of the most widely discussed selective androgen receptor modulators (SARMs). Studied for preserving and building lean muscle with fewer androgenic side effects than anabolic steroids. It is not an approved drug and is banned by WADA.
How it works
Selectively binds androgen receptors in muscle and bone tissue, stimulating anabolic (muscle-building) signaling while having relatively less effect on the prostate and other androgen-sensitive tissues than testosterone.
Key facts
- Molecular weight: 389.33 Da
- Half-life: ~24 hours
- Bioavailability: Oral
- Storage: Keep cool, dry, and sealed; protect from light.
Dosing overview
- Typical dose: Commonly cited 10-25 mg/day (research)
- Frequency: Once daily
- Duration: Commonly cited 8-12 week cycles
- Route: Oral
Protocol notes
- Once-daily oral dosing is typical due to the ~24h half-life.
- Users commonly run 8-12 week cycles followed by a break/PCT, since it can suppress natural testosterone.
- Bloodwork (lipids, testosterone, liver markers) is strongly advised given suppression risk.
Reported benefits
- Lean muscle preservation/gain
- Bone density support (research)
- Less androgenic than steroids
- Studied for muscle wasting
Possible side effects
- Testosterone suppression
- Lowered HDL cholesterol
- Possible liver enzyme elevation
- Fatigue/mood changes during/after a cycle
Research
- Enobosarm in muscle wasting (2013): Increased lean body mass and improved physical function in cancer-related muscle wasting trials.
Community reviews of MK-2866 (Ostarine)
- dose_diary_alex rated it 5/5 - Noticed clear benefits within weeks: Added MK-2866 (Ostarine) to my protocol about 2 months ago and it has earned its place. The benefits became noticeable around week 2-3 and have been consistent since. What I appreciate about this compound is the predictability. It does what the research suggests it should do, at roughly the timeline you would expect. No surprises, no dramatic swings, just steady improvement. No notable side effects to report at my dose. Sourcing is always the challenge with research compounds, insist on third-party testing. Storage and reconstitution per standard protocols. Plan to continue.
- dose_diary_alex rated it 5/5 - Worth adding to the protocol: MK-2866 (Ostarine) has been a worthwhile addition. I am data-driven and tracked relevant markers before, during, and after. The improvement is measurable and correlates with the intervention timeline. What sets this apart from some compounds I have tried is the consistency. Benefits did not fluctuate wildly or disappear. They built up and maintained. That gives me confidence in the mechanism. Tolerance has been excellent. Nothing in my bloodwork or subjective experience raised any flags. This is the kind of compound that does its job quietly without causing problems. Exactly what you want.
- peptide_path_pam rated it 5/5 - Genuinely effective after 2 months: Been using MK-2866 (Ostarine) for about 2 months and the results are clear. Not overnight dramatic, but a steady, consistent improvement that became undeniable by the end of the first month. The mechanism makes sense based on what I have read in the literature, and my subjective experience matches the expected timeline. Benefits built gradually and plateaued at a good level. Side effects were minimal to none at the dose I used. Followed proper protocols for sourcing, storage, and administration. Would recommend to others who have done their research and have realistic expectations.
Compare MK-2866 (Ostarine)
Research and educational reference only. Not medical advice.