MK-2866 Reference

Plain English

What it is

MK-2866, also sold under the names Ostarine and Enobosarm, is a SARM, which is a lab-made drug designed to act on the body's muscle-building hormone signals. It is sold as a research chemical, not as an approved medicine.

What people use it for

In the bodybuilding and fitness community, people talk about it for building muscle, losing body fat, and easing joint discomfort. Those goals come from personal reports and online talk, not from any approved use.

What the science shows

It is the most-studied SARM and even reached late-stage human trials for muscle loss in cancer patients, but those trials gave inconsistent results and it was never approved by regulators. There are no completed trials showing it safely improves body shape in healthy people.

The catch

Health agencies warn against SARMs like this one: they are not approved for people, are often sold illegally and mislabeled in supplements, and are banned in sport at all times as anabolic agents. Studies in people report lowered natural testosterone, drops in 'good' HDL cholesterol, and signs of liver strain. The popular 'mild SARM' label oversells how safe it really is.

Reference summary

Most-studied SARM with completed Phase 3 cancer-cachexia trials. Despite trial-level lean-mass improvements, the program did not yield FDA approval. No body-composition trials in healthy adults exist.

Regulatory and posture

Categories

SARM, Recovery

Aliases

Ostarine, Enobosarm, GTx-024, S-22, Non-steroidal SARM

Evidence posture

human - FDA enforcement attention. Sold only as a research chemical, not for human consumption per legal seller terms. WADA-prohibited under category S1.2 at all times. Failed Phase 3 in cancer cachexia (POWER trials) - no FDA approval followed. No human clinical efficacy program for body-composition use.

Regulatory status

No FDA-approved MK-2866 drug label. GTx ran Phase 3 trials (POWER 1 and POWER 2) in non-small-cell lung cancer cachexia; the program failed to meet co-primary endpoints, and FDA approval did not follow. WADA prohibits MK-2866 under category S1.2 anabolic agents at all times. FDA has issued explicit consumer warnings against SARMs in bodybuilding products.

Content review status

research reference

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