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Nonsteroidal selective androgen receptor modulator · Fact sheet

Enobosarm

Also known as Ostarine · GTx-024 · MK-2866 · S-22

Enobosarm, also called ostarine, is an investigational SARM with human muscle-wasting and cancer studies. Some trials increased lean mass, but this does not establish safe bodybuilding or an approved muscle-enhancement regimen.

Not FDA approvedEarly human evidence
Muscle & recoveryHormones & sexual health

What is Enobosarm?

SARMs are selective androgen receptor modulators. Selective describes a development goal, not absence of systemic androgenic or metabolic effects.

Enobosarm is a small molecule and not a peptide, dietary nutrient or approved testosterone product.

Benefits & claims

Interest includes performance or metabolic effects, but a mechanism, hormone change or lean-mass result does not establish safe improvement in athletic function.

What the evidence supports

  • The older-adult study found dose-related lean-mass increases and a selected functional benefit.
  • The cancer study involved a defined wasting population and an evaluable-subset analysis.
  • These studies cannot establish favorable long-term risk or athletic benefit in healthy young users.
Research areas
  • Performance-related biology
  • Clinical or preclinical disease research

Dosage & frequency

Human study context

This is an exposure from a named human study, not a generally established treatment or enhancement regimen.

Cancer-wasting enobosarm phase 2 trial

Men older than 45 and postmenopausal women with selected cancers and recent weight loss

Amount
1 or 3 mg in separate treatment groups
Frequency
Once daily for up to 113 days
Route studied or labeled
Oral

This is oncology research, not a bodybuilding schedule. Efficacy was analyzed in a reduced evaluable subset, and the study does not establish long-term safety.

Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial.
How to read these amounts

An approved regimen belongs to a specific product, indication, and population. A study regimen describes what researchers tested; it does not establish a prescription or a safe self-use protocol. Products, routes, and formulations are not interchangeable. A prescriber uses the full label and individual clinical circumstances.

Personal accounts may describe amounts, schedules and outcomes beyond clinical research. They do not establish a regimen. Read the reported experiences

Formulations, interactions & practical context

Formulation differences

  • Enobosarm is a small molecule and not a peptide, dietary nutrient or approved testosterone product.

Interactions & precautions

  • The reviewed sources do not establish a comprehensive human interaction profile for this exact substance or combination.

What is still unresolved

  • Long-term clinically meaningful benefit
  • Endocrine, cardiovascular and organ safety
  • Identity, exposure and interaction differences outside research settings
The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial. Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial. FDA: serious risks of SARM bodybuilding products

Side effects & risks

  • FDA warns that SARM products can be associated with serious liver, cardiovascular and hormone-related harms.
  • Short monitored trials do not establish safety of higher exposure, prolonged use or uncertain products.

This is a summary of the cited evidence, not a complete product label. A lack of human safety data does not establish safety.

Clinical research

Early human evidence

A 120-person older-adult trial found lean-mass and selected functional effects. A cancer trial analyzed efficacy in only 100 of 159 safety participants, limiting generalization.

Studies

Personal experiences

Reports describe what someone noticed. They cannot establish cause, typical results, or how often a side effect happens. Amounts and schedules describe the individual account, not an effective or safe dose. Product identity and strength may be unverified, and missing details are left explicit.

Explore 2 sourced accounts by reported effect.

Appetite: reported experiences

Mixed account · personal report

Physical changes alongside fatigue and large mood swings

Another author described favorable physical changes but less enjoyment, less drive to train or eat, more tiredness and large swings between sadness and anger after three weeks of ostarine.

Reported use in this account

Product
Ostarine (enobosarm)
Amount
25 mg as reported; frequency not specified
Frequency
Not specified clearly
Route
Not specified clearly
Duration
Three weeks

The author called this suppression but had only planned blood testing, so hormone suppression was not established in the account. The post does not verify product composition or an independent cause of the mood symptoms.

Read the original account

Approval status

Enobosarm has no FDA-approved therapeutic product. The cited research does not establish an approved performance-enhancement use.

Phase 2 research; no FDA-approved product

Approval covers the labeled product, use and population. A trial phase does not establish success; a stopped program is not ongoing research.

Open questions

  • Long-term clinically meaningful benefit
  • Endocrine, cardiovascular and organ safety
  • Identity, exposure and interaction differences outside research settings

Summary

These studies cannot establish favorable long-term risk or athletic benefit in healthy young users.

Sources

Medical evidence and regulatory sources are listed here. Personal reports are linked separately in the experiences section.

  3. fdaFDA: serious risks of SARM bodybuilding products

    FDA class-level warning: unapproved products, liver injury and cardiovascular and hormone-associated risks; not a compound-specific incidence estimate.

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