Cardarine (GW-501516)
Also known as: gw-501516, endurobol
Sold alongside SARMs but not one: a metabolic drug abandoned in development after animal studies found cancer across multiple organs.
Legal status: UK: unlicensed, not a licensed medicine; sale for human consumption is unlawful. Not approved for any performance use. Checked 2026-07-26.
Prohibited in sport: Yes — on the WADA Prohibited List.
What it is
Cardarine is a PPARδ agonist, a metabolic modulator, not an androgen and not a SARM despite being sold as one. It was developed as a treatment for dyslipidaemia and metabolic disease, and its development was terminated.
What’s claimed
- Dramatic increases in endurance: the 'exercise in a pill'
- Fat loss without muscle loss
- No hormonal side effects because it is not an androgen
What the evidence shows
The endurance effect is documented in mice, and it is genuinely striking in that setting, which is where the marketing story comes from. It has never been demonstrated in humans (Not supported, on animal basis). The reason it was never tested further is the decisive fact: long-term rodent carcinogenicity studies found tumours developing across multiple organ systems, and development was halted on those grounds. WADA issued an unusual explicit warning to athletes about the health risk, separate from its prohibited-list entry.
The risks
- Carcinogenicity: rodent studies found tumours across multiple organ systems at a range of exposures, which is why development stopped. No human safety data exist to set against this.
- Unknown human profile: with no completed human trials, there is no characterised side-effect profile at all; the absence of reported harms is absence of data, not evidence of safety.
- Product risk: manufactured outside any regulatory system. Independent testing repeatedly finds these products mislabelled, under- or over-concentrated, or containing entirely different active drugs, so the real exposure is unknowable from the label.
What needs monitoring
- There is no established monitoring protocol, because there is no established use. Anyone who has taken it should tell their doctor rather than manage it alone.