YK-11 is a synthetic steroid, first described by researchers in Japan, that acts as a partial activator of the androgen receptor and is described as a selective androgen receptor modulator (SARM). Unlike most SARMs it has a steroid structure. It has been studied only in cells and animals and is not approved for human use.
Also known as: YK11.
For YK-11, there is no approved product and no published human trial, so there are no label strengths or studied human amounts.
YK-11 is not FDA approved, and we could not find any published trial that gave it to people. It is sold as a SARM; fDA says SARMs are unapproved drugs that cannot be legally marketed in the US as dietary supplements or drugs, and lists risks including liver injury and acute liver failure, a higher risk of heart attack or stroke, and effects on fertility. The World Anti-Doping Agency (WADA) names it on its 2026 Prohibited List as a SARM under "other anabolic agents" (S1.2), banned in and out of competition.
In cell studies, YK-11 partly switched on the androgen receptor (Kanno 2011), and in mouse muscle cells it drove muscle-cell development by raising follistatin, a protein that blocks myostatin (Kanno 2013). In a rat study (Dahleh 2023), five weeks of YK-11 increased oxidative stress and harmed mitochondria in the hippocampus, a memory area of the brain. Cell and rat results often do not carry over to people.
An anti-doping lab found YK-11 in a black-market product and ran an excretion study (Piper 2018): no intact YK-11 showed up in urine, but its breakdown products were traceable for more than 48 hours.
We could not find a published human half-life or time to peak, so we do not list one. Figures quoted online usually come from animal studies.
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