What is YK11?
YK11 has a steroid backbone and acts as a partial activator of the androgen receptor. In cell cultures it increased follistatin production, which is why it is advertised as a “myostatin inhibitor”.
How well studied is YK11?
Only cell culture and metabolism studies (including for doping analysis); no clinical studies in humans. Claims about effects and safety in humans are therefore unsupported.
What side effects and risks does YK11 have?
No reliable safety data. Because it acts on the androgen receptor, suppression of the hormone axis, unfavourable blood lipids and liver strain can be expected, as with steroids and other SARMs. Quality and content of online products are entirely unclear.
Is YK11 approved in Germany?
In short: no. Not approved anywhere and never clinically developed. WADA: S1.2, listed by name, prohibited at all times; already detected in doping samples. As an anabolic agent under the WADA list it is also relevant for athletes under the AntiDopG (self-doping).
Sources
- Kanno et al.: YK11 regulates myogenic differentiation via follistatin (PubMed 23995658)
- WADA Prohibited List 2025 (International Standard)
Note: We deliberately do not list any doses here. For approved medicines, your doctor sets the dose; for unapproved substances there is no reliable information.