• First described in 2011.
  • This SARM differs from the other SARMs because it uses an anabolic androgenic steroid backbone but is unique in comparison to Anabolic steroids. Other SARMs are non-steroidal in nature.
  • It only partially activates Androgen Receptors (ARs).
  • Even classification as a SARM is contended by many because of the fact that it increases release of Follistatin (An enzyme that inhibits myostatin which is an enzyme responsible for limiting how muscle much an individual can have on their body).
  • It is still in early stages of development and thus studies on humans and even those of animals are not available.
  • There are, however, in vitro (‘Test Tube Experiment’) studies.
  • These studies found YK11 did work similarly at ARs to dihydrotestosterone (DHT) but only partially activated the receptors which means androgenic side effects are not common.
  • On the WADA banned substance list.

Side Effects

  • As mentioned above studies are lacking.
  • We must base this section off anecdotal reports from bodybuilding forums.
  • Notable side effects included: Liver toxicity, natural testosterone suppression, decrease in HDL (good cholesterol) and joint pain.
  • Those taking YK11 might be at more risk of injuries since your muscle tends to grow a lot faster than the tendon whilst on this drug, perhaps due to the Follistatin.


  • It is taken orally once a day, some opt to splitting the dose into two during the day and taking once in the morning and once in the evening due to the unknown half-life (Some report 6 to 10 hours).
  • Doses for men range from 5mg to 10mg and 1 to 5mg for women.
  • It should not be used for more than 8 weeks.
  • It is reported to be the strongest SARM.

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