SARMMyostatin Inhibitor

YK-11

SARM / myostatin inhibitor

Also known as YK11, yk

Half-life

~6-10 hours

What is YK-11?

Steroidal SARM that also inhibits myostatin. One of the most aggressive SARMs available.

How YK-11 works

Steroidal SARM-like compound with AR agonism and proposed myostatin suppression via follistatin signaling.

Benefits & uses

Strong muscle-building (myostatin inhibition)
Reputation for dramatic gains

Common uses: Extreme muscle mass, myostatin inhibition, strength.

YK-11 dosage

Protokol doesn't recommend doses for prescription or controlled compounds. Any figures below are reference or observational reports — dosing should be set with a qualified clinician.

Protocol notes: 5-15mg daily. Myostatin inhibitor + partial androgen agonist. Most suppressive SARM. Run with mini PCT.
Commonly reported: Observational only; experimental, minimal human dataObservational use reports — not a recommendation.

YK-11 half-life

~6-10 hours (estimated)

YK-11 side effects

Joint pain, liver toxicity, significant suppression. Very high risk profile.

Liver stress risk
Hormonal suppression
Very limited human safety data
Strong testosterone suppression
Possible liver stress (steroidal structure)
Lipid shift
Hair loss/aggression reported

Warnings & monitoring

🔴 Very little human data — experimental. Requires bloodwork + medical monitoring
Strongly suppressive — PCT needed
FDA-warned / WADA-banned / gray-market
Not approved for human use

YK-11 interactions

with RAD-140
Caution · high
YK-11 is a myostatin inhibitor with SARM properties and significant anabolic effect. Stacking with RAD-140 creates very high suppression. Exogenous testosterone as a base is strongly recommended.
Timing: Advanced-only stack; expect full suppression requiring testosterone base or PCT
with RAD-140
Caution · moderate
YK-11 is a myostatin inhibitor with steroidal structure — highly potent and suppressive. Combined with RAD-140, androgenic load is significant. This stack is closer to a mild steroid cycle in terms of HPTA impact.
Timing: Use low doses of each; 8-week maximum; PCT required

Commonly stacked with

Ligandrol (LGD-4033)Testolone (RAD-140)

Track YK-11 in Protokol.

Log doses, model half-lives, check interactions, and line it all up against your bloodwork. Free on iPhone and Android.