Ibutamoren (MK-677)

What is Ibutamoren (MK-677)?

MK-677, also called ibutamoren, is an oral, once-daily growth-hormone secretagogue that lands at 4.5-5.0/10, Neutral, because its real strengths and real harms almost perfectly cancel out. It works by activating the ghrelin receptor, which nudges your own pituitary to release more growth hormone and raises IGF-1 into the young-adult range, per Patchett 1995. What makes it stand out from the injectable peptides people compare it to is the evidence behind it. It has been through multiple double-blind, placebo-controlled human trials, including a 2-year study and a 563-patient pivotal trial. That is far more human data than most things in this category have.

From the BioHarmony report, reviewed 2026-09-08.

How it is thought to work

Agonist at the growth-hormone-secretagogue receptor (GHS-R1a), the same receptor ghrelin uses

Safety watch-outs

• Rising fasting glucose or HbA1c: stop and consult a clinician, especially with diabetes or pre-diabetes.
• New edema or any breathlessness, ankle swelling, or unusual fatigue: stop, given the documented congestive-heart-failure signal.
• Any active or suspected cancer: do not use, because growth-hormone and IGF-1 signaling can promote proliferation.
• Carpal-tunnel-type numbness or tingling that worsens: reduce the dose or stop.

Full risk profile in the BioHarmony report.

Dosing as published

No approved-label or study protocol is recorded for Ibutamoren (MK-677) yet.

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