What are the side effects of MK-677 (Ibutamoren)?
The most commonly reported MK-677 (Ibutamoren) side effects are aggressive appetite stimulation, water retention / bloat, numb/tingling hands (carpal-tunnel-like). Most are mild and tend to be dose dependent. It is generally avoided with active malignancy. Human clinical evidence for MK-677 (Ibutamoren) is limited, so this reflects reported and observed effects, not a complete safety profile.
Reported MK-677 (Ibutamoren) side effects
- Aggressive appetite stimulation
- Water retention / bloat
- Numb/tingling hands (carpal-tunnel-like)
- Insulin resistance creeping up over long use
- Lethargy at higher doses
Who should avoid it
- Active malignancy
- Pre-diabetic or insulin-resistant baseline
- Pregnancy / nursing
Bloodwork worth tracking
- IGF-1 baseline + week 8
- Fasting glucose / insulin every 8 weeks
References
- Effects of an oral ghrelin mimetic on body composition and clinical outcomes — Nass R et al., Ann Intern Med, 2008
- Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure — Svensson J et al., Journal of Clinical Endocrinology & Metabolism, 1998
- LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report — Cardaci TD et al., Experimental Physiology, 2022
Pepdex is an editorial reference, not medical advice. Peptides vary in legal and approval status by country, many are research compounds without full human safety data. Talk to a qualified clinician before starting anything.
More on MK-677 (Ibutamoren)
Last updated 2026-06-06.