Ibutamoren (MK-677) Side Effects
Medically reviewed by Dr. Jonathan Snipes, MD
Reviewed for clinical accuracy · Last reviewed July 22, 2026 · Review policy
Quick answer
The most common Ibutamoren (MK-677) side effects are increased appetite and water retention / edema, and are usually mild and dose-related. Serious effects are less common; the full breakdown and cautions are below.
| Effect | Frequency |
|---|---|
| Increased appetite | Common |
| Water retention / edema | Common |
| Lethargy or fatigue | Less common |
| Raised blood glucose / insulin resistanceA significant concern with longer-term use | Less common |
| Joint pain | Reported |
Ibutamoren's side effects follow from sustained growth-hormone elevation plus its ghrelin-like activity. Increased appetite and water retention are common and often noticeable. The more serious concern is metabolic: it can raise fasting blood glucose and reduce insulin sensitivity, which matters for anyone with or at risk of diabetes, and is one reason its long-term safety is not established. It is also prohibited in sport.
Frequently asked questions
What are the most common Ibutamoren (MK-677) side effects?+
The most common Ibutamoren (MK-677) side effects are increased appetite and water retention / edema. See the full frequency table above for less common and rare effects.
Is Ibutamoren (MK-677) safe?+
Ibutamoren (MK-677)'s human safety is not well characterized because it has not completed formal human safety trials. Any use should be through a licensed clinician and a legitimate pharmacy, not research-chemical suppliers.