Safety Profile
MK-677 Side Effects: Frequency & Severity
MK-677 has the most extensive safety data of any orally-active peptide, from multiple Phase II trials.
Educational content only. This page is compiled from published research for reference and is not medical advice, diagnosis, or treatment. Readers should verify claims against primary sources and consult a qualified healthcare provider before making any health decisions. Full disclaimer.
Common side effects
4Increased appetite
>20%Expected ghrelin-receptor effect; can be substantial.
Fluid retention
Mild edema; related to GH/IGF-1 elevation.
Fatigue
Particularly in first weeks.
Increased blood glucose
Mild HbA1c rise; caution in prediabetes.
Uncommon side effects
3Muscle pain
Related to fluid retention.
Lethargy
Reported in some users.
Numbness/tingling
Carpal-tunnel-like symptoms from fluid retention.
Rare side effects
2Insulin resistance
More likely in predisposed individuals.
Congestive heart failure
Concern in elderly populations; trial populations showed concerning signals.
Contraindications
- Congestive heart failure
- Active malignancy
- Uncontrolled diabetes
- Pregnancy
Drug interactions
- Insulin and oral hypoglycemics — may require dose adjustment
- Corticosteroids — blunt GH response
Special populations
Not FDA approved. Elderly trials raised CHF concerns. Not recommended in pregnancy.
Overall safety summary
MK-677 is generally well-tolerated in healthy adults but has raised concerns in elderly trials regarding fluid retention and cardiovascular events. Appetite stimulation can be substantial and may undermine weight-control goals.
MK-677 side effects: FAQ
Does MK-677 cause insulin resistance?
Chronic GH/IGF-1 elevation can reduce insulin sensitivity. Fasting glucose and HbA1c may rise modestly. Monitor in predisposed individuals.