Most GLP-1 side effects are gastrointestinal and dose-related. They typically peak in the first 4–8 weeks after a dose increase and improve as your body adapts.
Common (≥10% of patients)
- Nausea
- Constipation
- Diarrhea
- Vomiting
- Decreased appetite (the therapeutic effect, not a side effect)
Less common
- Heartburn / GERD
- Fatigue
- Headache
- Burping (notably sulfur burps with semaglutide — see our Wegovy sulfur burps guide)
When to call your prescriber
- Severe persistent abdominal pain (rule out pancreatitis)
- Yellow skin or eyes (rule out gallbladder disease)
- Vision changes
- Persistent vomiting preventing hydration
Always discuss side-effect concerns with your prescriber. This page is editorial, not medical advice.
Related resources
More in Side effects
How do I manage GLP-1 nausea?
Eat smaller meals, prioritize protein, avoid greasy or very sweet foods, and stay hydrated. Nausea typically improves after the first 4–8 weeks.
Are GLP-1 medications safe?
GLP-1 drugs have been studied and used for over 15 years. Common side effects are GI. Rare risks include pancreatitis, gallbladder issues, and a boxed warning for thyroid C-cell tumors based on rat studies.