GLP-1 side effects: what's common and when to get help
Updated October 17, 2026
GLP-1 medications such as semaglutide and tirzepatide work on hormones that regulate appetite and digestion. Most side effects come from that same effect on your gut.
Common side effects
- Nausea
- Diarrhea or constipation
- Vomiting
- Stomach pain, bloating or indigestion
- Tiredness
- Headache
- Redness or irritation where you inject
These are most likely in the first weeks and right after a dose increase, and they often ease over time.
Simple ways to manage them
- Eat smaller meals and stop when you feel full.
- Go easy on greasy, fried or very sweet foods.
- Drink water through the day. Vomiting and diarrhea can dehydrate you.
- Add fiber gradually if you’re constipated.
- Tell your care team. Your provider can slow down your dose increases.
When to get help right away
Contact your provider or get medical care if you have:
- Severe stomach pain that doesn’t go away, with or without vomiting
- Pain in the upper right belly, fever, or yellowing skin or eyes
- Signs of dehydration, like dizziness or very little urine
- A lump or swelling in your neck, trouble swallowing, or hoarseness
- Swelling of the face or throat, or trouble breathing
If you think you are having a medical emergency, call 911.
Before surgery
Tell any doctor who plans to sedate you or give you anesthesia that you take a GLP-1 medication. These medicines slow digestion, which matters for procedures.
This guide is general information, not medical advice. Talk to your provider about your own treatment.