The most common GLP-1 side effects are nausea, diarrhea, constipation, vomiting and stomach discomfort. They are usually mild to moderate, show up in the first weeks or after a dose increase, and ease as your body adjusts. Severe stomach pain, dehydration or signs of an allergic reaction need prompt medical care.
- Stomach-related effects are the most common, and often fade within a few weeks.
- Starting low and stepping up slowly keeps them manageable.
- Smaller meals, eating slowly and staying hydrated help most people.
- Call your care team for severe or lasting pain, or if you cannot keep fluids down.
What are the most common side effects?
Nausea, diarrhea, constipation, vomiting, bloating, heartburn, tiredness and headache are the most reported. They come from the same effect that helps you eat less: food moves through your stomach more slowly.
| Side effect | When it shows up | What helps |
|---|---|---|
| Nausea | First weeks and after dose increases | Smaller meals, stop at the first sign of fullness, skip greasy food |
| Constipation | Can linger longer | Water, fiber, daily movement |
| Diarrhea | Usually the first weeks | Fluids, simple bland meals |
| Tiredness | Early weeks | Enough protein and calories, steady sleep |
How long do side effects last?
For most people, effects are strongest in the first few weeks and for a few days after each dose increase, then settle. If they do not ease, your clinician can keep you on your current dose longer or step you back down.
When should you call your care team?
Contact your care team or get urgent care for:
- Severe stomach pain that will not go away, with or without vomiting
- Vomiting or diarrhea that keeps you from holding down fluids
- Swelling of the face, lips or throat, or trouble breathing
- A lump or swelling in your neck, trouble swallowing or hoarseness
How does CMWL help you manage them?
Every plan includes unlimited physician support at no extra cost. Message your care team whenever something feels off, and they can adjust your pace so you stay on track.
Watch next: Common GLP-1 effects, and how to manage them →Frequently asked questions
Do side effects mean the medication is working?
Not necessarily. Many people lose weight with few side effects. Side effects reflect how your body adjusts, not how well the medication works.
Is tirzepatide or semaglutide easier on the stomach?
Side effects are similar for both. How you respond is individual, and your clinician can switch medications if needed.
Can I take anti-nausea medicine?
Ask your care team first. They can recommend options that are safe with your treatment.
Will side effects come back when my dose goes up?
They can, though they are often milder and shorter. Doses step up gradually to limit this.
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Sources
- Wegovy (semaglutide) injection. Prescribing information. Novo Nordisk.
- Zepbound (tirzepatide) injection. Prescribing information. Eli Lilly and Company.
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384:989-1002.
CMWL Chief Medical Officer and Yale-trained physician. Last reviewed October 14, 2026.
Read full bio →This article is for education only and does not replace personalized medical advice. Compounded medications are not FDA-approved. Talk to a licensed clinician about the risks and benefits of any treatment.
