GLP-1 side effects: what's normal and when to call your doctor

Most side effects from GLP-1 medicines come from the same thing that makes them work: food moves through your stomach more slowly and your appetite drops. The result is usually mild and temporary. A few side effects are serious, though, and it's worth knowing them before your first dose.

Common side effects

• Nausea, the most common, especially in the first weeks and after dose increases
• Diarrhea or constipation
• Vomiting, indigestion, burping or heartburn
• Feeling full quickly, reduced appetite
• Tiredness
• Mild redness or itching at the injection site
• Hair shedding, usually linked to rapid weight loss

How to make them easier

• Eat smaller meals, slowly, and stop at the first sign of fullness.
• Go easy on fried, very fatty or very sugary foods, which often trigger nausea.
• Drink water through the day. Dehydration makes nausea and constipation worse and can strain your kidneys.
• Add fiber gradually and keep moving to help with constipation.
• Don't lie down right after eating if you have reflux.
• Tell your care team. Your clinician can slow the dose increase or hold a dose until you feel better.

When to get help right away

Stop the medication and seek urgent care for:

• Severe stomach pain that doesn't go away, with or without vomiting (possible pancreatitis)
• Pain in the upper right abdomen, fever, yellow skin or eyes (possible gallbladder problems)
• Signs of a serious allergic reaction: swelling of the face, lips or throat, trouble breathing
• Vomiting or diarrhea so severe you can't keep fluids down
• A lump in your neck, trouble swallowing or persistent hoarseness
• New or worsening depression or thoughts of self-harm (call or text 988)

If you take insulin or a sulfonylurea for diabetes, GLP-1 medicines can make low blood sugar more likely. If you use birth control pills, tirzepatide can reduce their effectiveness, so a backup method is recommended for four weeks after starting and after each dose increase.