Common side effects (SURMOUNT-1 pooled data)
- Nausea: ~24–31% (typically transient, peaks at dose escalation).
- Diarrhea: ~19–23%.
- Constipation: ~15–17%.
- Vomiting: ~8–12%.
- Abdominal pain: ~7–10%.
- Dyspepsia, eructation, fatigue, injection-site reactions, alopecia (less common).
Serious adverse events & boxed warning
Boxed warning (thyroid C-cell tumors): Tirzepatide caused thyroid C-cell tumors in rats; relevance to humans is unknown. Contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN-2).
Pancreatitis: Rare; discontinue if suspected.
Gallbladder events: Cholelithiasis and cholecystitis reported.
Hypoglycemia: Higher risk when combined with insulin or sulfonylureas in type 2 diabetes; dose-adjust accompanying therapy.
Acute kidney injury: Reported in association with severe GI side effects causing dehydration.
Hypersensitivity: Anaphylaxis and angioedema reported; discontinue if it occurs.
Diabetic retinopathy: Rapid A1C improvement may temporarily worsen retinopathy; monitor in patients with pre-existing retinopathy.
Contraindications
- Personal or family history of medullary thyroid carcinoma (MTC).
- Multiple endocrine neoplasia syndrome type 2 (MEN-2).
- Known hypersensitivity to tirzepatide or any product excipient.
- Pregnancy — discontinue at least 2 months before a planned pregnancy due to long half-life.
Drug interactions
Tirzepatide delays gastric emptying and may affect the absorption of orally-administered medications. The most clinically significant interaction is with oral contraceptives: Eli Lilly recommends a non-oral contraceptive method or addition of a barrier method for 4 weeks after initiation and for 4 weeks after each dose escalation. Adjust insulin and sulfonylureas in patients with type 2 diabetes to reduce hypoglycemia risk.
Managing GI symptoms during titration
- Eat smaller, more frequent meals; stop eating at the first sign of fullness.
- Avoid high-fat, fried, and very spicy foods during the first 1–2 weeks of each dose increase.
- Hydrate — 64+ oz water daily.
- For constipation: increase fiber gradually, add a stool softener if needed.
- For nausea: small portions of bland food (rice, toast, broth); ginger or peppermint can help.
- Communicate symptoms to your care team before any scheduled dose escalation.
When to call your clinician immediately
- Severe abdominal pain (especially upper-right or upper-middle, possibly radiating to the back) — rule out pancreatitis or gallbladder event.
- Persistent vomiting with inability to keep fluids down — dehydration risk.
- Signs of an allergic reaction: swelling of face/lips/tongue, difficulty breathing, hives.
- Sudden severe headache or visual changes.
- Signs of hypoglycemia (if on insulin or sulfonylureas): sweating, shakiness, confusion.