Safety information · Internal patient-safety page
Tirzepatide safety summary
Tirzepatide is a dual GIP / GLP-1 receptor agonist that reduces appetite and slows gastric emptying. The dual mechanism delivers stronger weight reduction than single-pathway GLP-1 medicines in head-to-head trials. It is prescribed for chronic weight management alongside a reduced-calorie diet and increased physical activity.
What it's used for
- Once-weekly self-injection in the thigh, abdomen or upper arm.
- Dose is escalated step-wise (2.5 mg → 5 → 7.5 → 10 → 12.5 → 15 mg) every 4 weeks while the body adapts.
- Combined with diet and physical activity, tirzepatide complements, not replaces, lifestyle change.
Most common side effects
- Nausea, vomiting and diarrhoea.
- Constipation, dyspepsia, abdominal pain.
- Decreased appetite, fatigue.
- Injection-site reactions.
- Hypoglycaemia when combined with insulin or sulfonylureas.
Serious side effects: stop and seek care
- Severe abdominal pain radiating to the back (possible pancreatitis): stop and seek urgent care.
- Gallbladder problems: sudden right-upper abdominal pain, jaundice, fever.
- Severe dehydration from prolonged vomiting / diarrhoea, risk of acute kidney injury.
- Sudden vision changes in patients with diabetic retinopathy.
- Severe allergic reaction.
Who should not take it
- Personal or family history of medullary thyroid carcinoma or MEN 2.
- Pregnancy, planned pregnancy in the next 2 months, or breastfeeding.
- History of pancreatitis.
- Type 1 diabetes or diabetic ketoacidosis.
- Severe gastroparesis.
Interactions to flag
- Insulin or sulfonylureas: risk of hypoglycaemia; the doctor may adjust those.
- Oral contraceptives: tirzepatide can reduce their absorption around the first dose and after each up-titration; a barrier method or a switch to a non-oral method is advised for 4 weeks.
- Oral medicines with a narrow absorption window: timing may need adjusting.
- Warfarin: closer INR monitoring during the first weeks.
- Alcohol: heavy use raises pancreatitis risk.
Message us in the app chat if you notice any of these
- Severe or persistent vomiting, dehydration, or inability to eat for more than 48h.
- New, severe abdominal pain that doesn't ease: A&E first.
- Pregnancy or a positive pregnancy test: stop the medicine immediately.
- A new medication or condition since your last consultation.
EMA: Mounjaro product information
Back to your consultationThis page summarises information from the regulator-approved leaflet for reference only. It is not medical advice and does not replace the assessment of an EU-licensed doctor. Your doctor will review your individual history, dose and interactions during your consultation.