We’re here to support you throughout your weight loss journey, offering tips to help you manage side effects and providing reassurance if you have any concerns.
While Mounjaro has helped many people reach their health goals, it’s crucial to understand what to watch for along the way. Below, we’ve outlined the most common and rare side effects, along with guidance on when to seek help.
Very common: These side effects may occur in more than 1 in 10 people and usually go away over time. They are most common when first starting Mounjaro and when increasing the dose.
- Examples: feeling sick (nausea), vomiting, diarrhoea, stomach pain, constipation.
Common: These side effects may occur in up to 1 in 10 people.
- Examples: dizziness, a reduction in blood pressure, indigestion, heartburn, bloating, burping, flatulence, fatigue, injection site reactions (redness, swelling), gallstones, allergic reaction (e.g., rash, itching, and eczema), low blood pressure, hair loss
Uncommon: These side effects may occur in up to 1 in 100 people.
- Examples: Injection site pain, changed sense of taste, increased heart rate. While these symptoms are generally not serious, if you are concerned or symptoms persist, please visit our dedicated side effects landing page for more guidance on what to do.
- SERIOUS: acute pancreatitis. This is inflammation of the pancreas that can cause severe stomach pain which can radiate to your back that doesn’t go away. Most patients feel very ill with pancreatitis and may present with severe vomiting (i.e., vomiting 3 times or more in one day, or having coffee ground or blood in the vomit). You should call 999 or attend A&E right away if you experience these symptoms.
- SERIOUS: acute gallbladder disease. This is inflammation of the gallbladder (also known as cholecystitis) that can cause a sudden sharp pain in the upper right side of your stomach that radiates towards your right shoulder. The affected area of the stomach will feel very tender and deep breathing can make the pain worse.
You should call 999 or attend A&E right away if you experience these symptoms.
Rare: These side effects may occur in up to 1 in 1000 people.
- SERIOUS: severe allergic reaction (anaphylaxis). This can present as difficulty breathing, swelling of lips, tongue and/or throat, difficulty swallowing, rapid heartbeat. You should call 999 or attend A&E right away if you experience these symptoms.
Managing Side Effects
If you experience any side effects—whether listed here or not—please visit our GLP-1 hub for more guidance on what to do.