Overview
This article explains the potential side effects of Mounjaro® (tirzepatide), including common, uncommon, and rare reactions, as well as serious symptoms that require urgent medical attention. Use this guide to understand what side effects to expect, when they are most likely to occur, and when to seek medical advice while using Mounjaro® for weight loss.
Use this article when you want to:
Understand what Mounjaro® side effects to expect, and how common they are.
Recognise which symptoms need urgent medical attention.
Know what to do if you experience a side effect while using Mounjaro®.
MedExpress is here to support you throughout your weight loss journey with Mounjaro® (tirzepatide), including helping you understand possible side effects and how to manage them.
What Should I Know About Mounjaro® Side Effects in General?
While Mounjaro® has helped many people reach their health goals, side effects can occur. Most side effects are:
Mild to moderate.
More likely when starting Mounjaro® or increasing the dose.
Likely to improve over time as your body adjusts.
What Are the Very Common Side Effects of Mounjaro® (More Than 1 in 10 People)?
Nausea
Vomiting
Diarrhoea
Stomach (abdominal) pain
Constipation
Low blood sugar (hypoglycaemia), particularly when Mounjaro® is combined with a sulphonylurea or insulin for type 2 diabetes
What Are the Common Side Effects of Mounjaro® (Up to 1 in 10 People)?
Dizziness
Low blood pressure
Indigestion
Heartburn
Bloating
Burping
Flatulence
Fatigue
Injection site reactions (redness, swelling, or pain at the injection site)
Allergic skin reactions (such as rash, itching, or eczema)
Hair loss (often associated with weight loss rather than Mounjaro® itself)
What Are the Uncommon Side Effects of Mounjaro® (Up to 1 in 100 People)?
Injection site pain
Changed sense of taste
Increased heart rate
If any Mounjaro® side effects persist, worsen, or cause concern, seek medical advice.
What Are the Serious Side Effects of Mounjaro® That Need Urgent Medical Attention?
What Are the Signs of Acute Pancreatitis?
Acute pancreatitis is inflammation of the pancreas. Symptoms may include:
Severe and persistent stomach pain that may spread to the back.
Severe vomiting (for example, vomiting three or more times in one day).
Vomit that looks like coffee grounds or contains blood.
Call 999 or attend A&E immediately if you experience symptoms of acute pancreatitis while using Mounjaro®.
What Are the Signs of Acute Gallbladder Disease (Cholecystitis)?
Acute gallbladder disease can cause:
Sudden, sharp pain in the upper right side of the abdomen.
Pain that worsens when breathing deeply.
A very tender abdomen.
Call 999 or attend A&E immediately if you experience symptoms of gallbladder disease while using Mounjaro®.
What Are the Rare Side Effects of Mounjaro® (Up to 1 in 1,000 People)?
What Are the Signs of a Severe Allergic Reaction (Anaphylaxis)?
Symptoms of a severe allergic reaction may include:
Difficulty breathing
Swelling of the lips, tongue, or throat
Difficulty swallowing
Rapid heartbeat
Call 999 or attend A&E immediately if you experience symptoms of a severe allergic reaction.
How Should I Manage Mounjaro® Side Effects Overall?
Mounjaro® side effects are most common when starting treatment or increasing your dose.
Many Mounjaro® side effects improve with time.
If you experience any side effect, whether listed here or not, you can report it through the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk.
If you are ever unsure or worried about symptoms while taking Mounjaro®, seek medical advice promptly.