Mounjaro side effects: what you should know

Common Mounjaro Side Effects

The most commonly reported side effects with Mounjaro are related to the digestive system. These are more likely to happen when starting treatment or after a dose increase.

Common side effects may include:

These effects are usually mild to moderate. For many people, they lessen over time as the body adjusts to the medicine.

Some people may also experience:

If side effects are persistent, bothersome, or worsening, it is important to speak with your healthcare provider. They may recommend adjustments or provide advice to help manage symptoms safely.

• Nausea
• Diarrhoea
• Vomiting
• Constipation
• Stomach (abdominal) pain
• Indigestion
• Decreased appetite
• Injection site reactions (such as redness or discomfort where the injection is given)
• Feeling tired (fatigue)
• Heartburn

Serious Side Effects of Mounjaro

Serious side effects with Mounjaro are uncommon, but they can happen. It is important to recognise symptoms early and seek medical attention promptly if needed.

One of the most serious risks is inflammation of the pancreas (acute pancreatitis). This can cause sudden, severe pain in the stomach that may spread through to the back and does not go away. It may occur together with vomiting or diarrhoea. This type of pain is usually intense and different from usual digestive discomfort. If you develop these symptoms, seek urgent medical care.

Mounjaro may also cause gallbladder problems, including gallstones or inflammation of the gallbladder. Symptoms can include sudden, severe pain in the upper abdomen, fever, yellowing of the skin or eyes (jaundice), or pale or claycoloured stools. These symptoms require medical attention.

Another important but less common risk is slowing down or blockage of the intestines. Signs may include severe abdominal pain, ongoing bloating, difficulty passing wind, persistent constipation, nausea or vomiting, or feeling the urge to open your bowels without being able to pass anything. If you experience these symptoms, contact your healthcare provider promptly.

Low blood sugar (hypoglycaemia) can happen, particularly if Mounjaro is used together with insulin or certain diabetes tablets that increase insulin levels, such as gliclazide. Symptoms of mild to moderate low blood sugar can include sweating, hunger, tremor or shakiness, lightheadedness, dizziness, drowsiness, mood changes such as irritability or anxiety, sleep disturbance, blurred vision, tingling in the hands, feet or lips, slurred speech, or a fast or irregular heartbeat. More severe hypoglycaemia may cause disorientation, seizures, or unconsciousness. If you experience symptoms of low blood sugar that are severe, persistent, or difficult to manage, seek medical care urgently.

Serious allergic reactions are rare but possible. Symptoms may include rash, hives, itching, rapid swelling of the face, lips, mouth, throat or neck, or difficulty breathing or swallowing. These reactions require immediate emergency treatment.

Some people with existing diabetic eye disease (diabetic retinopathy) may notice changes in their vision. If you experience new or worsening vision problems while using Mounjaro, contact your healthcare provider. Monitoring may be required.

Mounjaro has also been associated with thoughts of suicide or death in rare cases. If you experience changes in mood, unusual thoughts, or thoughts of harming yourself, talk to your healthcare provider. It is important not to ignore changes in mental wellbeing.

If you notice any symptoms that feel severe, unusual, or rapidly worsening, it is safest to seek medical advice straight away. Early assessment can reduce the risk of complications.

Medicines That May Interact with Mounjaro

Before starting Mounjaro, it’s important to tell your healthcare provider about all the medicines you take. This includes prescription medicines, pharmacy medicines, and any vitamins or supplements.

Because Mounjaro lowers blood sugar, using it alongside other diabetes medicines can increase the risk of low blood sugar (hypoglycaemia). This is particularly relevant if you use insulin or certain diabetes tablets that increase insulin levels, such as gliclazide. To reduce this risk, your healthcare provider may adjust the dose of your other diabetes medicines when you begin Mounjaro or when your dose changes.

Mounjaro also slows the movement of food through the stomach. This can affect how quickly some oral medicines are absorbed into your body. In most cases this does not cause problems, but it can be important for medicines that require precise dosing. If you take medicines where timing or dose accuracy is critical, your healthcare provider will consider this when prescribing Mounjaro.

If you experience ongoing vomiting or diarrhoea, this can also affect how well your body absorbs other medicines and may increase the risk of dehydration. If this happens, contact your healthcare provider for advice.

Never adjust your medicines or stop treatment without medical guidance. If you are unsure whether a medicine you take could interact with Mounjaro, it is best to ask.

Mounjaro and Alcohol

If you drink alcohol, it is important to discuss this with your healthcare provider while using Mounjaro.

Alcohol may mask the symptoms of low blood sugar (hypoglycaemia) or make them worse. This is particularly important for people who are also using insulin or certain diabetes medicines that increase insulin levels, such as gliclazide. Because the warning signs of low blood sugar can become harder to recognise, there is a greater risk that it may not be treated promptly.

Mounjaro can also cause nausea, vomiting, or stomach discomfort, particularly when starting treatment or increasing the dose. Alcohol may worsen these symptoms in some people.

A Final Word

Mounjaro can play an important role in managing type 2 diabetes and, for some people, supporting weight management. As with all prescription medicines, it has risks as well as benefits.

Many side effects are mild and improve over time, particularly during the early stages of treatment. However, some side effects can be serious and require prompt medical attention. Being aware of possible symptoms can help you respond quickly if something doesn’t feel right.

If you have concerns about side effects at any stage of treatment, speak with your healthcare provider. They can assess your symptoms and advise whether any changes to your treatment are needed.

Important safety information

Prescription medicine. Mounjaro® (tirzepatide) is used in adults with type 2 diabetes to improve blood sugar control. In adults who are overweight or have obesity, Mounjaro® is also used for weight management, including weight loss and weight maintenance. Mounjaro® contains the active ingredient tirzepatide and is available in pre-filled KwikPen® devices in the following dose strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg (each pen contains four weekly doses). Mounjaro® has risks and benefits. Ask your healthcare provider if Mounjaro® is right for you. Use strictly as directed. If you experience side effects, see your healthcare provider. Common side effects include nausea, diarrhoea, vomiting and constipation. Serious side effects can include inflammation of the pancreas (pancreatitis), gallbladder problems, allergic reactions and low blood sugar (particularly when used with insulin or certain other diabetes medicines). For more information, please refer to the Mounjaro® approved professional information (package insert) available at: https://www.sahpra.org.za/registered-health-products/