Mounjaro side effects: what to do and when to get help

When to get urgent help

Use the severity of your symptoms to decide the next step. Do not wait for a routine online appointment when you need urgent care.

For severe or persistent symptoms, ask the treating clinician what to do about your next dose. If you are unsure where to get help in New Zealand, call Healthline on 0800 611 116. For emergency symptoms, use 111.

Common Mounjaro side effects

Mounjaro slows stomach emptying and affects appetite. Stomach-related symptoms can be more noticeable when you start treatment or your dose increases. They include nausea, vomiting, diarrhoea, constipation, indigestion, heartburn, burping, bloating and wind. Some people also notice tiredness, dizziness or redness, itching or swelling where they inject.

Not everyone experiences these effects, and the pattern can change over time. A symptom being listed as common does not mean you should put up with it when it is severe, persistent or stopping you from eating and drinking. Tell your clinician about any symptom that worries you, including something not listed here.

The New Zealand Mounjaro consumer leaflet lists the medicine’s side effects and the action to take. Keep it with your prescription so you can check it when a new symptom appears.

Managing mild Mounjaro nausea and stomach upset

If symptoms are mild and you can drink normally, small adjustments may make meals more comfortable. Eat slowly, try smaller meals and stop when you feel comfortably full. Large, fatty or very spicy meals can make symptoms harder to manage. Sipping fluids regularly may be easier than drinking a large amount at once.

• Choose a smaller portion first, with more available if you are still hungry.
• Notice which foods or drinks aggravate symptoms and record the pattern.
• Avoid alcohol while you feel nauseated or dehydrated.
• Keep regular opportunities to eat, rather than going all day without food and having one large meal.
• Ask your clinician or pharmacist before adding an anti-nausea medicine or another treatment.

Contact your care team if vomiting or diarrhoea persists, or if you are struggling to get enough fluids or nutrition. If you have been told to restrict fluids for another condition, ask your clinician how to manage hydration. Our Mounjaro and alcohol guide covers the extra considerations around drinking.

Mounjaro constipation: practical first steps

For mild constipation without severe pain or vomiting, review fluids, fibre and movement. Drink regularly, include fibre-containing foods that you tolerate and keep gentle activity in your routine. Increase fibre gradually rather than making a sudden large change when you already feel bloated.

Record when you last passed a bowel motion, whether you are passing wind and any pain or nausea. A pharmacist or clinician can advise whether a constipation treatment is appropriate for you. Ask for help if the problem is not improving instead of repeatedly adding remedies yourself.

If a smaller appetite is making it difficult to build balanced meals, our dietitian support can help you discuss a workable eating plan.

Other medicines can change your risk

Low blood sugar is an important consideration when Mounjaro is used with certain diabetes treatments, particularly insulin or a sulfonylurea. Tell your prescriber about every medicine you use, including prescriptions from other clinicians. They may need to review your diabetes treatment and monitoring plan.

Signs of low blood sugar can include sweating, shaking, hunger, dizziness, confusion or difficulty concentrating. Follow the hypo treatment plan your diabetes clinician has given you. Severe confusion, seizures or unconsciousness are emergencies. Do not drive when you have symptoms of low blood sugar.

Alcohol can make low blood sugar harder to recognise or worse. Also tell the clinician about pregnancy plans and your contraception. The oral contraceptive pill needs additional consideration when starting Mounjaro and after dose increases.

How long do Mounjaro side effects last?

Some stomach symptoms improve as your body adjusts, but there is no single timetable that applies to everyone. The useful questions are whether symptoms are improving, how severe they are and whether you can manage normal fluids, food and daily activities.

Do not increase your dose while struggling with symptoms without speaking to your prescriber. A review can consider whether the dose, timing of an increase or wider treatment plan needs to change. Our Mounjaro dosage guide explains the standard stages and why increases are not automatic.

A new symptom is not always caused by the medicine. Your clinician may need to consider other causes, particularly if symptoms are unusual, worsening or happening after a period of stable treatment.

A useful symptom record for your review

You do not need a complicated diary. A few details help your clinician understand what happened:

• Pen strength and the date and time of the most recent injection.
• When symptoms began, how long they lasted and how they affected your day.
• What you could eat or drink and whether you were passing urine normally.
• Bowel changes, pain location and any fever or vision changes.
• Recent dose increases, missed injections and other medicine changes.
• What you tried and whether it helped.

For example: “I used my prescribed dose on Monday evening. Nausea began Tuesday morning. I can drink and eat small meals, but it is still affecting work on Thursday.” Add the actual strength and any warning signs. This is more useful than describing the problem only as “feeling bad”.

At Stela, a doctor follow-up costs $150, with monthly follow-up during the first three months of treatment. Use a routine appointment for an ongoing treatment review, and urgent services for the warning signs above.

Your questions