Dr Ashwin Sharma

Article by Dr Ashwin Sharma

Mounjaro Side Effects: What They Are and How To Manage Them

Every medication can cause side effects, and Mounjaro weight loss injections are no different. If you’re just starting your weight management treatment, it’s important to know which symptoms you may experience, and how you can manage them. 

Here, our experts break down common and serious side effects, and offer tips to relieve discomfort and your treatment as easy as possible.

Common Mounjaro side effects 

When you first start any weight loss injectable, it’s normal to notice a few minor side effects. Remember, this is simply your body adjusting to Mounjaro, and they should settle with time. 

The majority of side effects are related to the digestive system. You may notice nausea — especially on higher doses of Mounjaro — and diarrhoea, which can lead to dehydration if you’re not drinking enough fluids throughout the day. Some people may experience vomiting when they first take Mounjaro, but this tends to settle over time. 

You may also have a decreased appetite, due to the drug helping to slow your digestion. This can also lead to indigestion and constipation, which can often be managed by maintaining a healthy fibre-rich diet, staying hydrated, and doing regular exercise.

You could also experience fatigue, or reactions at the injection site. It’s important that you monitor any side effects and consult your clinical team if they continue or become worse.

Who shouldn’t use Mounjaro? 

Mounjaro isn’t suitable for you if you’re currently pregnant or breastfeeding. 

You shouldn’t take Mounjaro if you’re allergic to tirzepatide, or any other ingredients in the medication. Severe allergic reactions are rare, but you should seek medical attention if you notice a skin rash, swelling or difficulty breathing. 

If you have pre-existing conditions like kidney issues, a history of pancreatitis or severe digestive problems, speak to your doctor before starting Mounjaro.

Serious side effects + warnings

Other rare side effects of Mounjaro may include pancreatitis, hypoglycemia, or gallbladder disease. 

For more information about side effects, you can view the Mounjaro patient information leaflet. 

When to seek medical attention

Seek medical advice if you notice any symptoms of thyroid cancer, such as difficulty swallowing, shortness of breath, hoarseness, or an unusual neck lump.

If you develop abdominal pain, dizziness, severe stomach problems or severe dehydration, you also should seek medical advice immediately and inform them that you’re using Mounjaro.

You should also get urgent medical advice if you experience symptoms of an allergic reaction, such as difficulty breathing, a skin rash, or swelling of the lips, face or tongue. 

Managing side effects

Consistency is key when taking Mounjaro, so it’s important that you’re comfortable with your dosage. Here are some tips you can follow to keep side effects at bay:


To reduce nausea and vomiting, eat small portions, limit fatty and spicy foods, and sip calming drinks like ginger tea [1]. For constipation, include high-fibre foods and plenty of fluids in your diet [1]. Stay hydrated and rest to manage diarrhoea [2].


Over-the-counter antacids may help with heartburn [2]. If side effects are severe or persistent, contact our clinician team for support.

Dosage and storage

If you miss a dose, take it as soon as you remember within four days. If it’s been more than four days, skip it and take the next dose on the regular day [3]. Store Mounjaro in the fridge and use within 21 days if kept at room temperature [3].

Remember, most side effects tend to resolve within a few days as your body adjusts to the medication [4]. If they’re severe or persistent, contact your clinical team for support. 

Got a question about side effects? Speak to our dedicated clinical team for any extra support. 


[1] – https://www.drugwatch.com/drugs/mounjaro/side-effects/

[2] – https://www.healthline.com/health/drugs/mounjaro-side-effects

[3] – https://www.webmd.com/drugs/2/drug-184168/mounjaro-subcutaneous/details

[4] – https://my-bmi.co.uk/medical-therapy/mounjaro-side-effects/

Dr Ashwin Sharma
Dr Ashwin Sharma
Dr Ashwin Sharma is a medical doctor and writer with a particular interest in health technology, artificial intelligence and medical weight loss. He completed his training at the University of Leicester and Imperial College London, and has since been exploring the intersections of medicine, technology, and communication.
Originally published March 19 2024, updated April 16 2024