Mounjaro side effects and how to treat them 

Around 1 in 10 people get the most common Mounjaro side effects, like nausea, vomiting, or constipation. These usually happen when you first start treatment or increase your dose, as your body gets used to the medication. The good news? They’re typically mild and can often be managed easily at home.

In this guide, our clinicians explain the side effects of Mounjaro, how to recognise them, and what you can do to lower your chances of getting them. We’ll also share simple ways to relieve symptoms at home and let you know when it’s time to speak to your doctor.

Three Key Takeaways

• The most common side effects of Mounjaro are nausea, diarrhoea, constipation, and vomiting. These are usually mild and often go away on their own.
• Most side effects can be managed safely at home with small diet or lifestyle changes, or with over-the-counter remedies.
• If your side effects are hard to cope with, or you’re worried about them, speak to your prescriber.

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What are the most common Mounjaro side effects?

The very common Mounjaro side effects (affecting more than 1 in 10 people) are:

• nausea
• diarrhoea
• constipation
• vomiting
• stomach pain

While very common, not everyone will get these and how long they last will vary from person to person.

Managing very common Mounjaro side effects

You can reduce and manage most common Mounjaro side effects by making small lifestyle and dietary changes. Plus, over the counter treatments like antacids can help too.

Nausea (feeling sick)

To deal with nausea we recommend:

• eating smaller meals more frequently
• stopping eating the moment you start to feel full
• sticking to bland foods like rice, bread, or crackers
• drinking hot herbal teas, like ginger or peppermint
• taking small, regular sips of cold water
• avoiding fatty and processed foods
• taking your mind off it – watch some TV, listen to some music
• getting some fresh air – take a walk, if you can, or sit outside

Nausea is usually only temporary and should ease soon. To prevent it, make sure you’re well hydrated, and sticking to small, regular meals.

If nausea lasts for more than a couple of days, speak to your doctor.

Diarrhoea

If you’re getting diarrhoea we recommend:

• Staying hydrated. Diarrhoea can lead to dehydration, which can make you sick and make other side effects worse.
• Taking rehydration sachets. These over-the-counter sachets make sure you stay hydrated and keep your electrolytes topped up.
• Eat foods that are easy to digest. Think bananas, plain toast, or rice.
• Avoid natural laxatives, like caffeine and alcohol. These not only dehydrate you but can make diarrhoea worse.

If you have diarrhoea and it doesn’t go away after 7 days or if you notice any blood in your stool, you need to get medical advice from a doctor.

Constipation

If you’re dealing with constipation, focus on eating a balanced diet rich in fibre from fruits, vegetables, and whole grains, and increase your fibre intake gradually to avoid diarrhoea. 

Drink plenty of water to help keep stools soft and support digestion, and try to get regular exercise, even a daily walk can help. Establish good toilet habits by going at a regular time, not rushing or holding it in, and using a comfortable posture, such as resting your feet on a small stool.

If needed, speak to your prescriber about using an over-the-counter laxative.

Learn more about constipation and Mounjaro

Rashes and injection site reactions

It’s not unusual to see rashes, bruising, or swelling at your chosen injection site. You might also notice some pain and itching. This usually settles as you get used to taking the injections, but it’s worth keeping an eye on if it gets worse or doesn’t go away. If you’re dealing with issues at your injection site, try:

• Regularly rotating where you do your injection. Avoiding the same spot gives your skin time to heal.
• Using antihistamine cream. Injection site rashes might be caused by a mild allergy, and an antihistamine can help reduce it.
• Making sure your injection site is always clean. Clean any area you’re going to inject thoroughly before starting.
• Numbing the area before injecting. This can prevent irritation and pain.

Common Mounjaro side effects

The common Mounjaro side effects (affecting 1 in 10 people) are:

• itching, eczema, or a rash
• acid reflux (heart burn)
• dizziness
• indigestion
• bloating
• burping
• wind
• injection site reactions (redness or itching)
• low blood pressure
• hair loss
• low blood sugar
• feeling tired (fatigue)
• increased levels of lipase (a pancreatic enzyme) in the blood
• increased levels of calcitonin (a thyroid hormone that regulates your calcium levels) in the blood

These side effects also tend to go away on their own or when you stop treatment.

Some common side effects can be made worse, or more likely to occur, by other medicines you’re taking. That’s why it’s important to tell your clinician about any medications you’re on before starting Mounjaro.

For example, certain treatments for type 2 diabetes, like metformin, can increase your risk of low blood sugar when combined with Mounjaro.

If you begin any new medication while taking Mounjaro, let your prescriber know so they can check it’s still safe and suitable for you.

“Worrying about side effects is totally natural, especially when you’re starting a new medication. Try to remember that most side effects are mild and serious side effects are very rare. By knowing what the side effects can be, you put yourself in the best position to deal with them at home or to know when to speak to a healthcare professional for advice. In most cases, side effects go away on their own as your body gets used to the medication, so you shouldn’t have to worry too much.”