weight loss

3 minute read

What are the most common side effects of Mounjaro?

By Nick Harland | Medically reviewed by Dr Nimlan Shanmugathas

Mounjaro is a treatment for obesity that was approved for use in the UK in November 2023. That means eligible patients can now be prescribed Mounjaro privately or through the NHS.

As with any medication, there are a few side effects to be aware of. Let’s run through some of the most common ones, as well as some tips on what to do if you’re experiencing any of them.

Most common side effects of Mounjaro

During the clinical trials of Mounjaro, these were the most common side effects (reported by at least 5% of patients):

  • Nausea

  • Diarrhoea 

  • Indigestion

  • Vomiting

  • Constipation 

  • Stomach pain

Generally speaking, a higher proportion of patients reported side effects on the stronger doses of Mounjaro. This is normal, and by gradually increasing your dose, the risk of side effects is minimised.

Constipation and stomach pain were the only side effects that were less common on the stronger doses.

Less common side effects of Mounjaro

Other less common side effects of Mounjaro (reported by less than 5% of patients) include:

  • Quickened heart rate

  • Redness or swelling around the injection area

  • Skin rashes

  • Eczema

  • Acute gallbladder disease

  • Acute pancreatitis

Again, these side effects tended to be more common on the highest strength dose (15mg) of Mounjaro.

How long do the side effects last?

The side effects of Mounjaro shouldn’t last for more than a few weeks. They normally occur when you first start taking the medication, and when your dose increases. Your clinician will gradually increase your dose, so the risk of side effects is minimised.

Most patients report that the side effects of Mounjaro decrease over time as your body gets used to the medication.

What to do if you experience side effects from Mounjaro

Although most Mounjaro side effects are mild and subside quickly, they can still be unpleasant while they last. Here are a few things you can do if you’re struggling with any side effects.

  • Drink plenty of water: Some Mounjaro side effects (such as vomiting) can lead to further side effects (such as dehydration). That’s why it’s so important to stay hydrated whilst taking Mounjaro. Drinking plenty of water will also help you manage the effects of diarrhoea, constipation, and nausea.

  • Eat slowly: You’re likely to experience a reduced appetite on Mounjaro, which should help you to avoid overeating. However, try to focus on eating a little slower than normal when you eat. This can help to relieve nausea and stomach pain.

  • Use over-the-counter medication: There are plenty of over-the-counter medications that can help to relieve the most common Mounjaro side effects. Ask your local pharmacist to see what they would recommend.

  • Speak with your clinician. If any of these side effects continue to bother you, speak to a clinician. They might recommend a lower strength dose - or perhaps a different weight loss medication entirely. It may simply be that Mounjaro isn’t right for you.

The numan take

Clinical trials have proven Mounjaro to be an effective treatment that supports weight loss alongside a balanced diet and regular exercise. As with any medication, it’s important to be aware of any possible side effects and speak to your healthcare provider if you have an adverse reaction.