Mounjaro side effects and how to manage them
If you’re prescribed Mounjaro for weight loss or as a type 2 diabetes treatment, you may experience some side effects along the way. This is most common early in your treatment, or as you increase your dosage. Generally, Mounjaro side effects are mild and manageable.
If you’re looking for professional weight loss support, you may be eligible for NHS-funded help through Oviva, which can include access to weight loss medications, like Wegovy, along with a tailored weight loss plan and one-to-one coaching.
Key Takeaways
- Side effects of Mounjaro include nausea, diarrhoea, constipation and vomiting – they are most common early in your treatment or when you increase your dose.
- In rare cases, Mounjaro may cause more serious side effects – such as pancreatitis or allergic reactions. It’s important to speak to your GP if you’re concerned.
- For most people, side effects are mild and ease over time.
- You can help manage symptoms by resting, staying hydrated, eating well and speaking to your doctor about anti-nausea medication if needed.
What is Mounjaro?
Mounjaro (tirzepatide) is a once-weekly injection originally used to manage type 2 diabetes. It’s now also approved for weight management.
It works by mimicking two natural hormones (GIP and GLP-1) that help to:
- Regulate blood sugar
- Reduce appetite
- Increase fullness after eating
Mounjaro must be prescribed and monitored by a healthcare professional. Buying Mounjaro from unregulated sources online can carry serious health risks.
What are the common side effects of Mounjaro?
During clinical trials, a number of common side effects of Mounjaro were reported, including:
- Nausea
- Vomiting
- Constipation
- Diarrhoea
- Lack of appetite
- Low energy or fatigue
- Indigestion
- Bloating
Side effects are most common when you first start taking Mounjaro or when your dose is increased. For most people, these effects are mild and settle over time.
Many of the digestive symptoms, like nausea or bloating, are linked to slower digestion. Mounjaro affects how quickly food moves through your stomach, which can help reduce hunger but may also cause discomfort at first.
Other effects, like tiredness or appetite loss, are connected to how the medication supports weight loss – by making you feel fuller for longer and helping you eat less overall.
What are the rare side effects?
While uncommon, you could potentially experience other side effects of Mounjaro, like:
- Gallbladder issues (e.g., gallstones)
- Rashes around the injection site
- Swelling and other signs of an allergic reaction
- Pancreatitis (inflammation of the pancreas)
These are rare, but are more serious – you should speak to your GP or seek urgent medical advice if you experience any of these.
In animal studies, tirzepatide (the active ingredient in Mounjaro) was linked to a higher risk of thyroid tumours in rats. However, this effect has not been confirmed in humans. Even so, Mounjaro should not be used if you or a close family member have a history of medullary thyroid carcinoma (a rare type of thyroid cancer) or MEN 2 (multiple endocrine neoplasia syndrome type 2).
If you’re unsure about your medical history, speak to your GP before starting any new medication.
If you experience severe stomach pain, stop taking the medication and see your doctor.
How long do Mounjaro side effects last?
Everyone reacts differently, but for most people, side effects last a few days to a couple of weeks and gradually ease as the body adjusts.
They’re most likely to occur:
- When you first start treatment
- After each dose increase
This is why medical supervision is essential – your healthcare team can help adjust your dose if needed.
Nutrition support also plays a role. Knowing what to eat and when can help reduce symptoms like nausea or bloating.
While Oviva doesn’t currently prescribe Mounjaro, our NHS-funded service offers access to other approved weight loss medications, along with expert support from doctors, dietitians and health coaches to help manage side effects and build sustainable habits.
Over time, you learn what’s healthy and good for you, and you feel empowered. Oviva fits perfectly into my life.
What can you do to manage Mounjaro side effects?
Managing side effects from Mounjaro often comes down to simple strategies – including how and what you eat, how much rest you get, and when to reach out for support.
Eat smaller, balanced meals
One of the best ways to ease common side effects is to focus on small, regular meals that are rich in protein and fibre. This can help reduce digestive discomfort and support your overall health.
If you’re feeling nauseous or sick
If you feel nauseous:
- Avoid large portions and high-fat foods, which may make nausea worse
- Stick to dry, bland foods (like toast or plain rice) if your stomach feels unsettled
- Speak to your GP or prescribing clinician if symptoms persist or become severe
- Alcohol may also make these symptoms worse – so it’s best to avoid or limit alcohol while on Mounjaro.
Coping with diarrhoea
If you experience diarrhoea:
- Stay hydrated by sipping water regularly
- Consider using an oral rehydration powder to replace lost electrolytes
- Avoid fizzy drinks and fruit juices, which can irritate your digestive system further
Managing fatigue
Tiredness is another possible side effect, especially as your body adjusts. To help manage this:
- Listen to your body – building in quiet time during the day can help you recover
- Make sure you’re eating a balanced, nourishing diet
- Eat slow-release energy foods like oats, wholegrains, and pulses
- Avoid skipping meals, even if your appetite is lower – it can lead to energy dips
- Try gentle movement, like a short walk, to boost energy levels
When should you speak to a doctor?
If you experience side effects, it’s a good idea to speak to your doctor or healthcare professional straight away. They may be able to adjust your dose or offer support to help you feel more comfortable.
You’re not expected to push through alone, and it’s important to act if you’re worried about the impact Mounjaro side effects are having on your lifestyle or mental health.
It’s important to speak to your doctor immediately if you:
- Have persistent or severe nausea, diarrhoea or vomiting
- Experience sharp or intense abdominal pain
- Notice signs of an allergic reaction, like swelling, rashes, or breathing difficulties
You don’t have to go on your weight loss journey alone
Oviva’s NHS-funded weight management programme gives you everything you need in one place.
- Expert-led support from dietitians, doctors and a personal health coach
- A structured plan focused on sustainable weight loss – no crash diets
- Access to prescription medication like Wegovy, if clinically appropriate
- An easy app to track your progress, stay motivated and get personalised advice
- Fully remote – get it all from the comfort of your home
There’s a reason why 97% of our users recommend us.
Download your info pack to speak to your GP about getting started.
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