Can you take Mounjaro with IBS?

Jump to: How Mounjaro affects the gut | IBS subtypes: what to expect | Managing IBS symptoms on Mounjaro | Foods to focus on | When to speak to your GP | Frequently asked questions | Take home message

You can take Mounjaro (tirzepatide) if you have irritable bowel syndrome (IBS), though the medication may affect your symptoms in unpredictable ways.

IBS affects approximately 10-20% of the UK population, making it one of the most common gastrointestinal conditions.¹

Many people with IBS also struggle with their weight, often due to the complex relationship between gut health, stress, and eating patterns.

No studies have directly investigated how Mounjaro affects people with IBS. The potential benefits and risks are based on our understanding of how the medication influences gut motility and digestion.

Some people with IBS report improvements in their symptoms while taking Mounjaro, while others find their symptoms temporarily worsen. The outcome often depends on your IBS subtype and how you manage the transition.

How Mounjaro affects your gut

Mounjaro is a dual-action weight-loss injection that mimics two hormones: GLP-1 and GIP. These hormones communicate with your brain’s appetite control centre to lower hunger and food-seeking behaviour.²

The medication also significantly slows gastric emptying, meaning food stays in your stomach longer. This creates a sustained feeling of fullness but can also affect how your digestive system functions overall.

Research shows that GLP-1 decreases gastrointestinal motility and inhibits the migrating motor complex in both healthy people and those with IBS.³ Put simply, Mounjaro slows down the movement of food through your digestive tract.

This slowing effect is why Mounjaro commonly causes gastrointestinal side effects. A systematic review found that people taking tirzepatide experienced:⁴

• Nausea in approximately 24% of users
• Diarrhoea in 16.2% of users
• Constipation in 2.5% of users
• Dyspepsia (indigestion) in 7.1% of users

For someone without IBS, these side effects are usually temporary and ease within the first few weeks. For someone with IBS, they may interact with existing symptoms in complex ways.

IBS subtypes: what to expect on Mounjaro

Your IBS subtype significantly influences how you might respond to Mounjaro. Research on GLP-1 medications and IBS suggests different effects depending on whether you have IBS-D, IBS-C, or IBS-M.⁵

Comparison: Mounjaro effects by IBS subtype

Interestingly, a 2025 systematic review found that GLP-1 receptor agonists significantly reduced pain intensity in IBS patients.⁶ The medication appears to reduce visceral hypersensitivity, which is a common cause of IBS-related discomfort.

This doesn’t mean Mounjaro is a treatment for IBS, but it suggests that some people with IBS may experience unexpected improvements in their symptoms alongside weight loss.

Managing IBS symptoms while on Mounjaro

Most gastrointestinal side effects occur during dose escalation and typically improve within 4-8 weeks as your body adjusts.⁷ 

By being proactive and developing some healthy habits while on the medication, you’re less likely to experience uncomfortable side effects.

For nausea and discomfort

Nausea is the most common side effect of Mounjaro and can be particularly challenging if you already have IBS-related digestive sensitivity.

• Eat 3 balanced meals a day with healthy snacks between
• Avoid lying down immediately after eating
• Choose easily digestible foods during the first few weeks, like white fish, scrambled eggs, mashed potato, and cooked vegetables
• Ginger tea or ginger supplements may help settle your stomach

For constipation

If you have IBS-C or develop constipation on Mounjaro, these tips can help:

• Increase water intake to at least 2 litres a day
• Add fibre gradually, as sudden increases can worsen symptoms
• Include magnesium-rich foods like leafy greens and nuts
• Gentle movement, like a short walk after meals, stimulates digestion
• Consider a stool softener if needed (discuss with your pharmacist)

For diarrhoea

If you have IBS-D or experience medication-related diarrhoea:

• Eat a diet based on whole foods
• Stay well hydrated with water and electrolyte drinks
• Limit ultra-processed foods and takeaways
• Reduce caffeine and alcohol intake
• Consider temporarily reducing fibre if symptoms are severe
• Monitor for signs of dehydration, especially in the early weeks

Foods to focus on with IBS and Mounjaro

Eating a diet based on whole foods becomes even more important when managing both IBS and Mounjaro.

Protein-first approach

Protein is essential for maintaining muscle mass during weight loss. Aim for a palm-sized portion at each meal.

Good options that are typically well-tolerated with IBS include:

• Chicken and turkey (plain, not heavily spiced)
• Fish, particularly oily fish like salmon
• Eggs (often well-tolerated even with IBS)
• Tofu and tempeh (some people with IBS tolerate these better than beans)
• Greek yoghurt (if you tolerate dairy)

Low-FODMAP vegetables

If you follow a low-FODMAP approach for IBS, focus on vegetables that are less likely to trigger symptoms:

• Carrots, courgettes, and aubergines
• Spinach and other leafy greens
• Bell peppers and tomatoes
• Green beans and cucumber

Complex carbohydrates

Choose carbohydrates that provide sustained energy without triggering IBS symptoms:

• White or basmati rice (often better tolerated than wholegrain for IBS)
• Oats (if tolerated)
• Potatoes and sweet potatoes
• Sourdough bread (the fermentation process reduces FODMAPs)

Foods to limit or avoid

Some foods may worsen both IBS symptoms and Mounjaro side effects:

• Spicy foods (may worsen nausea and digestive discomfort)
• Alcohol (irritates the gut and can worsen dehydration)
• Caffeine in excess (stimulates gut motility unpredictably)
• Artificial sweeteners (particularly sorbitol and mannitol)

When to speak to your GP

While some digestive changes are expected when starting Mounjaro, certain symptoms warrant medical attention.

Contact your GP or prescriber if you experience:

• Severe or persistent diarrhoea lasting more than a week
• Signs of dehydration: dizziness, dark urine, extreme thirst
• Blood in your stool or black, tarry stools
• Severe abdominal pain that doesn’t improve
• Significant worsening of your IBS symptoms that affects daily life
• Inability to keep fluids down for more than 24 hours

Your prescriber may recommend adjusting your dose, extending the time between dose increases, or trying different management strategies.

It’s also worth keeping your IBS management strategies in place. Continue any prescribed IBS medications unless advised otherwise, and maintain contact with your gastroenterologist if you have one.

Frequently asked questions

Can Mounjaro make IBS worse?

Mounjaro may temporarily worsen IBS symptoms, particularly during the first few weeks of treatment or when increasing your dose.

The most common issues are nausea, constipation, or diarrhoea. However, these effects typically improve as your body adjusts to the medication.

Should I take Mounjaro if I have IBS-C or IBS-D?

Both IBS-C and IBS-D patients can take Mounjaro, but with different considerations. If you have IBS-C, monitor for worsening constipation and prioritise hydration and fibre.

If you have IBS-D, the medication-induced diarrhoea may temporarily worsen symptoms, but the slowing effect on gut transit could eventually help.

Will Mounjaro help my IBS symptoms?

There’s no guarantee, but some people report improvements in IBS symptoms while taking Mounjaro. Research suggests GLP-1 medications may reduce abdominal pain and visceral hypersensitivity. Weight loss itself can also improve IBS symptoms by reducing inflammation.

What foods should I avoid on Mounjaro if I have IBS?

Avoid high-fat and fried foods, spicy dishes, alcohol, excessive caffeine, and artificial sweeteners. These can worsen both Mounjaro side effects and IBS symptoms. Focus on bland, easily digestible foods during the first few weeks.

How long do Mounjaro side effects last with IBS?

Most gastrointestinal side effects improve within 4-8 weeks as your body adjusts. If symptoms persist beyond this time or significantly worsen your IBS, speak to your prescriber about adjusting your treatment plan.

Can I continue my IBS medication while taking Mounjaro?

In most cases, yes. Continue any prescribed IBS medications unless your doctor advises otherwise. Mounjaro is unlikely to interact with common IBS treatments, but always inform your prescriber of all medications you take.

Should I follow a low-FODMAP diet while on Mounjaro?

If you already follow a low-FODMAP diet for IBS, there’s no reason to stop while taking Mounjaro. The reduced appetite may actually make it easier to avoid trigger foods. However, ensure you’re still getting adequate nutrition from the foods you do eat.

Will losing weight improve my IBS?

Research suggests that weight loss can improve IBS symptoms, possibly by reducing inflammation. One study found that moderate weight loss reduced IBS symptoms by 27% in women with obesity.⁸ However, the relationship between weight and IBS is complex, and weight loss alone may not resolve all symptoms.

Can Mounjaro cause bloating?

Yes, bloating is a possible side effect of Mounjaro due to the slowing of gastric emptying. This can be particularly noticeable if you already experience bloating as part of your IBS. Eating smaller meals and avoiding carbonated drinks may help.

Is it safe to exercise on Mounjaro with IBS?

Yes, gentle exercise is encouraged and can actually help manage both IBS symptoms and Mounjaro side effects. Walking, swimming, and yoga are good options. Avoid intense exercise immediately after eating, and stay well hydrated.

Take home message

You can take Mounjaro if you have IBS, but expect some adjustment period as your body adapts to the medication’s effects on your digestive system.

The key is proactive management: eat smaller meals, prioritise hydration, keep a symptom diary, and communicate regularly with your healthcare team.

Many people with IBS find that once they get through the initial weeks, the medication becomes manageable alongside their existing IBS symptoms. Some even report improvements in abdominal pain and discomfort.

Focus on eating a diet based on whole foods rich in protein and vegetables, and don’t hesitate to seek medical advice if your symptoms significantly worsen.

References

1. 1. NICE. (2021). Irritable bowel syndrome in adults: diagnosis and management (CG61)
   2. Jastreboff, A.M., et al. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine, 387(3), 205-216.
   3. Hellström, P.M., et al. (2008). GLP-1 suppresses gastrointestinal motility and inhibits the migrating motor complex in healthy subjects and patients with irritable bowel syndrome. Neurogastroenterology & Motility, 20(6), 649-59.
   4. Khan, A., et al. (2023). Tirzepatide-Induced Gastrointestinal Manifestations: A Systematic Review and Meta-Analysis. Cureus, 15(10), e47137.
   5. Tack, J., et al. (2013). Role of glucagon-like peptide-1 in the pathogenesis of irritable bowel syndrome. International Journal of Molecular Medicine, 31(4), 1021-1027.
   6. Mostafa, E.S. & Alrasheed, M.M. (2025). Improvement of irritable bowel syndrome with glucagon like peptide-1 receptor agonists: a systematic review and meta-analysis. Frontiers in Endocrinology, 16, 1548346.
   7. Richards, R., et al. (2025). A Remotely Delivered, Semaglutide-Supported Weight Management Program: 12-Month Outcomes From a Retrospective Service Evaluation. JMIR Formative Research, 9(1), e72577.
   8. Halmos, E.P., et al. (2014). A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology, 146(1), 67-75.e5.