Independent UK medicine guidance
Mounjaro constipation relief: what works
Constipation is listed as a very common side effect when Mounjaro is used for weight management, affecting more than 1 in 10 people. It is common rather than very common in adults treated for type 2 diabetes, except in the type 2 diabetes cardiovascular disease study where it was very common. It often appears because you are eating and drinking less, and because tirzepatide slows the movement of food through your gut. For most people it is manageable, but it should not be ignored.
Key facts
- Constipation is a very common side effect of Mounjaro in weight management: more than 1 in 10 people (UK leaflet, revised August 2026).
- In adults treated for type 2 diabetes it is common, up to 1 in 10. In the type 2 diabetes cardiovascular disease study it was very common.
- Slower stomach emptying, eating less and drinking less all contribute, so fluid, fibre and movement are the first things to fix.
- No bowel movement for several days with severe pain, swelling or vomiting is not routine constipation and needs same-day advice.
Why does Mounjaro cause constipation?
- Slower stomach emptying and gut transit
- Eating noticeably less food, which means less bulk to move
- Drinking less fluid without realising, because thirst cues can fade with appetite
- Less dietary fibre when portions shrink
- Reduced physical activity on low-energy days
What may help
Fluids first
Drink regularly through the day, taking small, frequent amounts if larger drinks feel uncomfortable. Dehydration makes stools harder and is one of the most common drivers.
Fibre, gradually
Add fibre-containing foods such as vegetables, fruit, oats, beans and wholegrains step by step rather than suddenly. A sharp fibre increase without enough fluid can make bloating worse.
Keep moving
Regular movement, even short walks, helps stimulate the bowel. You do not need intense exercise for this effect.
Ask a pharmacist
If lifestyle steps are not enough, a pharmacist can recommend a laxative suitable for you and your other medicines. Do not stack several laxatives on your own, and do not use them long term without advice.
When to get medical advice
Contact your prescriber, GP or NHS 111 if:
- Constipation lasts more than a week despite self-care
- You have severe abdominal pain or vomiting
- Your abdomen becomes swollen and you cannot pass stool or wind
- There is blood in your stool
- You have unintentional symptoms such as new weakness or dizziness alongside it
Severe pain, vomiting, marked swelling or being unable to pass stool or wind needs prompt assessment rather than more self-treatment, as these can be signs of a blocked bowel. Severe persistent abdominal pain spreading to the back can also indicate pancreatitis.
Evidence update, September 2026: SURPASS-CVOT constipation figure in the revised SmPC
On 8 September 2026 the electronic medicines compendium (eMC) published a revised Mounjaro Summary of Product Characteristics with a text revision date of 29 August 2026. It adds safety results from SURPASS-CVOT, a large trial that compared tirzepatide with dulaglutide, another injectable diabetes medicine, in adults with type 2 diabetes and established cardiovascular disease. The study-specific figures relevant to this page are:
- Constipation: 12.8% of participants taking tirzepatide
- For context, the same study reported nausea in 25.1%, diarrhoea in 24.9% and abdominal distension in 4.6%
The figure substantiates the very common category recorded for that study population in the UK patient leaflet revised in August 2026. It does not add a new side effect and it does not change the warning signs above.
Source: Mounjaro Summary of Product Characteristics (eMC), text revised 29 August 2026, section 4.8
Common questions
How common is constipation on Mounjaro?
Constipation is listed as very common in weight management, meaning it may affect more than 1 in 10 people. It is often most noticeable when starting treatment or after a dose increase. The frequency differs by why the medicine is prescribed: in adults treated for type 2 diabetes constipation is listed as common, while in the type 2 diabetes cardiovascular disease study reported in the August 2026 leaflet it was very common. If you take Mounjaro for weight loss, the weight-management figure is the one that applies.
Can I take a laxative with Mounjaro?
Many people can, but the right choice depends on your health and other medicines, so ask a pharmacist to recommend one suitable for you. Do not combine several laxatives on your own or use them long term without advice.
When is constipation serious?
Seek prompt medical help for severe abdominal pain, vomiting, a swollen abdomen, being unable to pass stool or wind, or blood in your stool. These are not ordinary treatment side effects and need assessment.
Related guides
Primary sources: Mounjaro Patient Information Leaflet (eMC) • NHS constipation guidance
Explore other side effects
Tap a point on the body to jump to that symptom, or choose from the full list below. The pink marker shows where you are now.
© 2026 Medstack Ltd. Written and published by Monj (monj.co.uk). You are welcome to link to this page or quote a short extract with a credit and a link. Republishing the text, page structure, safety-routing design or price data, in whole or in part, including to train or ground an automated system, is not permitted without written permission. See our independence statement and editorial and review policy.
Sources referenced on this page
Linked from the text above:
- Mounjaro Summary of Product Characteristics (eMC), text revised 29 August 2026, section 4.8 www.medicines.org.uk
- Mounjaro Patient Information Leaflet (eMC) www.medicines.org.uk
- NHS constipation guidance www.nhs.uk
Standing primary references for every Monj page:
- Mounjaro (tirzepatide) Summary of Product Characteristics and Patient Information Leaflet, electronic medicines compendium
- MHRA Drug Safety Update: GLP-1 receptor agonists
- NICE TA1026: tirzepatide for managing overweight and obesity
- General Pharmaceutical Council register of pharmacies
- MHRA Yellow Card scheme
