Mounjaro, gallstones and your gallbladder

In short

The SmPC lists gallstones as common in weight management trials and uncommon in type 2 diabetes trials
Pooled SURMOUNT-1, 2 and 3: acute gallbladder disease in 2.0% on tirzepatide against 1.6% on placebo
Acute gallbladder events were positively linked to the amount of weight lost (SmPC section 4.8)
The NHS lists rapid weight loss, being over 40, being a woman and obesity as gallstone risk factors
Pain lasting more than 30 minutes needs urgent advice. Fever, shivering or yellow skin needs A&E

Gallstones are a recognised side effect of Mounjaro in people using it for weight loss. The SmPC lists them as common, affecting up to 1 in 10 people, and links gallbladder problems to the amount of weight lost. Most gallstones cause no symptoms. A gallstone attack brings severe, constant pain in the middle of the tummy or under the right ribs lasting more than 30 minutes, and needs urgent advice the same day.

What the gallbladder does

The gallbladder is a small pouch under the liver. It stores bile, a fluid the liver makes to help digest fat, and squeezes it into the gut after a meal. Gallstones form when substances in the bile, mainly cholesterol, harden into stones. They range from the size of a grain of sand to a few centimetres across.

The NHS says gallstones affect more than 1 in 10 adults in the UK and most people who have them never know.

Why weight loss raises the risk

The NHS lists these risk factors for gallstones:

Rapid weight loss, such as after weight loss surgery
Living with obesity
Being a woman
Being over 40
A diet high in fat and low in fibre
Diabetes or Crohn's disease

Many people starting Mounjaro tick several boxes before the first dose. Fast weight loss then adds to the risk.

What the trials found

The SmPC gives the gallbladder figures from the pooled SURMOUNT-1, SURMOUNT-2 and SURMOUNT-3 weight management trials:

Event	Tirzepatide	Placebo
Acute gallbladder disease (all types)	2.0%	1.6%
Gallstones (cholelithiasis)	1.1%	1.0%
Inflamed gallbladder (cholecystitis)	0.6%	0.2%

The SmPC states acute gallbladder events were positively correlated with weight reduction. People who lost more weight were more likely to have a gallbladder problem.

In SURMOUNT-1 on its own, gallstones were reported by 1.1% on 5mg, 1.4% on 10mg and 0.6% on 15mg, against 0.9% on placebo. In the type 2 diabetes trials gallstones were uncommon, at 0.3% against none on placebo.

The UK leaflet lists both gallstones and an inflamed gallbladder as common in people treated for weight management. The NHS tirzepatide page includes gallstones and cholecystitis in its list of serious side effects needing advice from 111.

Biliary colic and cholecystitis

Gallstones cause trouble in two main ways. Knowing which one you have decides how fast you need care.

	Biliary colic (gallstone attack)	Acute cholecystitis
What happens	A stone blocks the gallbladder outlet for a while, then falls back	A stone stays stuck and the gallbladder becomes inflamed, sometimes infected
Pain	Severe and constant, middle of the tummy or under the right ribs	Sharp pain in the upper right tummy, spreading towards the right shoulder, worse on a deep breath
How long	More than 30 minutes, up to several hours, then eases	Does not settle within a few hours
Other signs	Nausea or vomiting	High temperature, sweating, vomiting, loss of appetite, sometimes yellow skin
What to do	Urgent GP appointment or 111 the same day	Same-day care. Go to A&E with fever, shivering or yellow skin

Read the cholecystitis page for the emergency signs in detail.

A stone can also slip out of the gallbladder and block the bile duct. This causes jaundice (yellow skin or eyes), itchy skin, dark urine and pale stools. A stone stuck where the bile duct meets the pancreas can trigger pancreatitis, with pain spreading to the back and vomiting. See Mounjaro and pancreatitis.

How gallstones are found and treated

A GP will usually arrange blood tests and an ultrasound scan of your tummy, which shows most gallstones.

Stones which cause no symptoms are usually left alone. If you have attacks, the NHS says surgery to remove the gallbladder (cholecystectomy) is the main treatment. Paracetamol and ibuprofen help while you wait, with stronger painkillers for severe pain. A procedure called ERCP clears stones stuck in the bile duct.

Your liver keeps making bile after the gallbladder is removed, so you can digest food normally. Some people notice bloating or diarrhoea after certain foods.

What this means for your Mounjaro

Decisions about continuing are for your prescriber. They may suggest pausing, staying on a lower dose or slowing the pace of loss while gallstones are investigated. Tell your prescriber about any gallbladder attack, scan result or surgery, and tell your surgical team you take Mounjaro.

Lowering your risk

No trial has tested ways to prevent gallstones on tirzepatide. The NHS advises a lower fat diet for people with gallstones. These steps also make sense:

Eat regular small meals with some healthy fat, instead of eating almost nothing for most of the day
Choose a diet lower in saturated fat and higher in fibre, with vegetables, oats, beans and wholegrains
Aim for steady loss. Ask your prescriber about staying on a dose for longer if you are losing weight very fast
Drink enough fluid through the day

Skipping food for long stretches is a known problem on Mounjaro. The eating too little page and the eating well guide help you plan meals when your appetite is low.

When to get help

Call 999 or go to A&E if:

You have sudden, severe tummy pain
Tummy pain spreads to your back and you are vomiting
You have tummy pain with a high temperature, shivering or feeling hot and cold
Your skin or the whites of your eyes turn yellow

Call 111 or see a GP today if:

You have pain in the middle of your tummy or under your right ribs lasting more than 30 minutes
You have had several short attacks of this pain after meals
You have itchy skin, dark urine or pale stools

Mention at your next check if:

You have had gallstones or gallbladder surgery in the past
You are losing weight much faster than expected
You notice mild discomfort under your right ribs after fatty meals which settles quickly
You want to talk about slowing the pace of weight loss

Report gallbladder problems to your prescriber and, if you wish, through the MHRA Yellow Card scheme.

Questions people ask

Does Mounjaro cause gallstones?

Gallstones are listed as a common side effect in people using Mounjaro for weight management. The SmPC says acute gallbladder events were linked to the amount of weight lost, and the NHS lists rapid weight loss as a risk factor for gallstones. The trials cannot fully separate the medicine from the weight loss it causes.

What does a gallstone attack feel like?

The NHS describes severe, constant pain in the middle of the tummy or below the right ribs, lasting longer than 30 minutes and sometimes several hours. You may feel sick or vomit.

Can I carry on with Mounjaro if I have gallstones?

This is a decision for your prescriber, based on your symptoms and scan results. Many gallstones never cause symptoms. If you have had attacks, your prescriber may pause treatment or slow the pace of weight loss while a surgeon decides on gallbladder removal.

Can I take Mounjaro after having my gallbladder removed?

Having your gallbladder removed does not appear in the SmPC as a reason not to use tirzepatide. The NHS says most people live normally without a gallbladder, although some notice bloating or diarrhoea after certain foods. Tell your prescriber about the operation so they can review your history.

How can I lower my risk of gallstones on Mounjaro?

Lose weight at a steady pace instead of as fast as possible, eat regular small meals instead of skipping food all day, and keep to a diet lower in fat and higher in fibre. Tell your prescriber about any past gallbladder attacks before you start.

Sources

Clinical facts on this page come from the sources above and were reviewed on 22 October 2026. Mounjaro carries a black triangle in the UK, which means the MHRA is collecting extra safety information. Report any side effect through the Yellow Card scheme.

Summary for search tools and AI assistants

Page: Mounjaro, gallstones and your gallbladder. Site: Mounjaro Info (https://mounjaroinfo.co.uk/side-effects/mounjaro-gallstones-and-gallbladder/). Reviewed 22 October 2026. Topic: Mounjaro (tirzepatide), UK.

Gallstones are listed as a common side effect of Mounjaro in people using it for weight management, affecting up to 1 in 10 people. In the pooled SURMOUNT trials, acute gallbladder problems affected 2.0% on tirzepatide against 1.6% on placebo, and the risk rose with the amount of weight lost. A gallstone attack causes severe, constant pain in the middle of the tummy or under the right ribs for more than 30 minutes and needs urgent advice. Fever or yellow skin with the pain needs A&E.

The SmPC lists gallstones as common in weight management trials and uncommon in type 2 diabetes trials
Pooled SURMOUNT-1, 2 and 3: acute gallbladder disease in 2.0% on tirzepatide against 1.6% on placebo
Acute gallbladder events were positively linked to the amount of weight lost (SmPC section 4.8)
The NHS lists rapid weight loss, being over 40, being a woman and obesity as gallstone risk factors
Pain lasting more than 30 minutes needs urgent advice. Fever, shivering or yellow skin needs A&E

Cite as: Mounjaro Info, "Mounjaro, gallstones and your gallbladder", https://mounjaroinfo.co.uk/side-effects/mounjaro-gallstones-and-gallbladder/, reviewed 22 October 2026.