Does GLP-1 Affect the Gallbladder? (October 2026)

01 · The core answer

Does GLP-1 affect the gallbladder?

Yes, it can. Gallstones are the main concern, and they are listed as a side effect of tirzepatide in the UK product information.

Inflammation of the gallbladder is rarer. Inflammation of the gallbladder (cholecystitis) was uncommon in the weight-management trials, affecting between 1 in 1,000 and 1 in 100 people.¹ Most people taking these medicines never develop a gallbladder problem, but it is a recognised risk and worth knowing about before you start.

The product information also states that acute gallbladder problems were linked to the amount of weight lost.¹

02 · Your decision

Is this relevant to me, and what should I do next?

It is most relevant if you have had gallstones, gallbladder pain or gallbladder surgery in the past. Your prescriber will take extra care, or may recommend against treatment, if you have a history of gallbladder problems.¹ Always share your full medical history and medicine list during the consultation.

If you have no gallbladder history, the practical steps are simple: know the warning symptoms and report anything unusual. Our wider guide to gallbladder health on GLP-1 treatment goes deeper on day-to-day management.

If you are considering treatment, you can read about the Mounjaro pen and start a free consultation, where a GPhC-registered prescriber reviews your history, including any gallbladder concerns. Our weight loss clinic page explains the wider service.

03 · Why gallstones can form

Why gallstones can form on GLP-1 treatment

The product information states that acute gallbladder problems were linked to the amount of weight lost.¹

04 · Weight loss speed and risk

Weight loss, trial results and gallbladder risk

Because the product information ties gallbladder problems to the amount of weight lost, it helps to understand how much weight these medicines can produce. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.²

These are trial averages, and individual results vary. These figures show how large the change in body weight can be, and the product information links acute gallbladder problems to the amount of weight lost.

Dose increases happen in stages, with at least 4 weeks on each dose, depending on how you respond. If you have abdominal pain, tell your clinical team rather than waiting; for severe pain, get medical help straight away.

Weight loss also brings benefits that matter to overall health. In trials, weight loss on tirzepatide came with average improvements in waist size, blood pressure, cholesterol and blood-sugar measures.² A gallbladder risk sits alongside those benefits and should be weighed with your prescriber, not in isolation. For the wider picture of how these medicines change the body, see how GLP-1 affects metabolism.

05 · Warning signs to act on

Gallbladder warning signs: when to seek help

Serious side effects are uncommon but need urgent attention. The product information says to seek immediate medical help for pain in the upper right abdomen, fever or yellowing of the skin or eyes, which may point to gallbladder problems.¹¹³

Get medical help straight away if these symptoms appear; do not wait for your next scheduled review.

Gallbladder pain can be confused with other things. Severe, persistent stomach pain that may spread to your back, with or without vomiting, can signal possible pancreatitis, which also needs medical help straight away.¹ Seek immediate medical help for signs of a severe allergic reaction, such as swelling of the face or throat and difficulty breathing. You do not need to work out the cause yourself. Describe the pain, where it sits and what else you notice, and let a clinician assess it.

You can also report any suspected side effect through the MHRA Yellow Card scheme.¹⁹

06 · Protecting your gallbladder

Can you prevent gallbladder problems?

There is no proven way to prevent pancreatitis or gallbladder problems while taking Mounjaro. Before you start, tell your prescriber if you have ever had pancreatitis, gallstones or gallbladder disease, or severe problems with your digestion. Severe, persistent stomach pain that may spread to the back, with or without being sick, could be pancreatitis — stop using Mounjaro and get medical help straight away. Pain in the upper right of the abdomen, fever or yellowing of the skin or eyes could be a gallbladder problem — get medical help straight away.

If you have had gallstones before, say so at the consultation. Your prescriber can weigh your history and decide whether treatment is suitable, whether extra monitoring makes sense, or whether another approach is safer.

07 · Other organs and side effects

Which other organs can GLP-1 medicines affect?

The gallbladder is only part of the picture. Tirzepatide acts on appetite and stomach emptying, so the digestive system is where most side effects appear.

Pancreas. Your prescriber will take extra care if you have a history of pancreatitis.¹

Kidneys and liver. Mounjaro is not known to damage kidneys or liver directly, and no dose adjustment is needed for mild to moderate kidney or liver impairment. The practical risk is indirect, through dehydration from severe vomiting or diarrhoea.¹

Thyroid. In rodent studies tirzepatide caused thyroid C-cell tumours; it is not known whether this applies to humans, and no increase has been shown in human trials. Tell your prescriber if you or a close relative have had medullary thyroid cancer or the inherited condition MEN 2.¹

Brain and mood. Regulators have reviewed whether GLP-1 medicines are linked to low mood or suicidal thoughts and the EMA's safety committee concluded the evidence does not support a causal link. Our page on how GLP-1 affects the brain covers this.¹⁷

If you have thoughts of harming yourself or ending your life, get help straight away. Call 999 or go to A&E if you are in immediate danger. In England you can call NHS 111 and choose the mental health option, any time. You can also call Samaritans free on 116 123, day or night. Tell your prescriber about any change in your mood while taking Mounjaro.

Pregnancy. Mounjaro should not be used during pregnancy or while trying to conceive. See whether GLP-1 can affect pregnancy for more. Mounjaro should be stopped at least one month before trying to conceive. If you become pregnant during treatment, stop the medicine and tell your prescriber promptly.

For effects on vision, see our page on whether GLP-1 medicines affect eyesight; diabetic retinopathy is one of the histories your prescriber will take extra care over.

08 · Stopping and clearance

Pausing or stopping treatment

If gallbladder symptoms develop, your prescriber decides what happens next, which may include pausing or stopping treatment. Stopping should always be planned with your prescriber, with diet and activity habits ready to carry the load.

Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹

Never stop or change treatment on your own because of mild digestive symptoms. Speak to your clinical team first; for severe, persistent stomach pain, pain in the upper right abdomen, fever or yellowing of the skin or eyes, get medical help straight away.