Can Weight Loss Drugs Cause Gallstones? (October 2026)

01 · Your decision

Does this affect my choice of medicine?

It matters most if you are starting or considering a weight loss medicine and have had gallstones or gallbladder symptoms before. Your prescriber will take extra care, or may recommend against treatment, if you have a history of gallbladder problems, pancreatitis or severe digestive disease.¹³ Share your full medical history and medicine list during the consultation.

For Mounjaro, the leaflet lists gallstones and gallbladder inflammation among the common side effects.¹³ Inflammation of the gallbladder (cholecystitis) was uncommon in the weight-management trials, affecting between 1 in 1,000 and 1 in 100 people.¹ Our guide on whether Mounjaro can cause gallstones goes into more detail.

02 · Next step

What should I do next?

If you take another weight loss medicine, read its patient leaflet or ask your prescriber what applies to it. If you have a history of gallstones, read about weight loss medication with gallstones. If you want to discuss treatment, our weight loss clinic offers a free consultation reviewed by a GPhC-registered prescriber.

The same question comes up for the wider class, so see our guides on whether GLP-1 medicines can cause gallstones and weight loss injections and gallstones.

03 · Gallstones and weight loss

How gallstones relate to weight lost

Acute gallbladder problems on Mounjaro were linked to the amount of weight lost.¹ Trial averages do not predict your own result, and individual results vary.

There is no proven way to prevent pancreatitis or gallbladder problems while taking Mounjaro.¹³ What you can do is know the warning signs and tell your prescriber about your history first.

04 · Warning signs

Warning signs and serious side effects

Serious side effects are uncommon but need urgent attention. Severe, persistent stomach pain that may spread to your back, with or without vomiting, could be pancreatitis: stop using Mounjaro and get medical help straight away.¹³

Pain in the upper right abdomen, fever or yellowing of the skin or eyes could be a gallbladder problem, so get medical help straight away. Signs of a severe allergic reaction, such as swelling of the face or throat and difficulty breathing, also need immediate medical help.¹³

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

05 · Before you start

What to tell your prescriber before starting

Before you start, tell your prescriber if you have ever had pancreatitis, gallstones or gallbladder disease, or severe problems with your digestion.¹³ Also share every medicine you take.

Learn the warning signs, so you know when to get medical help straight away. Our prescribing team provides ongoing monthly reviews and side-effect support for Mounjaro customers.

06 · Other side effects

Other common side effects to know

Most Mounjaro side effects are digestive, such as nausea, diarrhoea, vomiting, constipation and abdominal discomfort. They are most likely when starting or increasing a dose, and for most people they ease within days to a few weeks as the body adjusts.¹³

Temporary hair shedding is also a recognised side effect, linked to rapid weight loss itself rather than a direct drug effect.¹³ See our guide on weight loss drugs and hair loss for more.