Did Mounjaro Cause My Gallstones? The Science Explained (UK)

Q: Are gallstones common on Mounjaro?

Gallstones are not common for most users, but gallbladder-related events are a recognised potential risk, particularly during rapid weight loss.

Short answer: Mounjaro (a GLP-1 medication) does not directly “create” gallstones — but the rapid weight loss that can happen on GLP-1 treatment can increase gallstone risk in some people.

If you’ve developed gallstones while losing weight on Mounjaro, you’re not alone. I ended up needing emergency NHS gallbladder surgery after losing 6 stone on GLP-1 — and this post explains what the evidence and physiology suggest, without panic or overclaiming.

Read my full emergency surgery story here →

Does Mounjaro cause gallstones?

Mounjaro does not directly form gallstones. However, significant and rapid weight loss — which often occurs with GLP-1 medications — is a recognised risk factor for gallstone formation.

Gallstones commonly form when:

The liver releases more cholesterol into bile during fat loss
The gallbladder empties less often or less completely
Cholesterol crystals build up and solidify into stones

This is why gallstones also occur with:

Very low calorie diets
Bariatric surgery
Rapid fat loss programmes
GLP-1 assisted weight loss

Why rapid weight loss increases gallstone risk

When body fat breaks down quickly, bile composition can change.

Cholesterol concentration in bile can increase
Gallbladder motility can reduce (it may “sit” fuller for longer)
Bile can crystallise more easily, forming stones over time

In plain English: the faster the weight comes off, the more your bile environment can shift toward stone formation in susceptible people.

Are gallstones listed as a GLP-1 side effect?

Gallbladder-related events are listed as a possible adverse event in GLP-1 medication documentation, which makes sense because GLP-1 treatment can lead to substantial weight loss.

But important nuance:

Risk is not the same as certainty
Most people on GLP-1 do not develop gallstones
Speed of weight loss and personal risk factors matter

This is the difference between “associated with” and “directly caused by.”

What happened to me (quick version)

I lost 6 stone over 12 months on Mounjaro.

Then I developed symptoms I nearly dismissed:

Upper right abdominal pain
Back / shoulder blade pain
Episodes that didn’t behave like normal indigestion

Blood tests showed inflammation. Imaging confirmed obstruction. Emergency surgery followed.

Full timeline and symptoms here →

Who is most at risk of gallstones during GLP-1 weight loss?

People losing weight very rapidly
Anyone with previous gallstones or gallbladder “sludge” history
People with strong metabolic changes from obesity
Those on extreme calorie restriction alongside medication

In real life, it’s rarely “one thing.” It’s usually a combination.

Should you stop Mounjaro if you develop gallstones?

Do not stop prescribed medication without medical advice.

What happens next depends on:

How severe your symptoms are
Whether there’s infection or obstruction
Whether surgery is required
Your prescriber’s plan for risk vs benefit

Many people continue GLP-1 treatment after gallbladder removal under supervision.

Can you prevent gallstones during rapid weight loss?

There’s no guaranteed prevention method, but clinicians commonly discuss:

Avoiding crash dieting alongside GLP-1
Aim for steady loss when possible
Keeping diet consistent and not “yo-yoing” intake
Acting early if symptoms appear

If pain matches gallbladder patterns, getting assessed early is the safest move.

When to seek urgent medical help

Severe pain lasting more than 1–2 hours
Fever, chills, shaking
Yellowing of eyes/skin (jaundice)
Persistent vomiting
Worsening pain you can’t “ride out”

Optional digestion support (educational only)

During recovery and dietary changes, some people explore gentle digestion support — not as a treatment, but to support normal digestion while they work out what foods feel okay again.

Browse digestive support options at Lily & Loaf

Important: Supplements do not prevent gallstones and do not replace medical care. If you’re in severe pain or worried, seek urgent assessment.

FAQs

Can GLP-1 medications increase gallstone risk?

Rapid weight loss is a recognised risk factor. GLP-1 medications may increase risk indirectly in some people because they can lead to substantial weight loss.

Are gallstones common on Mounjaro?

They’re not common for most users, but gallbladder events are a recognised potential risk, especially during faster weight loss.

Is it the drug or the weight loss?

For many people the biggest driver is the speed of weight loss. Medication can contribute indirectly by accelerating fat loss.

Can you take Mounjaro after gallbladder removal?

Many people do, under medical supervision. Your clinician should guide timing and dosing after surgery.

What should I do if I have right-side pain on GLP-1?

If pain is severe, persistent, or comes with fever, vomiting or jaundice, seek urgent medical care.

Disclaimer: This article shares personal experience and educational context. It does not replace professional medical advice. If you have severe symptoms, fever, jaundice, persistent vomiting, or escalating pain, seek urgent medical care.