Gemma Collins shares fear that Mounjaro use led to ‘agonising’ unexpected side effect

Gemma Collins has revealed that she has decreased her Mounjaro dosage amid concerns the medication triggered an 'agonising' health condition.

Given that it's very much been the standout dieting trend of 2025, you're probably well aware by now about how Mounjaro works.

One of two GLP-1 and GIP receptor agonist drugs licensed for weight loss in the UK, Mounjaro has been used by celebrities such as Jeremy Clarkson, Meghan Trainor and influencer Tana Mongeau in recent months.

And with at least 500,000 people in the UK prescribed either Mounjaro or similar GLP-1 drug Wegovy by their doctor, chances are someone you know is likely using it as well.

For the majority of users, the drug has been life-changing; however, like all medication, Mounjaro is not without side effects.

Mounjaro has become increasingly popular for aiding weight-loss (Matthew Horwood/Getty Images)

Common side effects typically include nausea, vomiting, constipation and diarrhoea, but for Collins, her Mounjaro journey may have triggered a rare and 'agonising' complication.

During a recent interview with MailOnline, the 44-year-old revealed that she'd had to reduce her dosage after losing three stone - supposedly due to developing gallstones.

"I had a little gallbladder attack. I'm not sure if it's linked, they say it can be linked, it's not always the case, so I've had to slow down on it all for a bit," she explained.

According to the NHS, the condition is where small stones develop in the gallbladder. If one of the stones blocks a bile duct in the gallbladder, it can lead to excruciating stomach pain – which is what Collins experienced.

"We were going away for Rami's [Hawash, her partner] 50th and I was in excruciating pain," she said.

"I fell to the floor, whilst he was going round the track. And I was like, whoa, I'm in pain. And then I was thinking I'm gonna have to go and sit in A&E.

"I called my doctor and he said, 'let me come to your house scan you'. When he scanned me, it was gallstones.

Reality star Gemma Collins revealed her gallstones may be linked to using Mounjaro (Instagram/@gemmacollins)

"'But gallstones, this is where I'm not 100 per cent convinced at the minute, gallstones, everyone can have gallstones and they can flare up at any time," she continued.

"You know, I was in such pain, but I've got the medication at the minute that's helping me."

Can Mounjaro cause gallstones?

According to Boots, gallstones impact one in 100 people using Mounjaro, with the main cause for the condition being the rapid weight loss which the drug causes. Meanwhile, Mounjaro manufacturer Eli Lilly has acknowledged gallbladder-related side effects as a possibility when taking the tirzepatide medication. "Gallbladder problems have happened in some people who use Mounjaro," advice for side effects listed on Eli Lilly reads.

"Tell your healthcare provider right away if you get symptoms of gallbladder problems, which may include pain in your upper stomach (abdomen), fever, yellowing of skin or eyes (jaundice), and clay-coloured stools."

LADbible has approached Eli Lilly for comment.