Can Mounjaro Cause Kidney Stones? What the Evidence Actually Shows

What the current evidence says about Mounjaro and kidney stone risk

Across the SURMOUNT clinical trial programme, which enrolled thousands of adults with obesity, kidney stone formation was not identified as a safety signal for tirzepatide. The medicine's Summary of Product Characteristics, published on the electronic Medicines Compendium, does not list nephrolithiasis among its known adverse effects. The MHRA has not issued a Drug Safety Update linking tirzepatide to kidney stones.

So the short answer to whether Mounjaro directly causes kidney stones is: based on the evidence available right now, no. That does not mean zero risk for every individual (kidney stone formation is influenced by fluid intake, diet, urine composition and personal predisposition) but the medicine itself has not been identified as a cause, and our page on whether tirzepatide causes kidney stones walks through exactly why the evidence points in that direction.

If you want a deeper read on how tirzepatide interacts with renal physiology more broadly, the Mounjaro and kidney stones page covers the biochemistry in more detail. The picture for kidney function generally is addressed on our Mounjaro and kidney damage page, which draws on the same clinical dataset.

The dehydration link: where the real indirect risk sits

Here is where the nuance matters. Nausea, vomiting and diarrhoea are among the most commonly reported side effects of tirzepatide, particularly in the first few weeks after starting or after a dose increase. These symptoms, if significant, reduce the amount of fluid your body retains. Chronic low fluid intake is one of the clearest modifiable risk factors for kidney stones, concentrated urine gives minerals more opportunity to crystallise.

This is not a risk unique to Mounjaro; it applies to any condition or medicine that causes GI fluid loss. But it does mean that if you are prone to kidney stones, or have had one before, keeping up fluid intake during the adjustment period deserves real attention. A rough practical anchor: if your urine is pale yellow rather than dark, you are broadly on track. If you are struggling to drink because of persistent nausea, that is worth raising with your prescriber, not something to push through quietly.

People who are wondering how alcohol affects hydration on Mounjaro should factor that in too, alcohol is itself dehydrating, and that stacks.

If you have a history of kidney stones: the decision your prescriber needs to make

Having had a kidney stone in the past does not mean Mounjaro is off the table. Most prescribers will want to know the history: what type of stone it was (calcium oxalate, uric acid, struvite and cystine stones have different dietary and metabolic drivers), how recent, whether there is an underlying metabolic condition, and how you currently manage your fluid intake, all of which is explored in more detail on our page covering whether you can take Mounjaro if you have kidney stones.

Uric acid stones, for example, are more common in people with obesity, insulin resistance and metabolic syndrome, exactly the population that tirzepatide is licensed to treat. Significant weight loss can actually improve the metabolic conditions that predispose some people to uric acid stones. Whether treatment is net beneficial for you specifically is not something a content page can resolve. It is the kind of question that needs a prescriber who has seen your medical history.

At nume, a GPhC-registered Independent Prescriber (a real clinician, not automated triage) reads every consultation before anything is approved or dispatched. If you have a kidney history that needs discussing, that is the place to raise it. Our clinical team treats these conversations as part of the review, not a complication.

When to get medical help, and how to report concerns

If you are already taking Mounjaro and develop any of the following, seek urgent medical attention rather than waiting for a routine appointment: severe pain in your side or lower back that does not ease with position changes, blood in your urine, pain when urinating, or persistent vomiting that is preventing you from keeping fluids down. These could indicate a kidney stone, a urinary tract problem, or dehydration that needs prompt assessment.

Suspected side effects can be reported to the MHRA directly via the Yellow Card scheme, the scheme exists precisely so that rare or emerging patterns get picked up in real-world use, even when they were not identified in trials. If you are uncertain about a symptom, our aftercare team is available seven days a week. You can reach us through the contact page.

For a broader look at how tirzepatide interacts with renal health, including what the trial data says about kidney function markers, our page on the relationship between tirzepatide and kidney stones approaches the same question from the pharmacology angle. And if you are considering starting treatment or want to check whether your history affects your eligibility, you can check your eligibility with a free consultation, there is no obligation, and your answers go straight to a prescriber.