Who Can't Have Mounjaro: Contraindications the Prescriber Checks First

The biggest misconception: thinking it's only about BMI

A lot of people assume that once their BMI clears the threshold, the prescription is a formality. It isn't. BMI is the starting point for eligibility, adults with a BMI of 30 or above, or 27 or above with a qualifying weight-related condition, may meet the basic licensed criteria. But the prescriber is also looking at your medical history, your current medicines, and a range of specific conditions that can make tirzepatide the wrong choice regardless of what the scales say.

That misconception is an understandable one, and letting it go is genuinely important: being turned down isn't a failing, it's the system working as it should. If you'd like a clearer sense of who the licensed criteria are written for, our page on who can have Mounjaro covers the positive case in full.

Below are the specific categories the prescriber will screen for, and where the answer may well be that Mounjaro is not the right medicine for you right now.

Absolute contraindications: cases where Mounjaro is not prescribed

Some exclusions are clear-cut. The medicine's licensed prescribing information sets out a small number of conditions where tirzepatide is contraindicated, meaning it should not be used at all.

The clearest is a personal or family history of medullary thyroid carcinoma (MTC). Tirzepatide activates GIP and GLP-1 receptors, and animal studies showed thyroid C-cell effects; while a direct human link has not been established, the risk cannot be excluded and the contraindication stands. A related condition, Multiple Endocrine Neoplasia type 2 (MEN2) (which carries an elevated MTC risk) falls into the same category.

Anyone with a known allergy or hypersensitivity to tirzepatide or any component of the pen cannot take it. This includes people who have previously had a serious allergic reaction to the medicine.

These aren't grey areas, and our page on who can't take Mounjaro gives a fuller picture of the people the licensed criteria are designed to exclude. A prescriber who identifies any of them will not issue a prescription, and a responsible service will screen for them at the consultation stage. You can see how our pharmacy and clinical team approach that process.

Conditions that usually mean Mounjaro is not suitable

Beyond the hard contraindications, a wider group of medical circumstances will typically lead a prescriber to advise against tirzepatide, or to conclude that the risks outweigh the benefits for that individual.

Pancreatitis is the most significant. In January 2026, the MHRA issued a Drug Safety Update highlighting acute pancreatitis as an infrequent but potentially serious risk with GLP-1 class medicines; anyone with a history of the condition will need to discuss it with a prescriber, and many will be found unsuitable. Severe, persistent stomach pain (especially if it reaches the back) is the symptom to treat as urgent.

People with significant gastroparesis or inflammatory bowel disease are generally not candidates: tirzepatide slows gastric emptying, which can worsen these conditions. Severe kidney or liver impairment also requires careful assessment, and in more advanced cases is likely to rule treatment out.

Active eating disorders (including but not limited to restrictive disorders) are a clinical reason to pause. Tirzepatide reduces appetite substantially, and using it without appropriate mental-health support in that context can be harmful.

For a broader look at the BMI and health criteria a prescriber considers together, the BMI guidance for Mounjaro page goes into more detail.

Circumstances where Mounjaro is not used: pregnancy, breastfeeding and under-18s

Tirzepatide is not licensed for anyone under 18. The trials that established its safety and effectiveness enrolled adults, and there is no evidence base to support use in younger people.

Use during pregnancy is not recommended, and neither is starting or continuing it while breastfeeding. Anyone planning to become pregnant should stop treatment and discuss timing with their prescriber, there is a wash-out period to consider before trying to conceive. The MHRA advises using reliable contraception while on treatment; women taking the oral contraceptive pill should add a non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because tirzepatide's effect on gastric emptying may reduce pill absorption.

These are not unusual restrictions for a prescription medicine in this class. The full Mounjaro overview covers how the medicine works and what the treatment process looks like for people who are suitable.

Medicines that may affect whether tirzepatide is appropriate

Drug interactions are part of every prescriber's assessment. Two categories get particular attention.

If you take insulin or other glucose-lowering medicines for type 2 diabetes, adding tirzepatide changes how those medicines behave. Doses of insulin or sulfonylureas often need adjusting to avoid hypoglycaemia. This isn't an automatic bar to treatment, but it does require careful clinical management and honest disclosure of all current medicines.

As noted above, women on oral contraceptives need to know about the pill-absorption interaction, not because it rules Mounjaro out, but because a backup method is necessary during dose changes.

Any medicine that also slows gastric emptying, affects blood pressure significantly, or interacts with the same metabolic pathways should be declared in full at consultation. The prescriber's job is to weigh all of that. Curious about what the process looks like from the start? Our page on how to get Mounjaro explains the steps. And if you're weighing up what private treatment actually costs once it's confirmed you're eligible, the Mounjaro cost page sets out what a legitimate private prescription includes.

If any of this raises questions about your own situation, the right next step is a clinical conversation. Speak to our prescribers through a free consultation, they review every case personally, the same day.