Who Shouldn't Take Mounjaro: Contraindications and Cautions Explained

You've been told Mounjaro might work for you, but your GP hesitated

That hesitation usually comes from somewhere specific. GPs and independent prescribers are trained to weigh up a set of hard stops before issuing tirzepatide. If you want a clear overview of who should not take Mounjaro, the clearest hard stops involve thyroid history: anyone with a personal history of medullary thyroid carcinoma (a particular type of thyroid cancer), or a family history of it, should not take Mounjaro. The same applies if you have been diagnosed with Multiple Endocrine Neoplasia syndrome type 2, a genetic condition that raises thyroid cancer risk. These aren't precautions to discuss; they are contraindications, meaning the medicine is off the table entirely.

Pancreatitis is another firm line. If you have had acute or chronic pancreatitis in the past, a prescriber will not start tirzepatide without very careful consideration, and in many cases it will not be prescribed at all. The MHRA issued a Drug Safety Update in January 2026 specifically flagging acute pancreatitis as a known, if infrequent, risk with GLP-1 medicines, severe stomach pain radiating to the back, with or without vomiting, needs urgent medical attention. That context matters when your history already includes it.

Significant gastroparesis or inflammatory bowel disease also gives prescribers pause, because tirzepatide slows gastric emptying further. If you have had bowel surgery or live with a condition that already affects how your gut moves food, that conversation with a clinician isn't optional, it is the assessment.

Pregnancy, breastfeeding, and planning to conceive

This is unambiguous. Mounjaro is not recommended during pregnancy. It is not recommended while breastfeeding. And it should be stopped before trying to conceive, with a wash-out period in between, the MHRA and NHS both advise using reliable contraception throughout treatment for this reason. The NHS medicines page for tirzepatide sets this out plainly, and it reflects the SmPC (the medicine's official prescribing information).

For women using the oral contraceptive pill, there is an additional practical issue. Tirzepatide delays how quickly your stomach empties, which can reduce how much of a once-daily pill is absorbed. Understanding when you should take Mounjaro matters here, because NHS guidance is clear: add a barrier method (condoms, for example) for the first four weeks of Mounjaro treatment and for four weeks after every dose increase. There is no equivalent concern documented for semaglutide, but for tirzepatide the recommendation is firm. If you rely on the pill and you are considering this treatment, it is worth reading the full picture on whether Mounjaro is right for your situation before you start.

Mounjaro is not licensed for anyone under 18. Full stop.

Medical histories that need a proper conversation, not a self-check

Beyond the hard contraindications, a number of conditions place someone in a category where the prescriber needs more information before deciding. Diabetic retinopathy (damage to blood vessels at the back of the eye) can worsen if blood sugar changes rapidly; anyone with existing retinal disease should flag it. Kidney function matters too, because severe dehydration from GI side effects can stress the kidneys; anyone with pre-existing kidney problems should be open about that at consultation.

Certain medicines interact with tirzepatide in ways that matter. Insulin and other glucose-lowering drugs carry hypoglycaemia risk when combined with it. And because tirzepatide slows how quickly food reaches the small intestine, the timing and absorption of oral medicines taken alongside it can shift. This is one reason a thorough, human-led consultation (not an automated form) matters for this kind of prescription. At nume, a GPhC-registered Independent Prescriber personally reads every consultation the same day, rather than relying on an algorithm to triage responses.

If you are not sure whether your history makes you a candidate, the honest answer is: you need a clinical assessment, not a webpage. Our frequently asked questions cover some of the common scenarios, but the assessment is where the real answer lives. You can also read about how our clinical service works before you decide whether to go ahead.

What a legitimate assessment actually checks, and what that protects you from

A proper Mounjaro consultation reviews your BMI, your weight-related conditions, your current medications, your thyroid and pancreatic history, your reproductive status, your kidney and liver function, and any relevant family history. It also checks your identity and verifies your current weight. At nume, that includes photo-ID verification and live weight confirmation on video, not because we are being awkward, but because a prescriber cannot safely make a clinical decision without knowing who they are treating and what they actually weigh. The pen sitting in your fridge door after delivery represents a real clinical decision made about a real person.

For a broader look at who Mounjaro is suitable for, including BMI thresholds and the weight-related conditions that qualify, the tirzepatide overview page covers that in detail. If you are already weighing up whether tirzepatide or semaglutide fits your situation better, our weight-loss treatment overview compares the options clearly. And if you have already done your research and want a prescriber to assess you properly, you can start a free consultation with our team today, one of our prescribers will review your answers the same day and let you know where you stand.