Tirzepatide PL: reading the patient leaflet with confidence

What the tirzepatide PL actually is — and what it is not

Every box of Mounjaro contains a paper insert: the patient information leaflet, or PL. It exists because EU and UK licensing law requires manufacturers to translate the clinical Summary of Product Characteristics into language patients can reasonably understand. For tirzepatide, that SmPC is published in full on the Electronic Medicines Compendium (eMC), and the PL mirrors its core content.

The PL is not a treatment plan and it is not a dosing instruction from your prescriber. It tells you the range of doses the medicine comes in, the conditions it is licensed to treat, and the side effects that appeared in clinical trials and post-market reporting. What it cannot do is tell you which dose is right for your body, your other medicines, or your medical history, that is the prescriber's job, and it is why tirzepatide cannot legally be dispensed without a prescription.

Reading it before your first pen arrives is genuinely useful. You will recognise the pen format, know where the dose selector sits, and already have a mental note of the side effects worth monitoring. Patients who have read the leaflet tend to have sharper, more useful conversations with their clinical team. If anything in it raises questions specific to your situation, our aftercare team is available seven days a week to help you work out whether to call your GP or wait.

The eligibility and contraindication section: who the PL says should and should not use tirzepatide

The PL opens its indication section by describing Mounjaro as a treatment for weight management in adults with a BMI of 30 or above, or a BMI from 27 upward alongside at least one weight-related condition such as high blood pressure, type 2 diabetes, high cholesterol, or obstructive sleep apnoea. Those thresholds may be lower for some ethnic backgrounds under UK guidance, your prescriber applies the relevant adjustment during assessment.

The contraindications section is where many readers pause. The PL flags that Mounjaro should not be used in pregnancy, during breastfeeding, or when actively trying to conceive. It is not licensed for anyone under 18. A personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2 requires discussion with a doctor before any GLP-1 medicine is considered. The PL also asks patients to tell their prescriber about any history of pancreatitis or serious gastrointestinal conditions.

For women using oral contraceptive pills, the leaflet carries a specific note: because tirzepatide slows gastric emptying, pill absorption may be reduced for the first four weeks of treatment and for four weeks after each dose increase. Adding a non-oral method (condoms, for example) during those windows is the practical answer, as confirmed by NHS England's guidance on weight-management injections. If you are on HRT, the same guidance suggests discussing transdermal options with your doctor.

The side effects section: what the PL lists, and how to read it sensibly

Most of the PL's length is taken up by side effects. The list can look alarming at first glance, that is partly because it must include every event reported across thousands of trial participants, however rarely it occurred. Keeping some perspective helps.

The most common effects are gastrointestinal: nausea, loose stools, constipation, indigestion, and burping. These appear most often after starting and after moving to a higher dose, and for most people they ease within a week or two as the body adjusts. Fatigue and headache are also listed among the more frequent reports. The NHS tirzepatide medicine page summarises these in accessible terms and is worth bookmarking alongside your PL.

The PL also lists signs that need prompt medical attention. Severe abdominal pain that spreads to the back, with or without vomiting, can be a sign of pancreatitis, an infrequent but serious condition. The MHRA highlighted acute pancreatitis in a Drug Safety Update for GLP-1 medicines in January 2026, reinforcing that patients and prescribers should take this symptom seriously. If you experience it, stop the injection and seek medical help rather than waiting for your next appointment. Gallbladder problems, dehydration from persistent vomiting or diarrhoea, and any signs of an allergic reaction also warrant the same response. You can report any suspected side effect directly through the MHRA Yellow Card scheme.

Dose schedule, storage, and the gaps the PL leaves for your prescriber to fill

The PL sets out the licensed titration ladder: treatment begins at 2.5 mg, with increases typically every four weeks, up through 5, 7.5, 10 mg, a dose that our tirzepatide 10 page covers in more detail, 12.5, and 15 mg, with higher-strength options such as tirzepatide 30 explained on the relevant page. Reading that sequence can make the process feel mechanical, as if you simply climb the steps in order. In practice, your prescriber reviews your progress before each increase, and the timing or the ceiling may be adjusted based on how you are responding. Evidence reviews your prescriber requests before dose increases are a safety step, not a bureaucratic hurdle. If you are considering what private clinical review looks like at each stage, the Mounjaro treatment page covers the process in detail.

On storage: the PL gives precise temperature windows and room-temperature limits that vary slightly between formulations. Rather than repeat those figures here (where they could drift out of date if the SmPC is updated) refer directly to the leaflet inside your specific pen. The broad principle is refrigeration between 2°C and 8°C, away from the freezer compartment. One practical note: the pen sits neatly in the fridge door, though the door can be warmer than the shelf on hot days, the middle shelf is safer in summer.

The injection sites listed are the abdomen, the front of the thigh, and the upper arm. Rotating between them reduces the chance of localised skin reactions. If you are new to self-injection and want more detail on technique, our guide to tirzepatide injection sites walks through the process step by step. For background on how tirzepatide works and what the treatment involves, our tirzepatide page addresses the common questions around how the medicine fits into a broader weight management plan. For background on how tirzepatide compares to other weight-loss medicines available in the UK, the Mounjaro or tirzepatide page addresses the common questions around naming and options. When you are ready to talk to a prescriber about whether this treatment fits your situation, check your eligibility with our clinical team.