Mounjaro (tirzepatide) is a prescription medicine licensed in the UK for treating type 2 diabetes mellitus in adults. It is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist, helping to control blood glucose and promote weight loss. In the UK, tirzepatide for weight management is marketed as Zepbound. Understanding who Mounjaro is for, how it works, and whether you meet the eligibility criteria is essential before starting treatment. This article explains who can be prescribed Mounjaro, how to access it via the NHS or privately, and what to consider when discussing this treatment with your healthcare provider.

What Is Mounjaro and How Does It Work?

Mounjaro (tirzepatide) is a prescription medicine licensed in the UK for the treatment of type 2 diabetes mellitus. In the UK, tirzepatide for weight management is marketed under the brand name Zepbound. Mounjaro is administered as a once-weekly subcutaneous injection and belongs to a novel class of medicines known as dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists.

The mechanism of action of Mounjaro involves mimicking two naturally occurring incretin hormones: GIP and GLP-1. These hormones are released by the gut in response to food intake and play crucial roles in regulating blood glucose levels. By activating both GIP and GLP-1 receptors, tirzepatide enhances insulin secretion from the pancreas when blood glucose is elevated, suppresses the release of glucagon (a hormone that raises blood sugar), slows gastric emptying, and reduces appetite. This dual action helps improve glycaemic control in people with type 2 diabetes and promotes weight loss.

Clinical trials have demonstrated that Mounjaro can lead to significant reductions in HbA1c (a marker of long-term blood glucose control) and substantial weight loss compared to placebo and other diabetes medications. The weight loss effect is thought to result from reduced calorie intake due to increased satiety and delayed gastric emptying.

Mounjaro treatment typically starts at 2.5 mg once weekly, with gradual dose escalation at intervals of at least 4 weeks, up to a maximum of 15 mg once weekly. This gradual titration helps minimise gastrointestinal side effects and optimise therapeutic benefit. It is important to note that Mounjaro is not insulin and is not indicated for the treatment of type 1 diabetes or diabetic ketoacidosis.

Importantly, Mounjaro delays gastric emptying and can reduce the absorption of oral medications, including oral contraceptives. Women using oral contraceptives should consider additional contraceptive methods for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.

Who Is Mounjaro Prescribed For in the UK?

In the UK, Mounjaro is licensed for the treatment of type 2 diabetes in adults whose blood glucose is inadequately controlled despite lifestyle modifications and, in many cases, other antidiabetic medications. It may be used as monotherapy when metformin is contraindicated or not tolerated, or more commonly as part of combination therapy alongside metformin, SGLT2 inhibitors, or insulin.

The National Institute for Health and Care Excellence (NICE) has issued guidance on the use of tirzepatide for type 2 diabetes (TA849), recommending it as an option for adults when certain glycaemic and treatment criteria are met. NICE guidance for GLP-1 based therapies (including tirzepatide) generally recommends their use in people with type 2 diabetes who have a body mass index (BMI) of 35 kg/m² or higher and specific problems associated with high weight, or who have a BMI below 35 kg/m² and for whom insulin therapy would have significant occupational implications or weight loss would benefit other obesity-related comorbidities.

For weight management, tirzepatide (marketed as Zepbound in the UK) is indicated for adults with a BMI of 30 kg/m² or greater (obesity), or a BMI of 27 kg/m² or greater (overweight) in the presence of at least one weight-related comorbidity such as hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease. It should be used alongside a reduced-calorie diet and increased physical activity. NICE has recommended tirzepatide for weight management (TA923) in adults with at least one weight-related comorbidity who are referred to specialist Tier 3 or 4 weight management services. NHS availability is being implemented gradually, with prioritisation for those at highest clinical need.

Mounjaro is not suitable for everyone. According to the UK Summary of Product Characteristics, it is contraindicated in individuals with hypersensitivity to tirzepatide or any of the excipients. Caution is advised in people with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2. Tirzepatide should be avoided during pregnancy and women should stop treatment at least 1 month before a planned pregnancy. Breastfeeding is not recommended during treatment. Additional caution is advised in people with severe gastrointestinal disease, a history of pancreatitis, or severe renal impairment.

How to Know If Mounjaro Is Right for You

Determining whether Mounjaro is appropriate for you requires a comprehensive assessment by a healthcare professional, typically your GP, practice nurse, or a specialist in diabetes or obesity medicine. Several factors will be considered, including your medical history, current medications, BMI, blood glucose control (if you have diabetes), and the presence of any weight-related health conditions.

If you have type 2 diabetes, your clinician will review your recent HbA1c levels, your response to existing treatments, and whether you meet the clinical criteria outlined in NICE guidance. They will also assess your cardiovascular risk, kidney function, and any history of diabetic complications. If your diabetes is not adequately controlled despite optimal use of other medications, and you meet the eligibility criteria, Mounjaro may be considered as an addition or alternative to your current regimen.

People with pre-existing diabetic retinopathy should be aware that rapid improvement in blood glucose control may temporarily worsen retinopathy. If you have diabetic retinopathy and start Mounjaro, you should seek prompt medical advice if you notice any changes in your vision.

For those seeking tirzepatide primarily for weight management, your healthcare provider will evaluate your BMI, the presence of comorbidities such as high blood pressure or sleep apnoea, and your previous attempts at weight loss through lifestyle changes or other interventions. A discussion about realistic weight loss goals, potential side effects, and the importance of ongoing dietary and physical activity modifications is essential. Your clinician will also screen for any conditions that require caution with tirzepatide use.

Common side effects of Mounjaro include nausea, vomiting, diarrhoea, constipation, abdominal pain, and reduced appetite. These are usually mild to moderate and tend to improve over time, particularly with gradual dose escalation. Rare but serious adverse effects include pancreatitis (watch for severe, persistent abdominal pain that may radiate to the back), gallbladder disease, acute kidney injury (often secondary to dehydration from gastrointestinal symptoms), hypersensitivity reactions (such as swelling, rash, or breathing difficulties), and hypoglycaemia (especially when used with insulin or sulfonylureas). If you experience concerning symptoms, contact your GP or seek medical attention promptly.

It is also important to consider practical factors, such as your willingness and ability to self-administer weekly injections, the cost (if accessing privately), and your commitment to the necessary lifestyle changes that underpin successful treatment with Mounjaro.

If you experience any suspected side effects from Mounjaro, you can report them via the MHRA Yellow Card Scheme (website or app), which helps monitor the safety of medicines in the UK.

Getting Mounjaro: NHS and Private Prescriptions

Access to Mounjaro in the UK depends on whether you are seeking treatment via the NHS or through a private prescription, and whether the indication is for type 2 diabetes or weight management.

NHS access for type 2 diabetes is guided by NICE recommendations (TA849). If you meet the clinical criteria, your GP or diabetes specialist can prescribe Mounjaro on the NHS. However, availability may vary by local integrated care board (ICB) formularies and prescribing policies. Some areas may require prior approval or specialist initiation before GPs can continue prescribing. It is advisable to discuss your eligibility and local pathways with your healthcare team.

For weight management, NHS access to tirzepatide (Zepbound) is more restricted. NICE has recommended tirzepatide (TA923) as an option for weight management in eligible adults, but only when prescribed within specialist Tier 3 or 4 weight management services. Implementation is being phased, with priority given to those with the highest clinical need. The NHS is also rolling out access gradually due to supply constraints and the need to ensure appropriate clinical support. If you are interested in tirzepatide for weight loss, ask your GP about local referral pathways to specialist obesity services.

Private prescriptions offer an alternative route, particularly for weight management. Numerous private clinics and online prescribing services in the UK offer tirzepatide, typically following a remote or in-person consultation with a prescriber. Costs vary but generally range from approximately £150 to £300 per month, depending on the dose, provider, and current market availability. It is crucial to use a registered and regulated service, such as those registered with the Care Quality Commission (CQC) in England, and to ensure that the prescriber is a UK-registered doctor, nurse, or pharmacist prescriber.

Important safety advice: Whether accessing Mounjaro via the NHS or privately, you should have regular follow-up appointments to monitor your response, manage side effects, and adjust treatment as needed. Dose escalations should occur at intervals of at least 4 weeks. Blood tests to check kidney function, and in people with diabetes, HbA1c monitoring (typically every 3-6 months), are recommended. If you experience severe side effects or your condition does not improve, your prescriber may advise stopping treatment or switching to an alternative. Always inform your healthcare provider of all medications and supplements you are taking, as interactions can occur, particularly with insulin and other glucose-lowering drugs.

Frequently Asked Questions