Mounjaro (tirzepatide).

What Mounjaro is

Mounjaro is the brand name for the medicine tirzepatide. It is a prescription-only medicine licensed in the UK for weight management (alongside a reduced-calorie diet and increased physical activity) in eligible adults, and separately for type 2 diabetes. It is given as a once-weekly injection under the skin using a pre-filled pen.

Generic (drug) name

Tirzepatide.

How it works, in plain English

Tirzepatide is a dual GIP/GLP-1 receptor agonist — it acts on two natural gut-hormone pathways (GLP-1 and GIP) that are involved in appetite and blood-sugar control. In practice it increases fullness, reduces appetite and slows stomach emptying, so many people feel satisfied with less food. It is started at a low dose and increased in steps to reduce side effects.

Who it may be considered for

Tirzepatide for weight management may be considered for adults following clinical assessment, generally where BMI is in a defined range together with weight-related health conditions. Eligibility is judged individually against the licensed indication — see eligibility & clinical assessment.

Clinical assessment required

Treatment is prescribed only after an in-person consultation covering your medical history, current medicines, previous weight-management attempts, contraindications and goals. Blood tests may be arranged where clinically indicated.

Important contraindications & precautions

Tirzepatide is not suitable for everyone. It is not used in pregnancy, when trying to conceive or while breastfeeding, and is used with particular caution in people with a history of pancreatitis or certain gastrointestinal conditions. Tell your clinician about all your medicines — doses of diabetes medicines such as insulin or a sulfonylurea may need adjusting.

Common side effects

Most side effects are gastrointestinal — nausea, vomiting, diarrhoea and constipation — usually mild-to-moderate and often easing with time. Reduced appetite, indigestion and injection-site reactions can also occur.

Important or serious adverse effects

• Acute pancreatitis — uncommon but serious; the MHRA strengthened warnings in 2026
• Gallbladder / biliary problems, which can occur with rapid weight loss
• Dehydration from vomiting or diarrhoea, which can affect the kidneys
• Low blood sugar, particularly if combined with insulin or a sulfonylurea
• Delayed stomach emptying — tell any surgeon or anaesthetist before an operation or procedure

Monitoring requirements & follow-up

If tirzepatide is prescribed, you are reviewed regularly — dose steps, weight and blood-pressure trends, tolerability and side effects are checked, and treatment is reviewed to decide whether to continue, adjust or stop. See treatment monitoring & follow-up.

Nutrition & lifestyle support

Tirzepatide is licensed for use alongside a reduced-calorie diet and increased physical activity. Protecting muscle and building sustainable habits are part of treatment, not an afterthought — see nutrition & lifestyle support.

When to seek medical advice

Seek advice for severe or persistent vomiting or diarrhoea, signs of dehydration, severe tummy pain, symptoms of gallstones (pain in the upper-right abdomen, fever, yellowing of the skin or eyes) or sudden vision changes. In an emergency call 999.

Is Mounjaro guaranteed if I ask for it?

No. Tirzepatide is prescription-only and is prescribed only where clinically appropriate after assessment. A particular medicine cannot be guaranteed before that assessment.

Is Mounjaro better than other treatments?

Not automatically. The best treatment varies between individuals and depends on your medical situation, suitability and tolerability. For some people a different medicine, or no medicine, is more appropriate.

Can I take Mounjaro in pregnancy?

No. It is not used in pregnancy, when trying to conceive or while breastfeeding, and should be stopped in advance of a planned pregnancy — ask your clinician about timing.

What does it cost?

Fees are the same across our weight-management service: an initial consultation is £150 (in person, 45 minutes) and ongoing monthly reviews are £99. Blood tests, where clinically indicated, are charged separately (lab fees from £150). Any medication cost is separate and depends on the treatment and dose that are clinically appropriate for you. See the weight-management pricing page for full details.

Sources & further reading. Information on this page is general and reflects UK guidance and product information, including the National Institute for Health and Care Excellence (NICE), the Medicines & Healthcare products Regulatory Agency (MHRA), the British National Formulary (BNF) and the approved Summary of Product Characteristics (SmPC) / patient information leaflet for each medicine. It does not replace advice from your own clinician. Always read the patient information leaflet supplied with your medicine.