Prescription treatment information
Mounjaro (tirzepatide): treatment information
Factual UK information about what Mounjaro is, who may be considered for treatment, how it is taken and the safety information patients should know.
This page does not recommend Mounjaro over other approaches to weight management.
Information, not individual medical advice
Mounjaro is not suitable for everyone. Whether prescription treatment is appropriate—and which option is most suitable—must be decided following a clinical assessment of your health, medicines, circumstances and goals. Always follow the instructions supplied by your prescriber and in the patient information leaflet.
Understanding the treatment
What is Mounjaro?
Mounjaro is the brand name for tirzepatide. It is a prescription-only medicine that acts on GIP and GLP-1 receptors involved in appetite, food intake and blood-glucose regulation.
For weight management, it is used alongside a reduced-calorie diet and increased physical activity. It does not replace nutrition, movement and ongoing clinical review.
Licensed use for adult weight management
The UK product information states that Mounjaro may be used for weight management, including weight loss and weight maintenance, in adults with an initial BMI of:
Classed as obesity in the licensed indication.
Where at least one weight-related health condition is also present, such as high blood pressure, abnormal blood fats, obstructive sleep apnoea, cardiovascular disease, prediabetes or type 2 diabetes.
Meeting a BMI threshold does not automatically make treatment suitable. A full clinical assessment is still required.
How it works
Supporting appetite regulation and fullness
Tirzepatide acts on two hormone pathways. Its effects vary between individuals, and no particular amount of weight loss can be guaranteed.
Appetite
It can reduce appetite and food cravings, which may make a reduced-calorie eating pattern easier to follow.
Fullness
It slows gastric emptying and may help you feel fuller for longer after eating.
Blood-glucose regulation
It also affects insulin and glucagon responses, which are involved in controlling blood-glucose levels.
Administration and dosing
How Mounjaro is taken
Mounjaro is injected under the skin once each week. It may be administered in the abdomen or thigh, or in the back of the upper arm by another person.
- Use on the same day each week where possible
- It can be taken at any time of day, with or without food
- Rotate the injection site with each dose
- Each UK KwikPen contains four weekly doses
Licensed adult dose progression
| Strength | Place in the dose schedule |
|---|---|
| 2.5 mg | Starting dose once weekly for the first 4 weeks |
| 5 mg | Usual next dose; also a recommended maintenance dose |
| 7.5 mg | Possible dose-escalation step where clinically appropriate |
| 10 mg | Recommended maintenance-dose option |
| 12.5 mg | Possible dose-escalation step where clinically appropriate |
| 15 mg | Recommended maintenance-dose option and maximum adult weekly dose |
If an increase is needed, the licensed schedule uses 2.5 mg increments after at least 4 weeks on the current dose. Dose increases are not automatic and should only be made on the prescriber’s advice.
Tolerability
Common side effects
Digestive side effects are the most frequently reported. They are often more noticeable when treatment starts or the dose increases, and may lessen over time.
Tell your prescriber about side effects, especially if they are persistent, worsening or affecting your ability to eat and drink normally.
Side effects can include
This is not a complete list. Read the current patient information leaflet supplied with your medicine for all recognised side effects and advice.
Preventing dehydration mattersVomiting and diarrhoea can lead to fluid loss and may affect kidney function. Keep hydrated where you can and seek clinical advice if symptoms are significant or persistent.
Safety information
When to seek urgent medical help
Some symptoms need prompt assessment. Do not wait for a routine treatment review if you develop any of the following.
Possible pancreatitis
Persistent, severe abdominal pain, which may spread through to the back, with or without vomiting. Stop using Mounjaro and seek immediate medical attention.
Serious allergic reaction
Difficulty breathing, rapid swelling of the lips, tongue or throat, or collapse. Call 999 for emergency help.
Severe dehydration
Repeated vomiting or diarrhoea with inability to keep fluids down, very little urine, marked dizziness, confusion or fainting needs urgent clinical advice.
Unsure what to do? Contact your prescriber or NHS 111 for urgent advice. Call 999 or attend A&E for a medical emergency.
Before treatment
What your prescriber needs to know
Your clinical assessment should cover your health history, current medicines, previous weight-management treatment and any symptoms that could affect safe prescribing.
Pancreas or gallbladder problemsIncluding previous pancreatitis, gallstones or gallbladder inflammation.
Digestive conditionsParticularly severe gastrointestinal disease or severe gastroparesis.
Diabetes treatmentEspecially insulin or a sulphonylurea, which can increase the risk of low blood sugar when combined with tirzepatide.
Diabetic eye diseaseSome patients require closer monitoring of diabetic retinopathy.
Kidney or liver problemsSevere impairment may require additional caution and monitoring.
Other oral medicinesDelayed stomach emptying can affect the timing of absorption, particularly for medicines needing close monitoring or rapid action.
Planned surgery or sedationTell the clinical team that you use Mounjaro before a procedure involving anaesthesia or deep sedation.
Allergies and previous reactionsMounjaro must not be used if you are allergic to tirzepatide or another ingredient in the product.
Pregnancy, contraception and breastfeeding
Mounjaro should not be used during pregnancy. If you are planning a pregnancy, current UK product information advises stopping tirzepatide at least one month beforehand. Contact your prescriber straight away if you become pregnant during treatment.
If you use an oral contraceptive pill, switch to a non-oral method or add a barrier method for 4 weeks after starting Mounjaro and for 4 weeks after every dose increase. Discuss the most appropriate contraception with a healthcare professional.
If you are breastfeeding or planning to breastfeed, tell your prescriber so the current evidence and your individual circumstances can be assessed.
Common questions
Mounjaro treatment questions
These answers are general. Your prescriber’s instructions and the leaflet supplied with your medicine take priority.
View the factual treatment price list →What should I do if I miss a dose?
If it is 4 days or less since the missed dose, use it as soon as you remember. If more than 4 days have passed, skip it and use the next dose on your usual scheduled day. Do not take two doses less than 3 days apart, and do not double the dose.
Can I increase my dose every month?
Dose increases are not automatic. You should remain on each dose for at least 4 weeks, and an increase should only occur if your prescriber considers it appropriate based on response, side effects and safety.
Can I switch from another weight-management medicine?
Switching requires a clinical assessment. Do not overlap treatments, change the timing or calculate a new dose yourself. Your prescriber will consider your previous medicine, last dose, side effects and relevant health information.
Can Mounjaro be used with insulin or diabetes tablets?
Sometimes, but the combination needs review. Using tirzepatide with insulin or a sulphonylurea can increase the risk of low blood sugar, and the diabetes treatment may need adjustment and monitoring.
Does everyone progress to 15 mg?
No. The maximum dose is not automatically the most suitable dose. The appropriate maintenance dose is based on response, tolerability and clinical review.
Where can I find the full patient leaflet?
The current electronic Medicines Compendium patient leaflet is linked in the sources below. You should also read the leaflet supplied with every pen.
Clinical authorship
Sources and further reading
- 1Mounjaro KwikPen Summary of Product Characteristics — electronic Medicines Compendium
- 2Mounjaro KwikPen Patient Information Leaflet — electronic Medicines Compendium
- 3NICE TA1026: Tirzepatide for managing overweight and obesity
- 4MHRA: GLP-1 medicines for weight loss and diabetes—what you need to know
TheraVita weight management
Learn about the clinical service
Explore TheraVita’s pharmacist-led weight-management programme, including clinical assessment, personalised lifestyle support and ongoing reviews.
Treatment options are only considered following an individual clinical assessment.