What is Mounjaro?
Mounjaro is the brand name for tirzepatide, a prescription only injection taken once a week. In the UK the Mounjaro weight loss injection is also licensed for type 2 diabetes, so one medicine has two uses. This guide explains what Mounjaro is in the UK, what is in the pre-filled pen, how it works, who can and cannot take it, and how it is prescribed. It informs; it does not replace advice from your prescriber.
Based on the UK Mounjaro summary of product characteristics and patient leaflet
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Mounjaro at a glance
A quick summary of what Mounjaro is, before the detail below.
| Question | Short answer |
|---|---|
| Brand name | Mounjaro |
| Generic name | Tirzepatide, the name of the active substance |
| Type of medicine | A dual agonist, acting on the GIP and GLP-1 receptors |
| How it is given | An injection under the skin, once a week, from a pre-filled pen |
| Licensed uses in the UK | Type 2 diabetes, and weight management |
| How you get it | Prescription only. A prescriber decides, and a registered pharmacy supplies it |
What is Mounjaro used for?
The licence covers two uses, and the same medicine is used for both. Which one applies to you depends on why your prescriber is offering it.
Mounjaro for type 2 diabetes
In type 2 diabetes, Mounjaro is used alongside diet and exercise to bring blood sugar down. It helps the body release insulin when blood sugar is high and slows how quickly food leaves the stomach. It is not insulin, and it is a different kind of medicine from it.
Mounjaro for weight management
People often call it the Mounjaro weight loss jab, or simply the weight loss injection. The licensed term is weight management. It is used with a reduced calorie diet and more physical activity, for adults who meet the weight and health conditions in the section on who can take Mounjaro below. What is Mounjaro weight loss treatment, then? It is one part of a plan, not a stand alone fix.
How does Mounjaro work?
Tirzepatide is a long acting GIP and GLP-1 receptor agonist. In plain words, it copies two hormones your gut releases after a meal. Because it acts on both, it is called a dual agonist, and the Mounjaro GLP-1 and GIP action is what sets it apart from medicines that copy GLP-1 alone.
- Blood sugar. It helps the body release insulin when blood sugar is high, and lowers the sugar made by the liver.
- Appetite. It acts on the parts of the brain that control hunger, so many people feel full sooner and eat less.
- Digestion. It slows how fast the stomach empties. This is also why stomach side effects are the ones people notice most.
Two hormones do not automatically mean a better result for every person. Your prescriber chooses a medicine by looking at your health, not by the number of receptors it acts on.
What is in Mounjaro?
What is Mounjaro tirzepatide? It is the active substance. It comes as a clear, colourless to slightly yellow liquid in a pre-filled pen, with no powder to mix.
| Pen fact | What the UK summary of product characteristics says |
|---|---|
| Active substance | Tirzepatide |
| Form | Solution for injection |
| The pen | A multiple dose pre-filled pen, called the KwikPen |
| Doses in one pen | 4 weekly doses, each of 0.6ml |
| Strengths | 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg, one strength per pen |
| Other ingredients | Listed in the leaflet. Benzyl alcohol is one of them |
Is Mounjaro the same as tirzepatide?
Yes. Tirzepatide is the generic name, which is the name of the medicine itself. Mounjaro is the brand name, also called the trade name, chosen by the company that makes it. A licensed Mounjaro pen is not the same as an unlicensed product sold as tirzepatide, so check with a pharmacist if you are unsure what you have.
What is the Mounjaro KwikPen?
The KwikPen is the pre-filled pen that holds your medicine. The Mounjaro injection goes under the skin once a week, and each pen lasts for four doses. The leaflet has the step by step instructions for use. Doses and strengths are explained in the Mounjaro dosage guide.
Who can take Mounjaro in the UK?
The UK licence sets the group the medicine can be given to. Your prescriber then decides whether it suits you.
| Use | Who it is licensed for | Used together with |
|---|---|---|
| Type 2 diabetes | Adults, adolescents and children aged 10 years and over whose type 2 diabetes is not controlled well enough | Diet and exercise. Alone if metformin is not suitable, or alongside other diabetes medicines |
| Weight management | Adults with a BMI of 30 or above, or a BMI of 27 up to 30 with at least one weight related condition | A reduced calorie diet and more physical activity |
What is Mounjaro for adults with type 2 diabetes?
For adults with type 2 diabetes, Mounjaro is a once weekly injection that helps bring blood sugar down when diet, exercise and other treatment are not enough. It is prescribed by the team looking after your diabetes.
Mounjaro on the NHS
How to get Mounjaro on the NHS depends on national guidance and local rules, and access is narrower than the licence. Meeting the BMI figures starts an assessment. It does not guarantee a prescription. Ask your GP or diabetes team what applies where you live.
Who cannot take Mounjaro?
The summary of product characteristics gives one clear reason not to use it: an allergy to tirzepatide or to any other ingredient. Other situations need a prescriber’s view first, and some mean it should not be used.
Allergy. Do not use Mounjaro if you have had an allergic reaction to tirzepatide or any ingredient in the pen.
Pregnancy and contraception. It should not be used in pregnancy, and is not recommended if you could become pregnant and are not using contraception. It should be stopped at least 1 month before a planned pregnancy. The leaflet also has advice for people on the pill, covered in the Mounjaro side effects guide.
Pancreatitis. The summary says to stop if pancreatitis is suspected, and not to restart if it is confirmed. Tell your prescriber if you have ever had it.
Diabetes with eye disease, insulin or a sulphonylurea. A quick improvement in blood sugar can temporarily worsen diabetic eye disease, and low blood sugar is more likely with insulin or a sulphonylurea. Say so before starting.
Dehydration, kidneys and surgery. Sickness and diarrhoea can dry you out and strain the kidneys. Tell an anaesthetist you take Mounjaro before an operation, as stomach emptying is slower.
Under 18 and weight loss. The weight management licence is for adults. The type 2 diabetes licence starts at age 10.
What do the Mounjaro clinical trials show?
The UK licence rests on two trial programmes. The SURPASS trials studied people with type 2 diabetes, and the SURMOUNT trials studied adults with obesity or overweight. Both compared tirzepatide with a dummy treatment or another medicine, alongside diet and activity advice.
Mounjaro benefits: what the trials looked at
In type 2 diabetes, the trials measured blood sugar. In weight management, they measured body weight. Results are averages from people who were closely monitored, so they describe a group, not a promise for one person. Some people lose more, some less, and some stop treatment because of side effects.
How do you get Mounjaro in the UK?
Mounjaro is a prescription only medicine, so it follows the same path whichever route you use.
- A prescriber, such as your GP, a diabetes team or a registered online prescriber, checks your health, weight and other medicines.
- If it is suitable, the prescriber issues a prescription and sets the dose.
- A registered pharmacy dispenses the pen.
- The prescriber reviews how you are getting on and decides whether to carry on.
Can I get Mounjaro without a prescription?
No. Anyone offering Mounjaro with no prescription, or from a beauty salon or social media seller, is outside the law and the pens may be fake. Check a pharmacy on the GPhC register before you buy. The dose you start on is set by your prescriber, and the Mounjaro dosage guide explains how it changes over time.
What is Mounjaro and is it safe?
The MHRA licenses Mounjaro because the benefits outweigh the risks for the people it is licensed for. That does not mean it is free of side effects. Most are stomach related, such as sickness and diarrhoea. A few are rarer and more serious, including pancreatitis, gallbladder problems, dehydration and allergic reaction. The side effects guide explains which is which, and when to get help.