Mounjaro is a new weight loss injection that can be prescribed if you meet certain BMI requirements. It is also used for people with type 2 diabetes who have high blood sugar (glucose) levels and contains the active ingredient tirzepatide.

Mounjaro for weight loss comes as an injection pen that can be administered once a week to reduce food cravings, and promote feelings of fullness.

It should always be taken alongside a diet and exercise plan, no matter if you are taking it for weight loss or diabetes.

You can only get Mounjaro on prescription. Mounjaro was only recently approved for weight loss in the UK (8 November 2023) and is available on a private prescription.

Mounjaro contains the active ingredient tirzepatide. It is the first medication that imitates 2 different hormones that can reduce food cravings, appetite, and blood sugar.

These hormones are:
- glucagon-like peptide-1 (GLP-1)
- glucose-dependent insulinotropic polypeptide (GIP)

Mounjaro increases the time it takes to empty your stomach, which makes it easier to feel fuller for longer, helping with weight loss. It also works on the parts of your brain that control appetite and hunger, making you feel fuller even while eating less.

Both GIP and GLP-1 also increase the production of insulin in your body. Insulin is essential for reducing and maintaining blood sugar levels. When injected, Mounjaro can help people with type 2 diabetes to control and manage high blood sugar levels. This is also helpful if you’re using Mounjaro for weight loss, as it can reduce blood sugar spikes. Unregulated blood sugar can also cause food cravings.

The effects on both blood sugar and appetite make it an effective weight loss drug, as it can reduce your calorie intake without craving food in between meals.

Mounjaro should start working immediately, but it may take several weeks to see the full effect of this medicine. This is because your Mounjaro dosage will be increased gradually to reduce side effects.

For weight loss, studies have found that in some cases people who used the largest dose of Mounjaro, 15mg, lost as much as 22.5% of their body weight. You’ll get the best effect from this medication when taking it alongside healthy lifestyle changes, such as eating a balanced diet, reducing snacking between meals, and exercising for 150 minutes a week.

To take Mounjaro for weight loss you should inject your dose once a week, on the same day and at the same time. This helps keep the levels of tirzepatide steady in your bloodstream, reducing the risk of side effects and increasing its effectiveness.

- We only stock Mounjaro as a multi-dose pen. This means that each Mounjaro pen contains 4 doses of the same strength. Make sure to follow your doctor's instructions and the patient information leaflet included with your pen.

- You should only inject Mounjaro (tirzepatide) into the skin of your belly or upper thighs, avoiding any veins or muscles. You can inject in the outer section of your upper arms if they have a substantial subcutaneous layer and you can get someone else to help you do so.

- You’ll need to use a new needle for each injection. Make sure you have a sharps bin nearby so you can safely dispose of it when you’re finished.

- Always check your pen and needle for signs of damage and do not use it if it’s unsealed or bent. You should also check the liquid for discolouration or cloudiness – in case it’s not clear and colourless to slightly yellowish, you may need to use a new pen.

- Before taking your dose, make sure that you’ve got the right medication and right dose according to the Mounjaro dosing schedule. This is especially important if you take other injectable medications like insulin.

Where should I inject Mounjaro?
Mounjaro should ideally be injected into your upper legs, or your stomach. If you choose to inject in your stomach, leave at least a 5cm gap from the belly button. As Mounjaro is only injected once a week, you aren’t likely to get too much soreness and irritation at the injection site. But to avoid this happening, choose a different site each week, even if this is just a different section of the skin in the same area.

Should I take Mounjaro with food?
You can take Mounjaro with or without food, as it’s not being taken by mouth. Find a routine that works for you.

When is the best time to take Mounjaro?
It doesn’t matter what time you take Mounjaro, it will still work until your next dose. It’s important that you take it at the same time and day each week. Choose a routine that works for you and use your calendar or an alarm to remind you when your next dose is due. You can also change your day and time of injection occasionally, but this shouldn’t happen too often.

Is Mounjaro used long term?
Mounjaro is safe as a long term treatment for both weight loss and type 2 diabetes. If you’re taking Mounjaro for weight loss, you’d usually take it until you’ve reached your weight loss goals. Your doctor may stop Mounjaro if your side effects are too strong or you aren’t losing weight as expected.

Mounjaro comes with a dosing schedule so that you can slowly increase your dose. This helps to reduce common side effects like nausea (feeling sick) and vomiting (being sick). No matter what dose you’re currently taking, you’ll only ever take 1 dose a week.

Mounjaro starts at a dose of 2.5mg per week for 4 weeks. You’ll then increase your dose to 5mg once a week for another 4 weeks. After this, your dose can be increased every 4 weeks until the maximum dose of 15mg. Your doctor will let you know when you can increase your dose. This will be determined by any side effects and how well the dose is working for you.

The following doses of Mounjaro pens are available:

2.5mg
5mg
7.5mg
10mg
12.5mg
15mg

This is how much tirzepatide is contained in each injection.

What is the starting dose of Mounjaro?
The starting dose of Mounjaro is always 2.5mg for 4 weeks. Even if you’re switching from another weight loss injection or have taken Mounjaro in the past, you’ll still start on this dose.

What is the recommended dose?
The most weight loss is seen once you reach the maximum dose of 15mg but this will depend on how your body responds to the medication and if you get any side effects.

Important: Never increase the dose higher than recommended by your doctor – this will increase the risk of strong side effects, severe illness, and might cause you to stop or pause your treatment, which will hinder your weight loss.

What if I miss a dose?
If you miss a dose of Mounjaro, what you do next will depend on how long it’s been since your last dose was due.

If it’s been 4 days or less since your last dose was due, take it as soon as you remember. You can then continue treatment as normal on your usual day and time, even if this means taking 2 doses a few days apart.
If it’s been longer than 4 days, skip the missed dose then continue treatment when your next dose is due.

Which factors can affect my dosage?
The factors that can affect your Mounjaro dosage may include:
- how long you’ve been taking the medication for
- whether you’ve gotten side effects
- your weight loss results on your current dosage
- how many doses have been missed, as you may need to stay on a lower dose for longer if you’ve missed doses

You’ll usually follow the Mounjaro dosing schedule, which means starting at a lower dose before increasing every 4 weeks.

Mounjaro delivered up to 22.5% weight loss in adults with obesity or overweight in SURMOUNT-1