Mounjaro is a prescription-only treatment for weight loss and type 2 diabetes. It comes as a weekly self-injectable pen and contains the active ingredient tirzepatide. It works by suppressing appetite, making you feel less hungry.

Mounjaro mimics hormones that naturally occur in the gut after eating, called incretins. Incretins have many functions, such as:

• slowing down the emptying of the stomach
• sending signals to your brain that you’re full after eating
• increasing insulin levels

These combined effects help people feel full after a meal by signalling to the parts of the brain responsible for appetite, making it easier to eat less.

To be eligible for Mounjaro, you must have:

• a BMI (body mass index) of 30 kg/m² or over (obese)
• a BMI between 27 and 30 kg/m² (overweight), and a weight-related health condition such as high cholesterol, high blood pressure, pre-diabetes or heart problems

You’ll also need to have no health problems or take any medications that may interact with taking Mounjaro,

Find out if you are eligible through our online assessment.

The active ingredient tirzepatide works by activating the receptors of 2 natural incretin hormones: GIP and GLP-1. Both of these hormones affect your appetite by slowing down the emptying of the stomach after a meal. They also send signals to your brain to reduce your appetite after eating. This action creates a feeling of being full and so makes you feel less hungry, even when you have eaten less, which can aid in weight loss.

For diabetic patients, Mounjaro increases the production of insulin, which is released into your body to lower blood sugar levels.

Mounjaro is an effective treatment for both weight loss and regulating blood sugar levels. A recent clinical trial has shown that people who used Mounjaro lost up to 22.5% of their body weight on the highest maintenance dose (15mg tirzepatide, once per week) within 72 weeks.

Here is a detailed breakdown of the average weight change for each maintenance dosage in comparison to participants who took the placebo from the same clinical trial:

Average weight loss on different Mounjaro doses

These results show that people taking Mounjaro for weight loss can lose more weight than those taking a placebo, i.e. without the help of weight loss medication.

To inject Mounjaro safely, always carefully read the package leaflet and follow the instructions of your doctor.

Worried about self-injection?

"Self-injecting medication may be an uncomfortable idea for many people. But, Mounjaro injections are not the same as ones that might be used for things like vaccinations. Mounjaro comes in an easy-to-use injection pen, which isn’t the same as using a standard injection needle. Mounjaro uses a much smaller needle than the one for vaccinations and the liquid isn’t pushed by hand." – Dr Babak Ashrafi.

When you request any self-injection medication from Asda, our doctors can provide you with advice on how to use it, and if you need extra help, you can also message them for free through your account.

Please note: Mounjaro is solely to be used alongside a healthy diet and regular exercise.

Where should I inject Mounjaro?

Mounjaro can be injected either in the abdomen or thigh. Select an injection site that you feel most comfortable with. Switch injection sites weekly and divide the chosen area into four sections which will be your injection sites. Inject at least one finger width away from the last injection. If injecting in the abdomen, inject at least 5cm away from the navel.

How to inject Mounjaro step by step

• Wash your hands using water and soap.
• Prepare the pen and check that it’s not expired or damaged and the liquid looks as it should.
• Attach a new needle to the pen.
• Slowly turn the dose knob until you hear 2 clicks.
• Prime the pen to release air bubbles and make sure it’s working correctly.
• Adjust the dosage to ‘1’.
• Insert the needle, push down the dose knob and count slowly to 5.
• Pull the needle out of your skin and check if the dose count is back at ‘0’.
• Remove the needle and replace the pen cap.

Make sure you take your injection at the same time each week (when exactly is up to you) to get the best effect and try not to forget any doses. 

How long you can stay on Mounjaro depends on how much weight you need to lose to achieve a healthy BMI and if you need help to maintain that weight. If you are not able to lose weight on Mounjaro, a doctor can recommend alternatives for you.

Mounjaro should be taken once a week. It can be taken at any time of the day, with or without food. You should select a day and time that is convenient or easy for you to remember. You may find it useful to set a reminder on your phone to ensure you do not miss a dose.

If you want to change the day of the week you use Mounjaro, you’ll need to leave at least 72 hours (3 days) between doses, and then you should carry on taking it weekly. It’s important that you don’t do this often, or it could decrease the effectiveness of your treatment.

Missed doses should be taken within 96 hours (4 days) of the missed dose. If it is outside of 96 hours, miss the dose and continue to your next scheduled dose. Speak to your doctor if you miss several doses, as you may need to start the dosage schedule again.

When you stop taking Mounjaro for weight loss, you may regain the weight you have lost if you don’t stick to your weight loss plan. When you stop the medication, you will get your appetite back, so you won’t feel full for as long after a meal. This means you might be tempted to eat more than you did when taking Mounjaro, possibly causing you to gain weight.

Sticking to your original weight loss plan, such as diet improvements and increased exercise, can help with weight control. So if you do stop taking Mounjaro, you should continue with these lifestyle changes and make reasonable adjustments to avoid putting weight back on. If you had any side effects from Mounjaro, these should go away within a few weeks of when you stop taking it.

Mounjaro is available in 6 dosages, which you move up over time.

The dosages of Mounjaro available are:

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

You will start your journey with Mounjaro on the lowest dose of 2.5 mg, which needs to be injected once a week for 4 weeks. If the medication works well for you, you can increase your dose to 5mg for 4 weeks. Depending on progress, you can either stay on this dose or you can increase the dose in 4-week blocks by 2.5mg each time. The maximum dosage available for Mounjaro is 15mg. We have more information on each dose and how to follow the dosage schedule safely in our Mounjaro dosage guide.

Don’t increase your dosage earlier than 4 weeks and speak to your doctor if you get side effects on your current dose. Never take more than the maximum dosage of 15mg, as this can lead to severe side effects.

You don’t have to go up to the maximum dosage if you don’t want to. As long as your treatment is working, you can stay at whatever dose works best for you. Higher doses can be more effective but also come with a higher risk of side effects and can cost more.

What are the side effects of Mounjaro?

You might experience side effects when you start taking the medication and when you increase your dose. For many people, these side effects are reduced over time and should not be severe.

Very common side effects

• feeling sick (nausea)
• diarrhoea
• vomiting
• constipation
• low blood sugar (if used with certain diabetes medications)

Common side effects

• indigestion
• stomach pain
• dizziness
• allergic reactions
• low blood pressure
• hair loss
• feeling tired
• bloating
• burping
• gas
• reflux or heartburn
• injection site reactions
• an increased level of some pancreatic enzymes as shown in blood tests (such as lipase)

Uncommon side effects

• gallstones
• fast pulse
• injection site pain
• gall bladder infection
• inflammation of the pancreas
• an increased level of some pancreatic enzymes as shown in blood tests (such as amylase)
• increased calcitonin levels in blood

For a full list of the side effects see the Patient Information Leaflet.

Mounjaro is not suitable for anyone who is:

• under the age of 18
• pregnant or breastfeeding
• allergic to any of the ingredients in Mounjaro

You may not be able to use Mounjaro if you have:

• kidney problems
• ever had pancreatitis
• a problem digesting food
• an issue with your eyes such as diabetic retinopathy

Although there are no known foods that interact with Mounjaro, there are certain foods you should avoid if you want to achieve maximum results. For example, it is best to avoid:

High glycaemic fruit and vegetables as these can cause a spike in your blood sugar levels. They include:

• pineapple
• watermelon
• mango
• overripe bananas
• potatoes
• sweetcorn

High-sugar foods such as:

• sweets
• biscuits
• cakes
• fizzy drinks

Fried foods, which often contain unhealthy fats and may increase the risk of nausea while taking Mounjaro. These foods include:

• burgers
• sausages
• fried eggs
• chips
• bacon

Mounjaro warnings and risks 

Mounjaro comes with some safety risks. You will not be able to use Mounjaro if you are allergic to any of the ingredients in Mounjaro.

Mounjaro may also cause serious side effects, including:

• an inflamed pancreas (pancreatitis)
• severe stomach issues, such as gastroparesis
• gallstones
• severe allergic reaction
• severe gastrointestinal issues
• severely low sugar levels (when used in conjunction with diabetic drugs or if taken in overdose)

You should discuss any existing medical problems or side effects with your doctor.

Mounjaro interactions 

Mounjaro treatment can cause hypoglycemia (low blood sugar) if it’s taken together with sulfonylurea or insulin (other diabetes treatments).

You should tell your doctor before using Mounjaro for weight loss if you take any other prescribed or over-the-counter medications or herbal remedies.

There are several Mounjaro alternatives available for weight loss, although they may contain different active ingredients. These include:

• Wegovy – Contains semaglutide (a GLP-1 receptor agonist) which is gradually increased to a maintenance dose of 2.4 mg. People lose up to 15% of their starting body weight on average when taking the maintenance dose.
• Xenical – A branded medication that contains orlistat at a dose of 120 mg per tablet. Works by reducing the amount of fat you absorb when taken with meals containing fat, up to 3 times per day. Some people lose 10% or more of their starting body weight within 6 months with the help of Xenical.
• Orlistat 120mg – A generic version of Xenical which works in the same way. Can also help you to lose 10% or more of your starting body weight than through dieting alone within 6 months of treatment. As it’s unbranded, it usually costs less.
• Mysimba – A diet pill that contains 2 active ingredients: 8 mg of naltrexone hydrochloride and 90 mg of bupropion hydrochloride. It’s taken once or twice a day, up to a maximum dose of 2 tablets, twice a day. Works by affecting the parts of your brain responsible for appetite and can also reduce cravings. After 56 weeks of treatment, people lost on average 8.1% of their starting body weight.
• Alli – A weight loss medication that can be bought over the counter, although a pharmacist will still need to check your medical history first. Also contains orlistat (just like Orlistat 120 mg tablets and Xenical) but at a lower dose of 60 mg per tablet. Works in the same way and can also help you lose up to 10% or more of your starting body weight after 6 months than through dieting alone.
• Nevolat – Contains liraglutide, which is gradually increased to a maintenance dose of 3.0mg. People lose up to 8% of their starting weight in 56 weeks on the maintenance dose.