Mounjaro injection sites: where's best to inject?

Simon Edward • 26 November 2024

What's the best Mounjaro injection site? Should you change it with each dose? Find out in our quick guide.

A man in a striped shirt and tie is injecting himself with an insulin pen.

Mounjaro is an injectable weight loss medication that comes in a pre-filled KwikPen. This is a pen-shaped device that's designed to make it easy to inject the drug yourself at home.


Most patients get used to injecting themselves quite quickly. However, if you've never done it before, you might feel a little nervous – and you probably have lots of questions.


In this article, we tackle one of the most common: 'Where am I supposed to inject Mounjaro?'


Ready? You might feel a tiny pinch…


What are the possible Mounjaro injection sites?


You can choose any one of these injection sites for Mounjaro:


The soft part of your belly (at least 5cm from your belly button)

The front side of either thigh

The back of either upper arm (if someone else is giving the injection)


These injection sites all have something in common: they contain subcutaneous tissue. This is a fatty layer underneath the skin.


Mounjaro is taken as a subcutaneous injection. In other words, it's injected under the skin into this fatty layer. It doesn't need to be injected directly into a vein.


The good news is that subcutaneous injections are very easy to take. Most people find them relatively painless, too. Bear in mind that we all experience pain differently, though – and some injection sites tend to hurt more than others.


Another reason that Mounjaro is taken as a subcutaneous injection is that it helps the drug work more effectively. Injecting Mounarjo into a fatty layer ensures it's absorbed into the body at the right pace.

A woman is getting an injection in her arm.

What's the best injection site for Mounjaro?


If you're injecting yourself, it's best to do it in your belly or thigh, as these areas are easiest to access. If someone else is giving you the injection, they should do it in the back of your upper arm.


These guidelines aside, it's more or less up to personal preference. Unless your doctor advises

otherwise, you're free to choose between injecting yourself in the belly and injecting yourself in the thigh.


It's worth trying both. You might find that one injection site hurts less than the other – or is simply easier or more comfortable for you.


Should you change the Mounjaro injection site each time you take the medication?


Yes. We recommend that you change the injection site with each weekly dose.


This doesn't mean you have to choose a different part of your body. You can, for instance, always take the injection in your belly. However, if choose to do this, you should inject it into a different part of your belly each week.


Rotating Mounjaro injection sites like this is important because it minimises the risk of developing infections and other problems.


We hope this guide helps you get to grips with your Mounjaro treatment. Want to learn more about Mounjaro? Discover SemaPen's expert-led Mounjaro medication programme or read our frequently asked questions.

Mazdutide is a GLP-1 injection that works similarly to Mounjaro. Discover everything you need
by Simon Edward 1 December 2025
Mazdutide is a GLP-1 injection that works similarly to Mounjaro. Discover everything you need to know about this up-and-coming weight loss drug.
Want to know if you're eligible to take Mounjaro? Discover the threshold BMI for Mounjaro
by Simon Edward 29 November 2025
Want to know if you're eligible to take Mounjaro? Discover the threshold BMI for Mounjaro in private and NHS settings.
Is buying the cheapest Mounjaro really worth it? Learn the risks of 'bargain' options and why safe s
by Simon Edward 29 November 2025
Is buying the cheapest Mounjaro really worth it? Learn the risks of 'bargain' options and why safe support matters.
Have you heard about semaglutide tablets?
by Simon Edward 24 November 2025
Have you heard about semaglutide tablets? Let's compare Wegovy injections and oral semaglutide in terms of weight loss.
Seeing weight loss compared to objects can help you understand and celebrate your progress.
by Simon Edward 21 November 2025
Seeing weight loss compared to objects can help you understand and celebrate your progress. Visualise success with these simple comparisons.
Can Wegovy make you sleepy? Learn everything you need to know about Wegovy and tiredness
by Simon Edward 17 November 2025
Can Wegovy make you sleepy? Learn everything you need to know about Wegovy and tiredness in our guide.
We can't fix obesity without fixing the stigma associated with the disease.
by Simon Edward 14 November 2025
We can't fix obesity without fixing the stigma associated with the disease. Discover what needs to change in our culture and healthcare.
As one of the UK's biggest health challenges, obesity comes at a great cost to the NHS and others.
by Simon Edward 10 November 2025
As one of the UK's biggest health challenges, obesity comes at a great cost to the NHS and others. Learn the true cost of obesity in the UK.
It's not safe to use Mounjaro while pregnant. Learn about the risks associated with Mounjaro
by Simon Edward 7 November 2025
It's not safe to use Mounjaro while pregnant. Learn about the risks associated with Mounjaro and pregnancy.
We all know eating fruit is good for us, but what is a good fruit for weight loss? Find out how
by Simon Edward 3 November 2025
We all know eating fruit is good for us, but what is a good fruit for weight loss? Find out how fruit fits into a healthy, balanced diet.
More posts