Mounjaro as a Diet Injection: What to Know About Sites and Rotation

Mounjaro is supplied as a pre-filled pen and is administered as a subcutaneous injection — meaning it goes into the fatty tissue just beneath the skin. According to the electronic Medicines Compendium (eMC), the three recommended areas are the abdomen (stomach), the front of the thigh, and the upper arm. Each has slightly different tissue depth and absorption characteristics, but all are suitable sites as directed by your prescriber or doctor.

Why rotate?

Using exactly the same spot week after week can lead to localised skin changes — including lumps, hardened tissue, or irritation — which may affect how the medicine is absorbed. Rotating sites, and moving to a slightly different spot within each area each time, helps keep the skin in good condition throughout your treatment.

What to be aware of at each site

• Abdomen: Avoid the area directly around the navel. Many people find this the most accessible site for self-injection.
• Thigh: Use the front and outer part; avoid the inner thigh.
• Upper arm: This site is often easier with assistance; if self-injecting, the abdomen or thigh may be more practical.

For full guidance on injection technique — including how to prepare the pen, where precisely to place it, and what to do if you notice a site reaction — always follow the patient information leaflet (PIL) that came with your medication and the advice of your prescriber or doctor. Your prescriber is best placed to guide you on technique for your individual circumstances.

If you want to understand more about the broader context of weight-loss injections like Mounjaro, the guide to weight-loss injections covers the wider picture. You may also find it helpful to read about Mounjaro injections generally or get a practical walkthrough on how to do your Mounjaro injection.

Keeping a mental note of which site you used last week is easy to forget — especially over many months of weekly injections. GLP Trackr's injection-site tracking feature lets you log the exact site and location after each dose, and the app uses that history to suggest your next rotation automatically, so you never have to guess.

Beyond site tracking, the app also logs each dose with its date, time, and strength — giving you a clear record of your full injection history in one place. If you ever notice a site reaction or discomfort, you can log it in the side-effect tracker and bring that pattern to your next prescriber appointment rather than trying to recall it from memory.

For more on making the most of your weekly dose, see the page on weight-loss injection tracking for Mounjaro. And if you want a broader view of managing your journey, the weight-loss injections hub is a good place to explore.

If you experience any injection-site reactions that are severe, persistent, or concern you — or if you have any questions about your technique or schedule — contact your prescriber or doctor. GLP Trackr helps you record what you notice so those conversations are better informed; it is not a substitute for their guidance.

Ready to take the guesswork out of rotation? Download GLP Trackr on the App Store or Google Play and start your free 7-day trial — your injection history will be organised from your very first log.