Where Is the Best Place to Inject Mounjaro?

Mounjaro (tirzepatide) is a once-weekly subcutaneous injection, meaning it is delivered into the fatty tissue just beneath the skin. The three commonly used sites are:

• Abdomen — the area around the belly, avoiding a few centimetres around the navel. Many people find this site accessible and easy to use consistently.
• Front of the thigh — the outer portion of the upper thigh. A practical option, particularly when injecting without assistance.
• Upper outer arm — the fleshy area on the back of the upper arm. Some people find this site requires a little more care to reach on their own.

There is no single "most effective" site in terms of how the medicine works — absorption differences between recommended sites are generally considered minor in practice. What matters most is rotating consistently. Injecting repeatedly into the same spot can lead to localised skin changes (sometimes called lipohypertrophy), which can affect how the medicine is absorbed over time.

A good rotation habit means moving to a different area of the same site each week, or cycling through the different sites in a pattern you can remember. Your prescriber or doctor can advise on a rotation approach that suits your routine — and the patient information leaflet that comes with your pen is the definitive reference for technique guidance specific to your device.

For more on site-specific detail for Mounjaro, see our guide on choosing your Mounjaro injection site. If you are on Wegovy (semaglutide), the same general sites apply — you can read more about the best place to inject Wegovy in a dedicated guide.

For a broader look at how these medicines are administered, our weight-loss injections overview covers the wider picture.

Keeping track of which site you used last — and where within that site — is easy to forget over a weekly schedule, especially as months go by. GLP Trackr's injection-site tracking feature is built for exactly this: log each injection with the site you used, and the app tracks your rotation history so you always know where to go next.

Alongside site tracking, the app's dose logging lets you record the strength and date of every shot in one place, and dose reminders mean a weekly injection is less likely to slip your mind. Together, these features turn an easy-to-forget routine into something you can stay consistent with without relying on memory alone.

If you ever notice anything unusual at an injection site — redness, swelling, or discomfort that persists — log it in the app's side-effect tracker and bring it up with your prescriber or doctor at your next appointment. Any concerns about injection sites or technique should always be discussed with your healthcare professional; they know your full history and can give guidance specific to you.

Ready to take the guesswork out of rotation? GLP Trackr is free to try for 7 days — download it on the App Store or Google Play and let the app keep track of your sites for you.