Where Do You Inject Mounjaro?

The three sites most commonly used for weekly GLP-1 injections like Mounjaro and Wegovy (semaglutide) are:

• Abdomen — the fatty area of the stomach, typically at least a few centimetres away from the navel
• Thigh — the outer or front portion of the upper thigh; if you are wondering where in the thigh to inject Mounjaro, the outer mid-thigh is the area most commonly referenced in patient information
• Upper arm — the back or outer area of the upper arm, a site also used for Wegovy injections

Each of these areas contains enough subcutaneous (under-skin) fat for the medicine to absorb gradually, which is how it is designed to work. Injecting into muscle rather than fat can affect absorption and may be more uncomfortable, so staying in the subcutaneous layer matters — your prescriber or the patient information leaflet that came with your pen can guide you on how to do this correctly.

Rotation — moving to a different site or a different spot within the same site each week — helps prevent the build-up of hard, lumpy tissue (lipohypertrophy) that can develop if the same small area is used repeatedly. This is a standard principle for anyone using weekly weight-loss injections, whether Mounjaro, Wegovy, or similar medicines.

Mounjaro is a once-weekly injection, not a daily one. If you are unsure about your schedule, the page on how often you inject Mounjaro covers the weekly dosing schedule in more detail. For a broader look at all the approved injection areas, the page on where you can inject Mounjaro goes into further depth, and where to inject Mounjaro addresses common questions about choosing the best location for you.

Always follow the patient information leaflet included with your pen and the guidance of your prescriber or doctor — they know your full medical history and can advise on any adjustments specific to you.

Keeping a mental note of which site you used last week — and exactly where within that site — is surprisingly easy to lose track of, especially across months of weekly injections. GLP Trackr's injection-site tracking feature lets you log each injection as you do it, recording the site (abdomen, thigh, or upper arm) and the side (left or right). The app then tracks your rotation history and can suggest your next site, so you never have to guess or rely on memory.

Alongside site rotation, the app logs the date, time, and dose strength of each injection, giving you a complete record of your Mounjaro or Wegovy journey in one place. Dose reminders mean you are less likely to lose track of your weekly schedule — a particularly useful safety net during busy periods or when travelling.

If you ever want a clear summary of your injection history to bring to an appointment, the doctor report feature compiles your logged data into a format you can share with your prescriber. For the full picture on managing your weight-loss injection journey, the weight-loss injections hub is a good place to start.

If you notice anything at an injection site — redness, persistent swelling, or lumps — that concerns you, contact your healthcare professional promptly rather than waiting for your next scheduled appointment.

Log every injection, track your rotation, and never lose your place in your weekly routine — GLP Trackr is free to try for 7 days on the App Store and Google Play.