How to Use Your Mounjaro or Wegovy Injection — and Track Every Dose

Mounjaro (tirzepatide) and Wegovy (semaglutide) are both administered as subcutaneous injections — meaning just under the skin — once a week. The three commonly used sites are the abdomen (avoiding the area immediately around the navel), the front of the thigh, and the outer upper arm.

Why rotation matters

Injecting repeatedly into the same spot can cause localised skin changes over time, such as hardening or sensitivity at the site. Rotating between different areas — and varying the exact position within each area — helps reduce this risk. Your prescriber or the patient information leaflet that came with your pen will have specific guidance on this.

The Mounjaro KwikPen and Wegovy pen

Each manufacturer's pen works slightly differently in terms of how you prime it, confirm the dose, and complete the injection. Always follow the step-by-step instructions in the leaflet supplied with your specific pen. If you are unsure about any part of the process, ask your prescriber, pharmacist, or a nurse before your next dose. For a closer look at the Mounjaro autoinjector, see our guide on using the Mounjaro KwikPen, and for Wegovy pen users, our step-by-step Wegovy pen overview covers what to expect.

Staying consistent with your weekly schedule

Because these are once-weekly injections, it helps to pick the same day each week. Missing a dose or losing track of which day you last injected is easier than it sounds, especially if your schedule changes. Our broader guide to using Mounjaro weight loss injections covers the weekly routine in more detail, and the weight loss injections hub has further resources across the full journey.

Reporting side effects

If you experience injection-site reactions or other side effects, your prescriber should know. Many countries also have national reporting schemes — for example, the UK's Yellow Card scheme — where suspected side effects can be reported. Check which scheme applies in your country.

Remembering which site you used last week, which area within that site, and exactly when you injected can become genuinely difficult over the months of a treatment course. GLP Trackr is built specifically for this.

Injection-site tracking and automatic rotation

Each time you complete an injection, you can log the site and the specific area you used. GLP Trackr keeps a history of your rotation and can suggest where your next injection should go — so you never have to remember manually. This is especially useful for people who use all three sites and want to be systematic about spreading injections out over time.

Dose logging and reminders

Alongside site tracking, the app lets you log the dose strength and the date and time of each injection. If your weekly injection day approaches and you have not yet logged a dose, a reminder nudges you — because as the brand puts it, never forgetting a dose again is one of the simplest ways to stay consistent. For more on the full Mounjaro injection routine, see our complete guide to using Mounjaro, and if you have questions about a particular dose stage, our page on the Mounjaro golden dose may be useful too.

A record to bring to your prescriber

Having a log of every injection — dates, sites, dose strengths — gives you something concrete to discuss at your next appointment. GLP Trackr can generate a summary of your injection history alongside other tracked data, making those conversations more informed.

Any questions about your injection technique, dose timing, or which site to use should go to your prescriber or doctor — they know your full history and the specifics of your pen. GLP Trackr records your journey; it does not replace that clinical guidance.

Ready to take the guesswork out of injection-site rotation? Download GLP Trackr on the App Store or Google Play and explore it free for your first 7 days.