Injectable Weight Loss: Sites, Rotation, and Staying on Track

Both Mounjaro and Wegovy are prescribed as once-weekly subcutaneous injections. The three most commonly used injection sites are the abdomen (avoiding the area immediately around the navel), the outer thigh, and the upper arm. Rotating between these sites — rather than returning to the same spot week after week — helps reduce the risk of localised skin reactions such as redness, bruising, or changes in tissue texture at the injection area.

Why rotation matters

Repeated injections in one small area can cause the skin and underlying tissue to become less responsive over time. A simple rotation pattern — for example, cycling through abdomen, thigh, and arm in sequence — spreads the load across different tissue sites. Your prescriber or doctor can advise on a rotation approach that suits you, and the patient information leaflet that comes with your pen will include guidance specific to your medicine.

What the pens look like in practice

Both medicines come as pre-filled, disposable injection pens. Each pen contains a single dose, used once weekly on a consistent day. The exact handling steps — attaching a needle, priming, and administering — are set out in the instructions for use in your pack. If anything about the pen or the injection process is unclear, your prescriber or pharmacist is the right person to ask; this page describes what the app logs, not clinical injection technique.

For a broader overview of how these medicines work, see our guide on GLP-1 injectable medicines, or explore what the evidence says about injectable weight loss options. You may also find it useful to read about non-injectable weight loss medicines for context on the wider landscape — though the choice between any of these is always one to make with your prescriber.

If you want to understand how a specific manufacturer approaches this treatment area, our overview of healthcare companies involved in injectable weight loss gives useful background.

Keeping track of which injection site you used last — week after week, for months — is easier said than done. That is where GLP Trackr's injection-site tracking and rotation feature earns its place: you log each site after your injection, and the app keeps your full rotation history so you always know where to go next. There is no need to rely on memory or sticky notes.

Alongside site tracking, the app lets you log each dose with its date, time, and strength — building a clear, timestamped record of your treatment history. Pair that with dose reminders and missing a weekly injection becomes far less likely, even during busy or disrupted weeks.

All of this can be brought together in the app's doctor report feature, giving you a clean summary to share at your next prescriber appointment — useful for discussing how your injection routine is going, any site reactions you have noticed, or questions about your schedule.

Return to our main guide on weight loss injections for a fuller picture of everything covered in this content family.

Any questions about your injection technique, site reactions, or schedule should be directed to your prescriber or doctor — they know your full history and are best placed to advise. If you notice a site reaction that is severe, spreading, or not settling, contact your healthcare professional promptly.

Ready to take the guesswork out of injection-site rotation? GLP Trackr is free to try for 7 days — download it on the App Store or Google Play and let it handle the tracking while you focus on the journey.