What Is the New Slimming Injection — and How Do You Track It?

Mounjaro and Wegovy are the two most widely discussed prescription weight-management injections currently available. Wegovy contains the active substance semaglutide, a GLP-1 receptor agonist. Mounjaro contains tirzepatide, which acts on both GIP and GLP-1 receptors — making it a dual-action medicine in that sense. Both are supplied as pre-filled, once-weekly injection pens.

These medicines act on appetite-regulating pathways in the brain and gut. Many people report a reduced sense of hunger, a greater feeling of fullness after eating, and a quietening of persistent food thoughts — sometimes called "food noise". Stomach emptying may also slow, which can contribute to that sense of fullness. Individual experiences vary, and these effects are commonly reported rather than guaranteed for everyone.

Because they are prescription-only medicines, suitability is always decided by a prescriber based on your personal health history. Neither medicine is suitable for everyone, and any decision about starting, continuing, or adjusting them belongs with your healthcare professional.

For a broader overview of how injectable weight-management medicines work, see our guide to weight-loss injections. You may also find it useful to read about slimming injections generally, or explore the specific topic of slimming injections available through national health services — noting that access routes vary considerably depending on where you live and your individual clinical circumstances.

According to NHS guidance, both tirzepatide and semaglutide are prescription medicines and should only be used under appropriate medical supervision.

Once you are prescribed one of these injections, staying on top of your weekly routine becomes important — and that is where a dedicated tracking tool makes a real difference. The feature most relevant to injectable medicine is injection-site tracking and rotation: GLP Trackr logs each site you use (abdomen, thigh, or upper arm) and automatically suggests your next rotation, so you never have to remember which area you used last week.

Alongside site rotation, the app logs every dose — date, time, and strength — giving you a clear record of your treatment history. If you ever miss a dose and need to discuss what happened with your prescriber, that log is ready to share. The app's dose reminder feature also sends a gentle nudge on your chosen injection day, so a weekly pen is less likely to slip your mind in a busy week.

If you are curious about what the injection is likely to cost before committing, our page on how much the slimming injection costs gives a neutral overview of that topic — though any specifics are best confirmed with a registered pharmacy and your prescriber.

Any questions about how to administer the injection, what to do if you experience an unusual reaction, or whether the medicine is right for you should be directed to your prescriber or doctor — they know your full medical history and are best placed to advise. If you experience anything severe or persistent, contact a healthcare professional promptly rather than waiting for your next scheduled appointment.

Ready to bring some structure to your weekly injection routine? GLP Trackr is available free on the App Store and Google Play — log your first injection, set up your rotation reminders, and explore a 7-day free trial to see how it fits your journey.