What Is the Name of the Slimming Injection?

When people refer to a "slimming injection" or "weight-loss jab", they are almost always talking about one of these two medicines:

• Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, supplied as a pre-filled injection pen and taken once weekly.
• Wegovy (semaglutide) — a GLP-1 receptor agonist, also supplied as a pre-filled pen and taken once weekly.

Both medicines act on appetite-regulating pathways in the body. Many people experience an increased sense of fullness and a reduction in what is often described as "food noise" — the constant preoccupation with eating. These are commonly reported effects; individual experience varies.

It is worth knowing the difference between the brand name and the active substance. Mounjaro is the brand name; tirzepatide is the active ingredient. Wegovy is the brand name; semaglutide is the active ingredient. You may see either name on your prescription or packaging.

Both medicines are prescription-only and subject to additional monitoring. Any side effects should be reported to your healthcare professional and to your national reporting scheme (such as the UK's Yellow Card scheme).

For a broader overview of how these medicines are used, visit our guide to weight-loss injections. You may also find it useful to read about the newer slimming injections now available or get more detail on the names of injections used for weight loss.

Once you have been prescribed Mounjaro or Wegovy, keeping track of each injection becomes an important part of staying consistent. GLP Trackr's injection-site tracking and rotation feature lets you log exactly where you injected — abdomen, thigh, or upper arm — and the app keeps a history so it can suggest your next site automatically. Rotating sites is generally recommended, and having a clear record removes the guesswork.

Alongside site tracking, you can log the dose strength and date of each injection, and set a dose reminder so a weekly shot is never accidentally missed. Everything stays in one place, making it straightforward to review your injection history before a prescriber appointment.

If you are curious about the cost side of your prescription, our page on how much the slimming injection costs addresses that topic, though GLP Trackr itself does not sell, supply, or source any medication.

Always follow the guidance your prescriber or doctor has given you about your injection schedule. If anything feels wrong — an unusual reaction at the injection site, or any symptom that concerns you — contact your healthcare professional promptly. GLP Trackr helps you record what you notice so you can have a more informed conversation with them; it is not a substitute for their advice.

Ready to keep every injection logged and your rotation on track? Download GLP Trackr free on the App Store or Google Play — your first 7 days are free to try.