The Difference Between Wegovy and Mounjaro: A Factual Overview

The most fundamental difference between Wegovy and Mounjaro lies in their active substances and how they act in the body.

Wegovy (semaglutide)

Wegovy contains semaglutide, a GLP-1 receptor agonist. GLP-1 (glucagon-like peptide-1) is a hormone involved in regulating appetite and blood sugar. By mimicking GLP-1, semaglutide acts on appetite-regulating pathways, and many people experience a reduced sense of hunger and increased feelings of fullness. It is supplied as a pre-filled pen, with dose strengths including 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, and 2.4 mg. Dosing typically starts low and is adjusted over time by the prescriber.

Mounjaro (tirzepatide)

Mounjaro contains tirzepatide, which is a dual GIP and GLP-1 receptor agonist. In addition to acting on GLP-1 pathways, it also activates GIP (glucose-dependent insulinotropic polypeptide) receptors. This dual action is the key pharmacological distinction from semaglutide. Mounjaro is also supplied as a pre-filled pen, with dose strengths including 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg, again started low and adjusted by the prescriber.

What they have in common

• Both are prescription-only medicines — neither can be obtained without a prescriber
• Both are given as once-weekly subcutaneous injections
• Both act on appetite-regulating pathways; many people commonly report reduced hunger and slower stomach emptying
• Both carry a black triangle (▼) status in the UK, meaning side effects should be reported to your national reporting scheme (such as the UK's Yellow Card scheme) and to your healthcare professional
• Both are used alongside diet and physical activity, under clinical supervision

For a detailed side-by-side look at these two medicines, see our Wegovy vs Mounjaro comparison hub, or explore further in our related guides on what makes Wegovy and Mounjaro different and understanding the difference between these two treatments. You may also find it useful to read a closer look at how Wegovy and Mounjaro compare.

According to the electronic Medicines Compendium (eMC), both medicines have prescribing information that details their approved use, dosing schedules, and full side-effect profiles — your prescriber will have reviewed this when determining which medicine suits you.

GLP Trackr is built for people on both Mounjaro and Wegovy — the app does not favour one over the other, just as this page does not.

Because both medicines follow a weekly injection schedule with gradually adjusted doses, dose and injection logging sits at the heart of what the app does. You can record each injection — the dose strength, the date and time, and the site (abdomen, thigh, or upper arm) — so you always have a clear picture of where you are in your treatment. The app tracks your injection-site history and suggests your next rotation, which is useful regardless of which pen you are using.

Both medicines share a similar side-effect profile (nausea, fatigue, and gastrointestinal symptoms are commonly reported for both), so the app's side-effect and symptom tracker works equally well whether you are on semaglutide or tirzepatide. Logging how you feel over time creates a record you can bring to your prescriber appointments — far more useful than trying to recall weeks of symptoms from memory.

Any decision about which medicine is right for you, or whether to switch, belongs with your prescriber or doctor. GLP Trackr helps you make the most of whichever treatment you have been prescribed.

Ready to bring some structure to your weekly injection routine? GLP Trackr is available free on the App Store and Google Play, with a 7-day free trial to get started.