Mounjaro vs Wegovy: What Are the Differences?

At the most fundamental level, the two medicines work on different receptors in the body. Understanding this distinction is useful context — it does not imply one is better or more suitable than the other for any individual.

Active substance and mechanism

• Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist. It acts on both glucose-dependent insulinotropic polypeptide (GIP) receptors and glucagon-like peptide-1 (GLP-1) receptors simultaneously.
• Wegovy (semaglutide) is a GLP-1 receptor agonist only. It targets the GLP-1 pathway that regulates appetite and feelings of fullness.

Both medicines are commonly described as increasing the sense of fullness, reducing appetite, and — for many people — reducing what is sometimes called "food noise". These effects are reported to vary between individuals.

How they are taken

Both are administered as a subcutaneous injection once a week, using a pre-filled pen device. Both are typically started at a lower dose and adjusted over time under the direction of the prescriber. The available dose strengths differ between the two medicines — your prescriber or doctor, or the patient information leaflet that came with your pen, will confirm the specific doses that apply to you. You can read more about Mounjaro as a medicine or explore an overview of Wegovy for factual background on each.

Commonly reported side effects

Because both act on GLP-1 pathways, the most commonly reported side effects overlap considerably: nausea, vomiting, diarrhoea, constipation, indigestion, and injection-site reactions are noted with both. Tirzepatide's additional GIP activity means its tolerability profile may differ in some respects — but individual experience varies widely, and any concerns about side effects should be discussed with your healthcare professional.

Both medicines carry a black triangle (▼) designation in some markets, meaning they are subject to additional monitoring. If you experience side effects, report them to your healthcare professional and to your national reporting scheme (such as the UK's Yellow Card scheme).

Who they are prescribed for

Suitability for either medicine depends on individual clinical factors assessed by your prescriber. Neither is suitable for everyone. If you are curious about whether you meet typical criteria, your prescriber is the right person to ask — or you can look at typical requirements for Mounjaro prescriptions for general background. Neither medicine is a substitute for clinical supervision, dietary adjustment, and physical activity.

GLP Trackr is built for people already taking Mounjaro or Wegovy — and it works equally for both. Whether you are mid-titration on tirzepatide or several months into your Wegovy journey, the app gives you one place to log everything that matters.

The most useful starting point for anyone on either medicine is dose and injection logging. Every week, you can record which pen you used, the dose strength, the injection site, and the date — so your history is always clear and you never lose track of where you are in your schedule. The app also tracks injection-site rotation and suggests your next site, which is especially helpful given that both medicines are injected weekly at rotating sites.

Beyond injections, you can log how you feel day to day — energy, mood, appetite, and any side effects — and use the insights tools to see patterns over time. That record becomes genuinely useful when you have an appointment with your prescriber, particularly if you want to discuss how you have been tolerating your current dose. The doctor report feature lets you bring a structured summary of your journey to those conversations.

Whatever prompted you to compare these two medicines, the tracking habits you build now will serve you throughout your journey. If cost or access has been on your mind, you might also find it helpful to read about Mounjaro pricing considerations or what to do if your pen arrives warm — practical topics for people already managing their treatment.

Any decision about which medicine you take, or any change to your dose or treatment, should be made with your prescriber — not based on a comparison article. GLP Trackr supports your journey; it does not advise on it.

Ready to bring your weekly tracking together in one place? GLP Trackr is free to try for 7 days — available now on the App Store and Google Play.