Wegovy vs Mounjaro: A Factual Comparison for People Already Prescribed

Both medicines are prescription-only injectables taken once a week. Beyond that shared profile, there are meaningful scientific distinctions worth understanding.

Active substance and mechanism

Wegovy contains semaglutide, a GLP-1 receptor agonist. It mimics a gut hormone involved in appetite regulation, promoting a sense of fullness and reducing overall food intake. Mounjaro contains tirzepatide, a dual GIP and GLP-1 receptor agonist — meaning it acts on two appetite-related pathways rather than one. According to the electronic Medicines Compendium, tirzepatide's dual action is pharmacologically distinct from semaglutide's single-pathway approach, though both ultimately reduce appetite and slow gastric emptying to varying degrees.

Dose strengths

Wegovy is available in strengths of 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, and 2.4 mg. Mounjaro is available in strengths of 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. The numbering looks very different because the two active substances are measured on different scales — the figures are not directly comparable. In both cases, titration is managed by your prescriber.

Delivery device

Both are supplied as pre-filled, single-use injection pens. Wegovy pens contain semaglutide in solution; Mounjaro is supplied as the KwikPen device. Your prescriber or pharmacist will show you how to use whichever pen you have been prescribed — and both the Wegovy overview and the Mounjaro guide on this site cover device-specific information in more detail.

Monitoring status

Both medicines carry the black triangle symbol (▼) in many countries, indicating they are subject to additional monitoring. Any side effects you experience should be reported to your healthcare professional and, where applicable, to your national reporting scheme (such as the UK's Yellow Card scheme).

What they share

• Both are prescription-only — neither can be obtained without a prescriber
• Both are once-weekly subcutaneous injections
• Both are typically started at a low dose and adjusted over time by the prescriber
• Both commonly report gastrointestinal side effects such as nausea, vomiting, and constipation, particularly early in treatment
• Neither is insulin, and neither is a substitute for clinical supervision, diet, and activity

For a deeper look at how each medicine is positioned individually, see our Mounjaro comparison overview and the dedicated Mounjaro comparison site guide.

GLP Trackr is built to support people already prescribed either Wegovy or Mounjaro — the app works for both, and you choose your medicine when you set up your profile.

Because both medicines involve a weekly injection schedule with dose titration over time, dose and injection logging is the feature most directly relevant to this comparison. Every injection can be recorded with the date, dose strength, and injection site (abdomen, thigh, or upper arm). The app tracks your site rotation history and suggests your next site automatically, which matters whether you are on pen 1 or pen 12. If you ever need to bring a clear summary of your injection history to a prescriber appointment, the doctor report feature compiles it for you.

Side-effect patterns can also differ between medicines and between individuals, which is why the side-effect tracker lets you log symptoms over time and spot correlations — useful context for any conversation with your prescriber about how your current medicine is working for you.

Always follow the guidance of your prescriber or doctor regarding your medication — any question about whether your current prescription is right for you, or whether a change might be appropriate, is a clinical decision that they are best placed to make.

Ready to keep your journey organised in one place? Download GLP Trackr on the App Store or Google Play and start a free 7-day trial — it works whether you are on Wegovy, Mounjaro, or making the switch between them.