With new prescription weight loss injections now available in the UK, many people are asking: What’s the difference between Mounjaro and Wegovy?

Both medicines have shown powerful results in clinical trials, but they’re not identical. Here we’ll break down the similarities, differences, availability in the UK, and costs, so you can decide which might be right for you.

What Is Wegovy UK?

Wegovy® (semaglutide) is the first weekly injection licensed in the UK specifically for weight management.

• How it works: Wegovy mimics a natural gut hormone (GLP-1) that helps reduce appetite, slow digestion, and regulate blood sugar.

• UK launch: Wegovy was launched in September 2023.

• Who it’s for: Adults with a BMI ≥30, or ≥27 with weight-related conditions such as high blood pressure, prediabetes, or sleep apnoea.

• Effectiveness: NHS and clinical trial data show Wegovy users lose around 15% of their body weight on average, when combined with lifestyle changes.

What Is Mounjaro UK?

Mounjaro® (tirzepatide) is a newer weekly injection designed for type 2 diabetes, but it’s also showing impressive results for weight loss.

• How it works: Mounjaro activates two gut hormones — GLP-1 and GIP, offering a dual effect on appetite and blood sugar control.

• Effectiveness: Clinical studies suggest weight reductions of 20–22% of body weight, which is higher on average than Wegovy.

Side Effects: Mounjaro and Wegovy

Both medicines may cause similar side effects, most commonly:

• Nausea

• Vomiting

• Diarrhoea or constipation

• Indigestion

• Headache

Most side effects improve after the first few weeks. Serious side effects are rare but should always be discussed with a doctor/healthcare professional.

Final Thoughts

Both treatments can be powerful tools when combined with healthy lifestyle changes. Book your initial consultation at Willow Tree Aesthetics today to discuss you options.