Mounjaro vs Wegovy: Which is Better for Weight Loss? (2026)
Mounjaro and Wegovy are the two most effective weight loss treatments available in the UK. Both work, but they work differently — and one has significantly better clinical trial results. Here's the definitive comparison.
Mounjaro vs Wegovy for Weight Loss in the UK: A 2026 Comparison
In the ever-growing landscape of weight loss medications, Mounjaro and Wegovy are two drugs making headlines in the UK. Both have shown promise in helping people lose significant amounts of weight, but they work differently and come with different costs and considerations. This article provides a detailed, evidence-based comparison between these two options, based on current knowledge and UK-specific context in 2026. Remember, always consult your GP before starting any medication for weight loss.
How Do They Work?
Mounjaro and Wegovy belong to a class of medications called incretin-based therapies, which influence your body’s hormones to help reduce appetite and increase feelings of fullness. However, there are key differences in how they work:
- Mounjaro: This is a dual agonist of GLP-1 (glucagon-like peptide-1) and GIP (gastric inhibitory polypeptide) receptors. By stimulating both, Mounjaro acts on multiple pathways that regulate appetite, insulin secretion, and energy balance. This dual action can offer stronger effects on appetite suppression and metabolism.
- Wegovy: This drug is a single agonist targeting only the GLP-1 receptor. GLP-1 activates pathways in the brain to reduce hunger and slow stomach emptying, helping users feel fuller for longer.
In simple terms, while both reduce appetite and support weight loss, Mounjaro’s dual action potentially provides a more powerful effect.
Clinical Trial Results
Both medications have been studied extensively in clinical trials:
- Mounjaro: Trials known as the SURMOUNT series demonstrated an average weight loss of around 22.5% of body weight after 72 weeks of treatment. These results were seen in people with obesity or overweight with related health conditions.
- Wegovy: The STEP trials showed an average weight reduction of about 15% over 68 weeks. These trials also included a similar group of participants with overweight or obesity.
While direct comparisons should be cautious due to different trial designs, the numbers suggest Mounjaro may provide greater average weight loss.
Side Effects Comparison
Both drugs affect the gastrointestinal system, so side effects are quite similar:
- Common side effects: nausea, vomiting, diarrhoea, constipation, and abdominal pain.
- Usually mild to moderate and often reduce over time with continued treatment.
- Rare but serious
Because of their similar side effect profiles, neither drug stands out as clearly safer or riskier in this aspect.
Price Comparison
In the UK, medication costs can vary depending on factors like dosage, brand, and pharmacy. Current approximate monthly prices (2026) are:
- Mounjaro: from around £133 per month.
- Wegovy: from around £89.99 per month.
While Wegovy is less expensive month-to-month, the difference in effectiveness can change the overall value.
Cost Per Kg of Weight Lost
To understand value, consider how much each kilogram of weight loss costs over a course of treatment:
- Mounjaro: Assuming average weight loss of 22.5%, the cost per kg often works out better than Wegovy despite the higher monthly price.
- Wegovy: With ~15% weight loss, the total cost per kg lost tends to be higher if effectiveness is taken into account.
In other words, you generally get more weight loss per pound spent with Mounjaro, though individual responses vary greatly.
NHS Availability Comparison
As of 2026, the availability of these medications on the NHS depends on strict criteria because of cost-effectiveness considerations:
- Mounjaro: Recently appraised by NICE, it is not yet routinely commissioned for weight management in England, mostly available through private prescription or selected specialist clinics. Some NHS trusts might provide access via individual funding requests where criteria are met.
- Wegovy: Has NICE approval since 2024 for adults with obesity (BMI ≥30 kg/m2 or ≥27 kg/m2 with comorbidities) in combination with a specialist weight management programme. It is increasingly accessible via NHS prescriptions under
Medically Reviewed by Kerris Lacy
This content has been reviewed for medical accuracy by Kerris Lacy, a qualified healthcare professional. Information provided is for educational purposes only.