Compare treatments
Mounjaro vs Wegovy vs Saxenda
All three are prescription-only injections licensed in the UK for weight management, and all three reduce appetite by mimicking gut hormones. Mounjaro acts on two receptors rather than one, and in the only head-to-head trial produced greater average weight reduction than Wegovy. Saxenda is injected daily rather than weekly. Which is appropriate is a clinical judgement, not a ranking.
The head-to-head trial
Most comparisons between these treatments set separate trials side by side, which is unreliable because trial populations differ. SURMOUNT-5 compared them directly in the same study, and was published in the New England Journal of Medicine. It is the closest thing to an answer on which is the most effective weight loss injection, and it answers that for a trial population rather than for you.
−20.2%
Mean body weight reduction · 22.8 kg average
−13.7%
Mean body weight reduction · 15.0 kg average
751 adults, 72 weeks, maximum tolerated doses of each. Participants had a BMI of 30 or above, or 27 or above with a weight-related condition, and did not have type 2 diabetes. Tirzepatide also produced greater improvements in blood pressure, HbA1c, fasting insulin, triglycerides and HDL cholesterol.
Read averages carefully. A mean result describes a trial population, not a person. Individual response varies widely, some people tolerate one treatment better than another, and the treatment that suits you is the one a prescriber judges appropriate after reviewing your full history.
Which is the best weight loss medication, side by side
| Feature | Mounjaro | Wegovy | Saxenda |
|---|---|---|---|
| Active ingredient | Tirzepatide | Semaglutide | Liraglutide |
| Receptors targeted | GIP and GLP-1 | GLP-1 only | GLP-1 only |
| Frequency | Once weekly | Once weekly | Once daily |
| Dose range | 2.5–15 mg | 0.25–2.4 mg | 0.6–3.0 mg |
| Time to maintenance dose | From 20 weeks | From 16 weeks | From 5 weeks |
| UK licensing | Weight management | Weight management | Weight management |
Ozempic is deliberately absent from this table. It contains semaglutide but is licensed for type 2 diabetes, not weight management, so comparing it here as a weight loss treatment would misrepresent its licence.
Common questions
Is Mounjaro better than Wegovy?
In the SURMOUNT-5 trial, the first direct comparison of the two, tirzepatide produced a greater mean weight reduction than semaglutide: 20.2% against 13.7% across 72 weeks. That is an average across a trial population, not a prediction for any individual. Tolerability, other conditions and existing medicines all bear on which treatment is appropriate, and that decision belongs to a prescriber.
What is the difference between Mounjaro and Wegovy?
Mounjaro contains tirzepatide and acts on two gut hormone receptors, GIP and GLP-1. Wegovy contains semaglutide and acts on GLP-1 alone. Both are once-weekly injections licensed in the UK for weight management. The dual mechanism is the principal pharmacological difference between them.
Is Ozempic the same as Wegovy?
Both contain semaglutide, but they are licensed for different purposes and at different doses. Wegovy is licensed for weight management. Ozempic is licensed for type 2 diabetes, and its use for weight loss is off-label. They are not interchangeable.
Why is Saxenda taken daily when the others are weekly?
Liraglutide has a shorter duration of action than semaglutide or tirzepatide, so it requires daily injection to maintain its effect. The weekly treatments are engineered to resist breakdown for longer. Daily dosing is the main practical difference people notice.
Sources
- SURMOUNT-5: greater loss of weight and waist circumference with tirzepatide than semaglutide · American College of Cardiology
- Tirzepatide for managing overweight and obesity (TA1026) · NICE
- Mounjaro Summary of Product Characteristics · electronic medicines compendium
Awaiting sign-off by a named clinician.
A mean result describes a trial population, not a person. Individual response varies widely, so the average tells you what happened across a study rather than what will happen to you.
Comparisons inform the conversation; they do not replace it. A prescriber decides which treatment is appropriate based on your history, other conditions and existing medicines.
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