WEIGHT LOSS
Mounjaro vs Wegovy: What Is the Difference?
Why the comparison should start with clinical suitability rather than brand preference, and how to approach the decision properly.
Mounjaro and Wegovy are two of the most commonly discussed medicines in private weight management, and many patients arrive at a consultation already comparing them. Both are injectable medicines administered once weekly. Both can produce clinically significant weight loss in appropriate patients. But they are not the same medicine, and the decision between them depends on clinical suitability, not brand preference.
Suitability depends on medical history, current weight, previous treatments, side-effect profile, co-existing conditions, and how the treatment is going to be monitored. Neither medicine removes the need for proper clinical review.
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How Wegovy works
Wegovy contains semaglutide and acts on the GLP-1 receptor. It reduces appetite, slows gastric emptying, and helps patients feel satisfied with less food. It is licensed for weight management in adults with a BMI of 30 or above, or 27 or above with at least one weight-related condition. The dose is titrated gradually over several weeks to reduce gastrointestinal side effects, starting at 0.25mg and increasing to the maintenance dose of 2.4mg weekly. Trial data has shown mean weight loss of approximately 15% of body weight, though individual results vary considerably.
How Mounjaro works
Mounjaro contains tirzepatide and acts on both the GLP-1 and GIP receptors — a dual-action mechanism. Like Wegovy, it reduces appetite and slows gastric emptying, but the additional GIP pathway may contribute to improved glucose metabolism and potentially greater weight loss in some patients. It is also dose-titrated, starting at 2.5mg and increasing in steps. Trial data has shown mean weight loss of approximately 20–25% of body weight at higher doses, though again individual response varies and not all patients reach the maximum dose.
Comparison
The differences that actually matter
The most clinically important differences are mechanism (single vs dual receptor), titration schedule, side-effect profile, and how each medicine fits the individual patient’s medical background. Both can cause gastrointestinal side effects — nausea, reduced appetite, constipation, diarrhoea and reflux — but the pattern and intensity may differ. The prescribing decision should take into account diabetes status, cardiovascular history, pancreatitis risk, gallbladder history, pregnancy plans, and how the patient has responded to previous weight-management treatments. Availability can also be a practical factor.
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Clinical decision
Why the consultation matters more than the brand
Patients sometimes arrive having decided which medicine they want before being assessed. That is understandable given the volume of online discussion, but it is not the safest approach. Baseline blood tests, a proper medical history, a review of contraindications, and an honest discussion about expectations should come before any prescribing decision. At Basuto, the weight loss consultation is designed to assess suitability first and then discuss which treatment route — if any — makes most clinical sense.
Common questions
How do Mounjaro and Wegovy differ clinically?
Wegovy contains semaglutide and acts on the GLP-1 receptor. Mounjaro contains tirzepatide and acts on both GLP-1 and GIP receptors — a dual-action mechanism. Both are injectable, weekly, and titrated gradually. The differences in mechanism, titration schedule and side-effect pattern affect which medicine suits a given patient.
Does one medicine produce more weight loss than the other?
Clinical trial averages have shown approximately 15% mean weight loss with semaglutide and 20–25% with tirzepatide at higher doses. Individual response varies considerably. Trial averages are not individual promises, and not every patient reaches the maximum dose. Tolerability and suitability matter at least as much as headline numbers.
How is the choice between them decided?
Through a clinical consultation that reviews medical history, current weight, co-existing conditions, contraindications, previous treatments and availability. Neither medicine removes the need for proper assessment. Patients sometimes arrive with a preferred brand, but suitability — not preference — determines the prescribing decision.
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