Comparison
Semaglutide compared with tirzepatide.
Ozempic, Wegovy and Mounjaro are often compared as if one is simply better. The honest answer is that they work differently, suit different people, and both need medical assessment before use.
In short
Semaglutide (Ozempic, Wegovy) acts on the GLP-1 receptor. Tirzepatide (Mounjaro) acts on both the GIP and GLP-1 receptors, and has produced greater average weight loss and glucose improvement in trials. Both are weekly prescription injections, both cause mainly gastrointestinal side effects, and both work best alongside adequate protein, resistance training and sleep. The better option for an individual depends on medical history, tolerance, coexisting conditions and availability, decided at clinical assessment.
Medically reviewed by Dr Arnav Kapur, MBBCh Cum Laude
The approach
Understand first. Then treat.
Both medicines belong to the incretin class, which mimics gut hormones released after eating. They reduce appetite, slow gastric emptying and improve how the body handles glucose.
The differences that matter clinically are mechanism, average magnitude of effect, tolerance and individual suitability. None of these make one medicine universally correct.
The practical differences
- Mechanism: semaglutide targets GLP-1, tirzepatide targets GIP and GLP-1
- Average weight loss: higher in tirzepatide trials, with wide individual variation
- Glucose control: both improve HbA1c, with larger average reductions reported for tirzepatide
- Side effects: predominantly nausea, reflux and constipation for both, usually dose related
- Dosing: both weekly, both titrated gradually over months
- Availability: specific brands and strengths vary in South Africa over time
Why the bigger number is not automatically the right choice
Trial averages describe populations, not people. Tolerance, existing gastrointestinal or gallbladder disease, diabetes status, other medicines, cost, availability and how you actually respond all shape the decision. Some people do very well on semaglutide and never need to change.
What both medicines do not do
Neither corrects an underactive thyroid, insulin resistance driven by poor sleep, perimenopausal metabolic change, low testosterone, chronic stress or inadequate protein and training. Treating those makes either medicine work better and makes the result easier to keep.
How we decide
We assess history and examination, run metabolic bloods and body composition analysis, screen for contraindications, then select and titrate treatment with you. Choice is reviewed on response and tolerance rather than fixed at the first appointment.
Medicines still in development
Further incretin-based medicines are still in clinical trials and are not registered or available for prescription. We only use medicines that are registered and legitimately available, and we are clear about where the evidence currently stands.
Common questions
Answers before you book.
Which loses more weight, Ozempic or Mounjaro?
Tirzepatide has produced greater average weight loss in trials. Individual results vary substantially, and the appropriate medicine for you is determined clinically.
Are the side effects different?
The profile is broadly similar, mainly gastrointestinal, and is usually dose related. Tolerance differs between individuals, which is one reason switching is sometimes appropriate.
Can I take either without a prescription?
No. Both are prescription medicines. Products bought outside the regulated supply chain carry real risks of counterfeiting, incorrect dosing and harm.
This page is general health information about prescription medicines and is not medical advice, a prescription or an offer to supply. Treatment follows individual clinical assessment, and no outcome is guaranteed.
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Centre of Advanced Medicine, 13 Scott St, Waverley, Johannesburg
Monday to Friday, 07:40 to 17:00
011 440 8721