Wegovy vs Mounjaro: Which Is Better for Weight Loss?
For years, comparisons between Wegovy and Mounjaro were made by placing results from separate clinical trials next to each other. That was useful, but it was never a completely fair comparison because the trials involved different people and were run differently.
We now have a proper head-to-head trial. In SURMOUNT-5, Mounjaro produced substantially more weight loss than standard-dose Wegovy. However, a newly licensed higher dose of Wegovy means the answer is no longer quite as simple as saying “Mounjaro gives 20% and Wegovy gives 15%.”
Farzin GhayedyAuthor · Prescribing Pharmacist
Daniel HighamReviewer · Superintendent PharmacistAt a glance
- In the SURMOUNT-5 head-to-head trial, Mounjaro produced 20.2% average weight loss versus 13.7% for Wegovy 2.4mg, a 6.5 percentage point difference.
- For a 100kg person, trial averages mean about 20kg lost with Mounjaro and 14kg with Wegovy, but these are averages, not guarantees.
- Wegovy now offers a 7.2mg weekly dose for adults with obesity, after at least four weeks on 2.4mg, improving average weight loss to 18.7% in the STEP UP trial.
- Mounjaro has not been directly compared to Wegovy 7.2mg, so it is unknown which is more effective at that higher dose.
- Wegovy has proven cardiovascular benefits, reducing heart attack, stroke, or cardiovascular death to 6.5% versus 8.0% with placebo in adults with established cardiovascular disease.
- Mounjaro may reduce oral contraceptive effectiveness; women should use a barrier method or switch to non-oral contraception for four weeks after starting and after each dose increase.
What is the difference between Wegovy and Mounjaro?
Wegovy contains semaglutide and acts on the GLP-1 receptor. Mounjaro contains tirzepatide and acts on both the GIP and GLP-1 receptors.
Both medicines reduce hunger, increase feelings of fullness and make it easier to eat less. They are injected once a week and are started at a low dose before being increased gradually.
Which produces more weight loss?
SURMOUNT-5 included 751 adults with obesity, or overweight with a weight-related health condition, who did not have type 2 diabetes. Participants were randomly assigned to the highest dose of each medicine they could tolerate.
| Treatment | Average weight loss |
|---|---|
| Mounjaro | 20.2% |
| Wegovy | 13.7% |
That is a difference of 6.5 percentage points. For someone starting at 100kg, the trial averages would work out at approximately 20kg lost with Mounjaro and 14kg with Wegovy.
People taking Mounjaro were also more likely to lose at least 10%, 15%, 20% or 25% of their starting weight. The results therefore did not just favour Mounjaro by a small or questionable margin. [1]
However, these are averages rather than promises. The study did not include people with type 2 diabetes, it was open-label and it was funded by Eli Lilly, the manufacturer of Mounjaro. It is still the best direct comparison available, but those limitations are worth knowing.
Wegovy now has a 7.2mg dose
The SURMOUNT-5 trial compared Mounjaro with Wegovy at a maximum dose of 2.4mg. Since then, the UK product information for Wegovy has been updated.
Adults with obesity who need a greater effect can now increase from Wegovy 2.4mg to 7.2mg once weekly, after spending at least four weeks on the 2.4mg dose. [2]
In the STEP UP trial, average weight loss after 72 weeks was:
| Treatment | Average weight loss |
|---|---|
| Wegovy 7.2mg | 18.7% |
| Wegovy 2.4mg | 15.6% |
| Placebo | 3.9% |
The higher dose clearly improved Wegovy’s results. However, STEP UP was a separate trial involving a different group of people. You cannot place its 18.7% result beside Mounjaro’s 20.2% result and treat it as a direct comparison.
We therefore know that Mounjaro beat Wegovy 2.4mg. We do not yet know whether Mounjaro would beat Wegovy 7.2mg in a head-to-head trial.
When might Wegovy still be the better choice?
Mounjaro has the strongest case when the main priority is achieving the greatest possible weight loss. That does not make Wegovy a poor treatment, particularly when it is already working and is well tolerated.
Wegovy also has direct cardiovascular outcomes evidence in adults with established cardiovascular disease who were overweight or living with obesity but did not have diabetes. In the SELECT trial, a heart attack, stroke or cardiovascular death occurred in 6.5% of people receiving semaglutide and 8.0% receiving placebo. Wegovy now has a specific UK indication for reducing this cardiovascular risk in that group. [3]
When it comes to contraception Mounjaro may temporarily reduce the effectiveness of oral contraception. Women using the contraceptive pill are advised to add a barrier method or change to a non-oral method for four weeks after starting Mounjaro and for four weeks after every dose increase. Wegovy does not affect the pill in the same way.
Does Mounjaro cause worse side effects?
Both medicines commonly cause nausea, diarrhoea, constipation, vomiting and abdominal discomfort. These effects tend to be most noticeable when treatment is started or the dose is increased.
The SURMOUNT-5 trial found that stomach and bowel side effects were the most common with both treatments and were mainly mild to moderate. There is no good basis for assuming that Mounjaro must cause worse side effects simply because it targets two receptors. Individual responses vary considerably. [1]
Both medicines can also cause dehydration, gallbladder problems and, uncommonly, pancreatitis. Seek urgent medical attention for severe and persistent abdominal pain, particularly if it spreads through to the back or is accompanied by vomiting. Treatment should not be restarted if pancreatitis is confirmed.
Frequently asked questions
Is Mounjaro better than Wegovy?
For average weight loss, Mounjaro was more effective than Wegovy 1.7mg or 2.4mg in the direct SURMOUNT-5 trial. It has not yet been directly compared with Wegovy 7.2mg.
Can you take Wegovy and Mounjaro together?
No. They act on overlapping pathways and should not be combined. Wegovy’s UK product information specifically advises against using it with another GLP-1 receptor agonist.
Can you switch from Wegovy to Mounjaro?
Yes, but they should not be overlapped and there is no simple equivalent dose. Your starting dose and the timing of the change should be decided by your prescriber based on your current dose, side effects and how long you have been using it.
Do you need to reach the maximum dose?
No. Mounjaro has licensed maintenance doses of 5mg, 10mg and 15mg. Wegovy normally uses 2.4mg as its maintenance dose, with 7.2mg available for adults with obesity when a greater effect is needed. Higher is not automatically better if a lower dose is already producing steady results.
References
- Aronne LJ, Horn DB, le Roux CW, Ho W, Falcon BL, Gomez Valderas E, Das S, Lee CJ, Glass LC, Senyucel C, Dunn JP. 2025. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. DOI: 10.1056/NEJMoa2416394.
- Novo Nordisk. 2026. Wegovy 2.4 mg, FlexTouch solution for injection in pre-filled pen.
- Lincoff AM, Brown-Frandsen K, Colhoun HM, Deanfield J, Emerson SS, Esbjerg S, Hardt-Lindberg S, Hovingh GK, Kahn SE, Kushner RF, Lingvay I, Oral TK, Michelsen MM, Plutzky J, Tornøe CW, Ryan DH. 2023. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. DOI: 10.1056/NEJMoa2307563.