Mounjaro vs Wegovy: Which Weight-Loss Injection Is Better?
Mounjaro weight-loss injections contain tirzepatide and act on both GIP and GLP-1 receptors. Wegovy weight-loss injections contain semaglutide and act on GLP-1 receptors. Both reduce appetite and support weight management alongside a reduced-calorie diet and increased physical activity, but their dose schedules, evidence and prices differ.
Mounjaro vs Wegovy at a Glance
| Factor | Mounjaro | Wegovy |
|---|---|---|
| Active ingredient | Tirzepatide | Semaglutide |
| How it works | GIP and GLP-1 receptor agonist | GLP-1 receptor agonist |
| How often it is used | Once weekly | Once weekly |
| Starting dose | 2.5 mg once weekly | 0.25 mg once weekly |
| Licensed maintenance doses | 5 mg, 10 mg or 15 mg once weekly; intermediate 7.5 mg and 12.5 mg doses are used during escalation | 2.4 mg once weekly; 7.2 mg may be considered for eligible adults with obesity after at least four weeks on 2.4 mg |
| Direct comparative evidence | 20.2% average weight loss at 72 weeks | 13.7% with semaglutide 2.4 mg in the same trial |
| Common side effects | Nausea, diarrhoea, vomiting, constipation and abdominal symptoms are common with both | |
Which Produces More Weight Loss?
SURMOUNT-5 is the most useful study for a direct Mounjaro vs Wegovy comparison. It randomised 751 adults with obesity but without type 2 diabetes to the maximum tolerated dose of tirzepatide or semaglutide. At 72 weeks, average weight loss was 20.2% with tirzepatide and 13.7% with semaglutide. The study compared tirzepatide with semaglutide doses up to 2.4 mg.
STEP UP separately studied Wegovy 7.2 mg in adults with obesity. Using the treatment-policy analysis, average weight loss at 72 weeks was 18.7% with 7.2 mg, 15.6% with 2.4 mg and 3.9% with placebo. These results show that 7.2 mg can produce more average weight loss than 2.4 mg in that study, but they do not establish whether Mounjaro or Wegovy 7.2 mg is more effective for an individual patient.
How the Dose Schedules Differ
Mounjaro dosing
Mounjaro starts at 2.5 mg once weekly for four weeks, then usually increases to 5 mg. Further 2.5 mg increases may be prescribed after at least four weeks at the current dose, up to 15 mg once weekly. The best dose is the one your prescriber selects based on response and tolerability. See the Mounjaro dose schedule for the full escalation pathway.
Wegovy dosing
Wegovy starts at 0.25 mg once weekly and usually increases every four weeks through 0.5 mg, 1 mg and 1.7 mg to the standard 2.4 mg maintenance dose. For eligible adults with obesity, 7.2 mg may be considered if needed after at least four weeks on 2.4 mg. Doses above 2.4 mg are not recommended for people with type 2 diabetes or adolescents. See the Wegovy dose schedule.
Both medicines are injected under the skin once weekly. Their milligram doses are not equivalent, so one medicine's dose cannot be converted directly into the other. Our Mounjaro and Wegovy injection guide explains the pen-specific steps.
Mounjaro vs Wegovy Side Effects
Both treatments commonly cause digestive effects, particularly when treatment starts or the dose increases. The most frequent include nausea, diarrhoea, vomiting, constipation and abdominal discomfort. Individual tolerability matters more than assuming one medicine will always feel easier than the other.
Before increasing a dose
Tell your prescriber about continuing or troublesome symptoms. Dose escalation may need to be delayed or reviewed. Read the Mounjaro side effects guidance for warning signs and practical steps.
When using Wegovy
Digestive effects are also common with semaglutide. Wegovy 7.2 mg has additional licensed safety information that your prescriber will consider. Read the Wegovy side effects guidance.
Severe, persistent abdominal pain, a serious allergic reaction, inability to keep fluids down or sudden sight loss needs urgent medical assessment. Follow the leaflet supplied with your medicine and the urgent-care advice in the relevant side-effects guide.
How Much Do Mounjaro and Wegovy Cost?
Prices depend on the prescribed dose and whether you choose a subscription or single purchase. The prices below are Happy Pharmacy prices per four-week pack, checked 4 October 2026. They are shown for comparison and can change.
| Treatment and dose | Subscription | Single purchase |
|---|---|---|
| Mounjaro 2.5 mg starting dose | £134.99 | £149.99 |
| Mounjaro 15 mg highest dose | £287.99 | £319.99 |
| Wegovy 0.25 mg starting dose | £89.99 | £99.99 |
| Wegovy 2.4 mg standard maintenance dose | £188.99 | £209.99 |
| Wegovy 7.2 mg higher-dose option | £233.99 | £259.99 |
Doses are not equivalent, and the highest dose is not automatically the right dose. Before you buy Mounjaro online, check the current price at your prescribed strength and compare it with Wegovy prices. The Mounjaro cost guide explains how prices change during titration.
Which Treatment May Be More Suitable?
There is no universally better choice. A prescriber assesses your health history, other medicines, previous treatment, response, side effects and preferences. Factors commonly discussed include:
- Expected benefit: Mounjaro produced greater average weight loss than Wegovy 2.4 mg in SURMOUNT-5, but individual results vary.
- Current response: someone doing well on a tolerated treatment may not benefit from changing solely because another trial average is higher.
- Eligibility for Wegovy 7.2 mg: it is an option only for eligible adults with obesity when needed after time on 2.4 mg; it is not the default maintenance dose.
- Side effects and medical history: suitability and dose progression require individual review.
- Cost and availability: the price changes by dose and may affect long-term treatment decisions.
If you are considering a change, read the guide to switching from Mounjaro to Wegovy. Do not overlap the medicines or select a new starting dose yourself.
Frequently Asked Questions
Is Mounjaro better than Wegovy for weight loss?
Mounjaro produced greater average weight loss than Wegovy 2.4 mg in the direct SURMOUNT-5 trial: 20.2% versus 13.7% at 72 weeks. Wegovy 7.2 mg produced 18.7% average weight loss in a separate trial and has not been directly compared with Mounjaro. Suitability and individual results vary.
Is Wegovy 7.2 mg the usual maintenance dose?
No. Wegovy 2.4 mg once weekly is the standard maintenance dose. For eligible adults with obesity, a prescriber may increase it to 7.2 mg if needed after at least four weeks on 2.4 mg. Doses above 2.4 mg are not recommended for patients with type 2 diabetes or adolescents.
Is Mounjaro cheaper than Wegovy?
It depends on the dose and purchase option. At Happy Pharmacy on 4 October 2026, Wegovy had the lower starting price, while prices at later doses varied. Compare the dose your prescriber recommends rather than comparing only the highest strengths.
Can I switch between Mounjaro and Wegovy?
A prescriber may recommend switching, but the medicines should not be used together and their doses are not equivalent. The timing and new starting dose depend on your treatment history, response and side effects.
Do Mounjaro and Wegovy have the same side effects?
They share common digestive side effects, including nausea, diarrhoea, vomiting, constipation and abdominal discomfort. Their full safety information is not identical, and individual tolerability varies. Read the supplied leaflet and discuss symptoms with your prescriber.
Compare Your Treatment Options
Complete an online consultation for assessment by a UK-registered prescriber. Treatment is supplied only when it is clinically suitable.
Start Your ConsultationView WegovySources
- New England Journal of Medicine: tirzepatide compared with semaglutide for obesity
- UK Mounjaro KwikPen prescribing information
- UK Wegovy 7.2 mg prescribing information and STEP UP results
This guide provides general information and does not replace the patient leaflet or personalised clinical advice.