| TL;DR Wegovy (semaglutide) and Mounjaro (tirzepatide) are the two leading prescription weight loss injections in the UK in 2026. Mounjaro acts on two hormonal pathways (GLP-1 and GIP) and has produced greater average weight loss (around 20%) in clinical trials. Wegovy acts on GLP-1 alone and now achieves comparable results at the new 7.2mg dose approved in January 2026. Following Eli Lilly’s September 2025 price increase, Wegovy is now generally the more affordable option across most dose levels. |
The UK weight loss landscape has changed rapidly, with injectable treatments like Wegovy and Mounjaro now at the centre of clinical and patient conversations. As demand rises, so does the key question: which treatment is actually right for you?
This guide breaks down Wegovy vs Mounjaro UK in 2026, looking at how each medication works, how much they cost, and who they are best suited for. Instead of oversimplifying the decision, it gives you a practical understanding so you can choose the most appropriate treatment with professional guidance.
What Are Wegovy and Mounjaro?
Both Wegovy and Mounjaro are once-weekly injectable medications administered via a pre-filled injector pen. Both are licensed in the UK for weight management in adults with a BMI of 30 or above, or 27 or above with at least one weight-related health condition.
Wegovy contains semaglutide, a GLP-1 receptor agonist manufactured by Novo Nordisk. It was approved by the MHRA in the UK for weight management in 2023 and received NICE approval for use in specialist NHS services in the same year. The standard maintenance dose is 2.4mg weekly, and a higher dose of 7.2mg was approved by the MHRA in January 2026.
Mounjaro contains tirzepatide, a dual GIP and GLP-1 receptor agonist manufactured by Eli Lilly. It was approved by the MHRA in 2023. It offers six dose levels (2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg), with the maximum maintenance dose being 15mg weekly. NICE approved Mounjaro for NHS use in weight management in 2024.
Wegovy vs Mounjaro 2026: How They Work Differently
Understanding the mechanism of action is important because it explains why these two medications produce different outcomes in different individuals.
Wegovy (semaglutide): GLP-1 receptor agonist
GLP-1 (glucagon-like peptide-1) is a hormone produced in the gut after eating. Semaglutide mimics this hormone, producing the following effects:
- Stimulates insulin release
- Suppresses glucagon
- Slows gastric emptying
- Reduces appetite
- Increases feelings of fullness
It is a weekly injection with a new 7.2mg dose approved in 2026.
Mounjaro (tirzepatide): Dual GIP and GLP-1 receptor agonist
By acting on both GLP-1 and GIP pathways simultaneously, tirzepatide creates a broader metabolic signal that appears to produce stronger appetite suppression and greater weight loss in most patients.
- Dual GLP-1 + GIP agonist
- Stronger metabolic effect
- Weekly injection
- More dose flexibility
Mounjaro vs Wegovy Results: What the Clinical Trials Show
STEP 1 Trial (Wegovy 2.4mg)
The STEP 1 trial participants on semaglutide 2.4mg lost an average of 14.9% of their body weight over 68 weeks, compared to 2.4% with placebo. Around 69% of participants achieved at least 10% weight loss.
SURMOUNT-1 Trial (Mounjaro)
The SURMOUNT-1 trial demonstrated that tirzepatide at doses of 5mg, 10mg, and 15mg produced average weight loss of 15%, 19.5%, and 20.9%, respectively, over 72 weeks, compared to 3.1% with placebo. These results were substantially larger than those seen with Wegovy in the STEP trials at comparable timepoints.
SURMOUNT-5 Trial: The First Direct Head-to-Head
The most clinically significant development in the Wegovy vs Mounjaro 2026 comparison is the SURMOUNT -5 trial, published in the New England Journal of Medicine in 2025. This was the first direct head-to-head randomised controlled trial comparing tirzepatide with semaglutide for weight loss.
The results clearly favoured tirzepatide at the then-standard maximum doses: participants on Mounjaro 15mg lost an average of 20.2% of their body weight, compared to 13.7% for those on Wegovy 2.4mg. Approximately 45% of Mounjaro participants achieved at least 25% weight loss, compared to 19% of Wegovy participants.
STEP UP Trial: The New Wegovy 7.2mg Dose
In January 2026, the MHRA approved a higher dose of Wegovy, 7.2mg weekly, based on data from the STEP UP trial. This investigational dose produced an average weight loss of 20.7% over 72 weeks, bringing Wegovy’s top-end efficacy essentially in line with Mounjaro’s 15mg dose. The gap between the two medications at their respective maximum doses has now largely
Wegovy vs Mounjaro Side Effects
Both medications share similar side effects due to GLP-1 action:
Common side effects:
- Nausea
- Vomiting
- Diarrhoea
- Constipation
- Reduced appetite
Key Difference
- Mounjaro may affect absorption of oral medications (e.g. contraceptive pill)
- Slightly lower discontinuation rate in trials
Both medications can be associated with more serious risks. These include pancreatitis (severe abdominal pain), gallbladder disease, kidney problems linked to dehydration, and severe allergic reactions. There is also a precautionary risk of thyroid tumours, meaning these treatments are not suitable for individuals with a history of medullary thyroid cancer or MEN2 syndrome.
Mounjaro vs Wegovy Dosage Comparison
| Feature | Wegovy (Semaglutide) | Mounjaro (Tirzepatide) |
| Mechanism | GLP-1 receptor agonist | Dual GLP-1 and GIP agonist |
| Dose increments | 5 (0.25, 0.5, 1.0, 1.7, 2.4mg) | 6 (2.5, 5, 7.5, 10, 12.5, 15mg) |
| Maximum licensed dose | 7.2mg (MHRA Jan 2026) | 15mg |
| Time to full dose | Approximately 17 weeks | Approximately 20-24 weeks |
| Injection frequency | Once weekly | Once weekly |
| NICE approved for NHS | Yes (specialist services only) | Yes (limited rollout) |
Are Wegovy and Mounjaro Available in the UK?
Both medications are available in the UK, primarily via private prescription. NHS access exists for both, but is limited.
NHS access to Wegovy: NICE approved Wegovy for use within specialist NHS weight management services in 2023, for patients with a BMI of 35 or above (or 30 or above with comorbidities). Access is limited by available service capacity, and waiting times are extended in many areas.
NHS access to Mounjaro: NICE approved Mounjaro for NHS weight management in 2024. NHS rollout is being phased, with broader commissioning expected from around mid-2026. Currently, most patients accessing Mounjaro for weight management do so privately.
Private access to both: Both medications are available immediately via private prescription from GPhC-registered UK pharmacies and online prescribing services, subject to a clinical assessment confirming eligibility.
Which is Better: Wegovy or Mounjaro?
Choose Mounjaro if:
- You want maximum weight loss at standard doses
- You did not respond well to semaglutide
- You prefer more dosing flexibility
Choose Wegovy if:
- Cost is important
- You want proven cardiovascular benefits
- You prefer a well-established GLP-1 treatment
- You may benefit from the 7.2mg dose
Conclusion
In 2026, the choice between Wegovy and Mounjaro is not about one being clearly better than the other. Mounjaro may lead to slightly more weight loss at standard doses, but Wegovy now offers similar results at higher doses and is usually more affordable. This makes both options strong and effective, depending on what suits you best.
Speaking directly with a pharmacist at Batley Pharmacy allows you to make an informed, confident decision rather than guessing. With expert advice, ongoing monitoring, and easy access to care,
FAQs
Which is more effective between Wegovy and Mounjaro?
Clinical trial data shows Mounjaro produces greater average weight loss at standard doses (20.2% vs 13.7% in SURMOUNT-5). However, the new Wegovy 7.2mg dose achieves approximately 20.7% weight loss, largely closing the gap. Individual responses vary considerably.
Is Wegovy cheaper in 2026?
Yes. Following Eli Lilly’s September 2025 price increase for Mounjaro, Wegovy is now generally the more affordable option across most dose levels for private patients in the UK. The difference is approximately £600 to £1,100 over a full year at maintenance doses.
Is Wegovy worth it in the UK?
Yes, for eligible patients. The STEP 1 trial showed average 14.9% weight loss over 68 weeks, and the SELECT trial demonstrated a 20% reduction in major cardiovascular events. Wegovy is NICE-approved and clinically proven. Whether it is cost-effective depends on individual health goals and financial circumstances.
Why are people using Ozempic instead of Wegovy?
Ozempic (semaglutide 0.5mg-2mg) is licensed for type 2 diabetes management. Some prescribers have used it off-label for weight loss when Wegovy has been unavailable due to supply constraints, or because the patient already uses it for diabetes. Wegovy at 2.4mg is the dose approved specifically for weight management and produces greater weight loss than Ozempic doses.