Switching to Wegovy from Mounjaro in the UK: Is It Really Worth It?
TL;DR: Switching to Wegovy from Mounjaro Rarely the Better Deal
Switching to Wegovy from Mounjaro, you’ve seen all the hype, you’ve probably been encouraged to switch while filling out a consultation.
In the UK, both Wegovy and Mounjaro have been licensed for over a year. Yet Wegovy has never been as popular because it is more expensive, less effective, and often harder to tolerate. Recently, Eli Lilly increased the price of Mounjaro in the UK. This has led some pharmacies and clinics to encourage switching to Wegovy. However, even with the price rise, Mounjaro usually offers better weight loss results for less money overall.
Before September it Wasn’t Worth Switching to Wegovy from Mounjaro
Before the change, Mounjaro was seen as much more cost effective than Wegovy, which made it an easy choice for many UK patients. From 1st September, however, Eli Lilly increased the UK price of Mounjaro. This has narrowed the price gap with Wegovy, leaving it only a little cheaper rather than significantly better value. Some believe the decision relates to political factors and exporting pressures, which made a price adjustment easier.
It is understandable why some patients may feel inclined to switch out of principle. Still, the aim here is to focus on the clear clinical facts, not the reasons behind pricing. And the evidence continues to show meaningful differences in effectiveness and side effects between the two treatments.
Why Are UK Pharmacies Encouraging People to Switch?
Pharmacies and clinics are now pushing Wegovy more strongly. The main reason is pricing and supply contracts, not better results.
- Eli Lilly raised the UK price of Mounjaro for the 1st of September 2025.
- Pharmacies may make better margins on Wegovy, especially with promotional support.
- As a result, many patients are told to consider switching to Wegovy from Mounjaro.
But this advice is not really based on what works best. It’s based on what’s easiest for pharmacies to sell.
Wegovy vs Mounjaro in the UK: How They Compare
| Feature | Mounjaro (Tirzepatide) | Wegovy (Semaglutide) |
|---|---|---|
| UK licence | Approved for weight loss >1 year ago | Approved for weight loss >1 year ago |
| Popularity in UK | High demand, strong results | Less popular, seen as weaker |
| Mechanism | Dual action: GIP + GLP-1 | Single action: GLP-1 only |
| Weight loss (average trials) | 15–22% [1] | ~15% [2] |
| 5mg vs Wegovy 2.4mg | Mounjaro ~15–17% [1] | Wegovy ~15% [2] |
| 7.5mg vs Wegovy 2.4mg | Mounjaro ~19% [1] | Wegovy ~15% [2] |
| Side effects | Often milder, fewer discontinuations [1] | More nausea, diarrhoea, and dropouts [2] |
| Price trend UK | Price rising (Eli Lilly increase) | Still higher for weaker effect |
| Cost per % weight loss | Cheaper overall | More expensive per result |
Why Wegovy Has Never Been as Popular in the UK
Even though Wegovy was the first to launch, it quickly became clear why Mounjaro overtook it:
- Wegovy is more expensive for private patients.
- Mounjaro works better, even at half doses.
- Wegovy causes more side effects such as nausea, vomiting, and diarrhoea.
- Patients talk, and word of mouth spread that Mounjaro gives better results.
So despite a year on the market, Wegovy has never built the same popularity in UK private clinics.
The Price Rise: Why People Are Being Nudged Toward Wegovy
Eli Lilly has increased the UK list price of Mounjaro, which means pharmacies make less margin if they continue selling it at previous patient prices.
For pharmacies and clinics, pushing Wegovy may be better business.
For patients, however, Mounjaro is still cheaper per kilo lost.
In other words, you might see more ads, more pharmacist nudges, and more clinic recommendations for Wegovy, but this does not mean Wegovy is the better or cheaper weight loss treatment.
Switching to Wegovy from Mounjaro – Clinical Evidence: Why Mounjaro Still Wins
Mounjaro (SURMOUNT-1, 2022) [1]
- 5mg: ~15% weight loss
- 7.5mg: ~19% weight loss
- 10–15mg: 20–22% weight loss
Wegovy (STEP-1, 2021) [2]
- 2.4mg: ~15% weight loss
Key takeaway: Even with higher UK prices, Mounjaro 5mg or 7.5mg outperforms Wegovy 2.4mg.
Bottom Line: Should You Switch?
- Mounjaro beats Wegovy, both in effectiveness and cost per result.
- Wegovy is less popular in the UK because it’s weaker, more expensive, and harder to tolerate.
- Pharmacies and clinics push Wegovy because Mounjaro prices rose, but that doesn’t change the science.
- If you’re paying privately, you usually get better results for your money by staying on Mounjaro.
Unless your doctor has a clear medical reason, switching to Wegovy from Mounjaro is not in the patient’s best interest.
References
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. NEJM. 2022. Link
- Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overwe… or Ob… NEJM. 2021. Link
- Ludvik B, et al. Tirzepatide and improvements in glycaemic control and insulin sensitivity. Diabetes, Obesity and Metabolism. 2021. Link
