What new weight loss drugs are in development for 2026?
Results are in for retatrutide, orforglipron and CagriSema. But are they as effective as Wegovy and Mounjaro? Find out in our guide.
The injectable weight loss medications Wegovy and Mounjaro have been available in the UK for several years. And they're still the most effective treatments of their kind on the market.
As we move into a new year, however, it's natural to ask, 'What's next?'
With phase 3 trials underway for three similar weight loss medications, we might not have to wait long to find out.
Let's explore some of the latest information on these new medications, as well as how they stand up to tried-and-tested treatments like Wegovy and Mounjaro.
Retatrutide
Wegovy is a single hormone receptor agonist. It mimics an important gut hormone called 'GLP-1'.
Mounjaro is a dual agonist. It mimics GLP-1, as well as another hormone called 'GIP'.
Well, retatrutide has them both beaten – at least on quantity alone. It's the world's first triple agonist of its kind, mimicking GLP-1, GIP and the blood sugar hormone glucagon.
Combining all three aims to:
- Suppress appetite (GLP-1)
- Improve insulin action (GLP-1 and GIP)
- Increase calorie burning and fat loss (glucagon)
It's hoped that the triple mechanism will be even more helpful for weight loss compared to single- or dual-agonist drugs like Wegovy or Mounjaro. Early findings from clinical trials suggest it might.
In a phase 2 trial, 83% of people who took retatrutide saw weight loss of 15% or more, and 100% saw at least 5% weight loss.¹ That's a promising start.
Now, with the phase 3 TRIUMPH programme, researchers are further exploring its potential benefits for weight loss.
The TRIUMPH programme
Eli Lilly, the company behind retatrutide, is currently assessing the drug in a phase 3 trial programme known as 'TRIUMPH'. Across four separate trials, the programme will assess the drug for weight loss, sleep apnoea and knee osteoarthritis in people living with obesity or overweight.
Phase 3 trials commonly test things like dosage and include many more participants than phase 2 studies. In the case of TRIUMPH, around 5,800 people from several countries will test 4mg, 9mg and 12mg doses of retatrutide. That means we'll have plenty of data from different population groups – and in medicine, the more varied the data, the better.
What we know so far – and when we'll know more
The TRIUMPH researchers are expected to publish some of their findings in 2026 and 2027.
As of now, we have early results from the TRIUMPH-4 study, which looks at the drug's potential benefits for knee osteoarthritis. This is a common health issue among people living with obesity.
These early results are very promising. After 68 weeks, participants taking 12mg of retatrutide:²
- Reported a 75.8% improvement in pain scores. More than 1 in 8 retatrutide users said they were completely free of knee pain by the trial's end.
- Saw an average weight loss of 28.7%. That's around 14% more than Wegovy's average and 8% more than Mounjaro's.³ ⁴
As with Wegovy and Mounjaro, side effects have been mostly mild and manageable. Nausea, diarrhoea and constipation are among the most common.²
Between 9% and 20% of people experienced dysesthesia (itching or unusual sensations in the skin) when taking retatrutide. So far, this side effect also seems to be relatively mild and, in the study, rarely led to discontinuation of treatment.²
CagriSema
CagriSema has been developed by Novo Nordisk, the company behind Wegovy. It combines two powerful medications into one injection:
- Semaglutide: the active ingredient in Wegovy, which mimics the body's GLP-1 hormone.
- Cagrilintide: this new medication is an amylin analogue, meaning it mimics another digestive hormone called 'amylin'. This hormone is involved in many of the same bodily functions as GLP-1.
The theory is that the two medications will work together to trigger weight loss more effectively than semaglutide alone.
We've previously explored the outcomes from the phase 3 CagriSema trial, which was published earlier this year. There, CagriSema users experienced an average weight loss of 20.4%.⁵ That's 5.5% more than semaglutide (Wegovy) alone,³ 9.6% more than cagrilintide alone,⁶ and just a little shy of Mounjaro's average of 20.9%.⁴
Even more impressive results have emerged since we last discussed CagriSema. According to a recent Novo Nordisk press release, CagriSema achieved an average of 23% weight loss 'when evaluating the treatment effect if all patients stayed on treatment'.⁷
Will CagriSema be available soon?
Novo Nordisk has submitted CagriSema for FDA approval, which is expected to be reviewed in 2026.⁷ That means injectable CagriSema may be available in the US as an alternative to Wegovy and Mounjaro in the not-too-distant future.
There are a number of other Phase 3 trials still ongoing. These include:
- REDEFINE 3, which looks at heart-related conditions⁸
- REDEFINE 11, which looks specifically at the impact CagriSema may have over a longer timeframe for patients with a BMI of 30 or greater⁹
Orforglipron
Orforglipron – also made by Eli Lilly – is a little different to our other examples. That's because it's taken orally (as a pill) rather than injected. It's also taken once daily instead of once each week.
We've previously looked at the results from the ATTAIN-1 clinical trial. In this study, participants lost 11.2% of their body weight on average when taking a 36mg dose of orforglipron over 72 weeks.¹⁰
Orforglipron appears to be less effective than Wegovy (15%)³ and Mounjaro (21%).⁴ However, these results show it could offer a viable alternative for people who can't use injections.
There's hope that it can be useful for maintaining weight after using injections, too.
Eli Lilly has asked the FDA to approve orforglipron for weight loss, and it has been selected for the National Priority Review Voucher pilot program.¹¹ Potentially, this means that it could reach the US market soon.
When will these medications be available in the UK?
It's still too early to say whether retatrutide, CagriSema or orforglipron will be approved in the UK, or when, or what they might cost.
For now, people who are looking for an effective weight loss medication can rely on several approved treatments, depending on their unique needs.
Wegovy and Mounjaro are both available from reputable providers like SemaPen. When combining the medications with a healthy lifestyle and the support of our experts, users can expect to lose between 15%³ and 21%⁴ of their starting weight.
Want to learn more? You can simply take our digital consultation to find out which option might be best for your needs.
Sources
1. Jastreboff, A.M. et al. (2023) "Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial" The New England Journal of Medicine, 389(6) https://doi.org/10.1056/NEJMoa2301972
2. Eli Lilly and Company (2025) Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial [press release]. Retrieved from https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-delivered-weight-loss-average
3. Wilding, J.P.H. et al. (2021) "Once-weekly semaglutide in adults with overweight or obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183
4. Jastreboff, A.M. et al. (2022) "Tirzepatide Once Weekly for the Treatment of Obesity" The New England Journal of Medicine, 387(3) https://doi.org/10.1056/NEJMoa2206038
5. Garvey, W.T. et al. (2025) "Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity" The New England Journal of Medicine, 393(7) https://doi.org/10.1056/NEJMoa2502081
6. Lau, D.C.W. et al. (2021) "Once-weekly cagrilintide for weight management in people with overweight and obesity: a multicentre, randomised, double-blind, placebo-controlled and active-controlled, dose-finding phase 2 trial" The Lancet, 398(10317) https://doi.org/10.1016/S0140-6736(21)01751-7
7. Novo Nordisk (2025) Novo Nordisk files for FDA approval of CagriSema, the first once-weekly combination of GLP-1 and amylin analogues for weight management [press release]. Retrieved from https://www.novonordisk.com/content/nncorp/global/en/news-and-media/news-and-ir-materials/news-details.html?id=916470
8. National Library of Medicine (2025) REDEFINE 3: A Research Study to See the Effects of CagriSema in People Living With Diseases in the Heart and Blood Vessels (REDEFINE 3). Retrieved from https://clinicaltrials.gov/study/NCT05669755
9. Barrie, R. (2025) Novo Nordisk plans new study for CagriSema, targets 2026 submission. Pharmaceutical Technology. Retrieved from https://www.pharmaceutical-technology.com/news/novo-nordisk-plans-new-study-for-cagrisema-targets-2026-submission/
10. Wharton, S.W. et al. (2025) "Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment" The New England Journal of Medicine, 393(18) https://doi.org/10.1056/NEJMoa2511774
11. Eli Lilly and Company (2025) What to know about orforglipron: An investigational oral GLP-1. Retrieved from https://www.lilly.com/news/stories/what-to-know-about-orforglipron
This article was reviewed and approved by Lujain Alhassan, Bariatric Dietitian, and Sarah Abdula, Specialist Dietitian, on 5 January 2026.
