The cost of the Mounjaro weight loss drug is set to rise sharply in the UK from 1 September, although a discount scheme agreed with suppliers will limit the increase for patients.
Manufacturer Eli Lilly had announced earlier this month that the list price of Mounjaro would go up by as much as 170%. That would have taken the cost of the highest 15mg dose from £122 to £330 per month. A new arrangement now means the top dose will be sold to suppliers for £247.50, softening the rise but still leaving patients paying significantly more than before.
Private providers such as high street pharmacies and online clinics will set their own mark-ups, so the final cost to patients will vary. The BBC has reported that some services expect the rise for higher doses to be kept under 50%, while increases for lower doses may be smaller still.
Eli Lilly confirmed the rebate scheme in a statement, saying: “We are working with private providers on commercial arrangements to maintain affordability and expect these to be passed onto patients when the change is effective on 1 September.” The company added that different providers are already responding with a variety of pricing options.
The deal does not affect NHS patients, as the health service has negotiated its own separate, heavily discounted rates. Mounjaro has been available through specialist NHS weight-loss clinics in England and Wales since March 2025, and since June some GPs in England have been able to prescribe it to eligible patients. To qualify, people must meet strict criteria including a BMI of 40 or more (37.5 for some minority ethnic groups) and at least four serious health conditions linked to obesity.
There are thought to be around 1.5 million people on weight loss drugs in the UK, with more than half using Mounjaro. Estimates suggest that nine in 10 buy privately rather than through the NHS, often through online providers. For them, the coming rise in the Mounjaro weight loss drug price will be felt most keenly.
The popularity of the drug stems from its effectiveness. Mounjaro is the brand name for tirzepatide, which works by mimicking hormones that regulate appetite and metabolism. Weekly injections help users feel full, reduce food cravings and can lead to a 20% reduction in body weight over a 72-week treatment period. Clinical trials show it is more effective than rival drug Wegovy, which generally leads to around 14% weight loss in the same timeframe.
However, doctors caution that the benefits only last as long as the medication is taken. Research shows that many people put weight back on within a year of stopping treatment, as their appetite and eating habits return. Experts have therefore urged the NHS to ensure patients are given regular check-ups, exercise support and healthy eating plans alongside prescriptions.
Thames Gazette spoke to one GP who said “When you are purchasing and using a drug like this, make sure you are following things up with proper monitoring… make sure you aren’t getting any bad reactions or anything of that sort. Contact your prescriber if you are having any concerns.”
For those paying privately, affordability is becoming a serious concern. One patient told Sky News that he stockpiled two months’ worth of doses before the price rise, but feared he would not be able to continue long term. He said missing even a single week left him worried he would regain the weight he had lost.
Some pharmacies are now advising patients not to cut corners as costs rise. James Hunt, director of the online pharmacy CheqUp, warned that people should not skip doses, microdose, or turn to unregulated sources: “Absolutely do not do that,” he said. “If you’re taking a medication you need to use that medication as it’s been instructed and designed to be used clinically.”
Olivier Picard, chair of the National Pharmacy Association, said: “Pharmacies will do all they can to support patients when prices change. This rebate will mitigate some of the impact of the increase, but patients should still anticipate seeing a rise in prices from 1 September.”
Eli Lilly said the increase reflects a move to bring UK prices more in line with those in Europe and the US. Former US President Donald Trump had previously criticised the pharmaceutical industry for charging Americans more than other countries, pressuring companies to raise international prices to help offset domestic reductions.
While the discount will ease the blow, many patients relying on the Mounjaro weight loss drug will still face higher bills from next month.
Pharmacies and clinics are preparing for demand to shift, with some suggesting that patients may consider switching to Wegovy, which is likely to remain cheaper.
For now, millions in the UK who depend on these medications to manage their weight and health will be watching closely as the new pricing takes effect.
