People taking weight-loss jabs such as Wegovy and Mounjaro have been reminded of a crucial rule that could save them up to £300 this summer. Medications must be stored in proper conditions to preserve their active ingredients and maintain effectiveness.
Storage guidelines for Wegovy and Mounjaro
An estimated 1.6 million adults in the UK have used weight-loss injections in the past year, according to University College London. With strict NHS eligibility criteria, about nine out of 10 users currently pay privately through licensed clinics.
These injections are biological, protein-based medicines. They are extremely delicate and will deteriorate if they become too warm, potentially making the medication unsafe to use.
As some people buy this privately, it could waste a pen valued at up to £300 (for the highest doses of Wegovy). Both drugs share similar storage instructions.
For both medications, the guidance is to refrigerate unopened pens. Once opened, they can be stored outside the fridge but must adhere to strict temperature requirements.
Expert advice from Dr Kathryn Basford
Dr Kathryn Basford, at Asda Online Doctor, said: "For Mounjaro to remain effective and safe, it ideally needs to be refrigerated between 2°C and 8°C. It can be stored unrefrigerated for up to 30 days, so long as it doesn't go above 30°C."
"If your Wegovy pen is already open, it's best to store it in a refrigerator between 2°C and 8°C. However, you can store it outside the fridge for up to six weeks from opening as long as the temperature does not go above 30°C."
"Similar to Mounjaro, in line with the hot weather this weekend, you should refrigerate your Wegovy medication."
UK heatwave forecast
This weekend, the Met Office is forecasting warmer and drier conditions across the UK. Deputy Chief Meteorologist Steven Keates said: "From this weekend, the UK forecast will have a distinctly warmer and drier component with a prolonged spell of above-average temperatures."
"Values in some locations quite likely to reach 27°C to 29°C, with the potential for higher values than this." Met Office forecasters expect this warm spell to extend well into the following week at least.
Dehydration risk in hot weather
Those taking weight loss medication should also be mindful of another significant concern that can go unnoticed in the heat. Dr Basford warned that people using GLP-1s such as Mounjaro or Wegovy during hot weather may experience dehydration as a potential side effect.
The doctor explains that, because the injections suppress appetite, they also "blur your thirst response", meaning you could be far thirstier than you actually realise.
She said: "During a heatwave, your body loses more water than usual through sweating, meaning it's even easier to become dehydrated. Keep on top of your water intake, aiming for around three litres, staggered throughout the day. A good way to do this is to keep a water intake diary, or purchase a bottle with daily intake targets visible."
