The Met Office has forecast temperatures of at least 39°C for Wednesday, prompting the Medicines and Healthcare products Regulatory Agency (MHRA) to issue urgent advice on storing medicines safely during the heatwave.
Heat Can Make Medicines Ineffective
Medical experts warn that soaring temperatures can break down the active ingredients in various medicines, including tablets, inhalers, hormone patches, insulin, and EpiPens. Most medicines require storage below 25°C to remain effective, according to the MHRA. Heat damage can also alter how much medicine the body absorbs, potentially making a usual dose either too strong or too weak.
MHRA Chief Safety Officer's Advice
Alison Cave, chief safety officer at the MHRA, said: “Let’s face it – when there’s a heatwave, most of us are focused on getting outside and enjoying it while it lasts. But it’s easy to forget that medicines left in the heat – in cars, bags, or on sunny windowsills – might not work properly when you need them.”
Where to Store Medicines
The MHRA recommends keeping medicines in the coolest part of the house, away from direct sunlight. Using a thermometer in the storage location can help ensure the temperature does not exceed 25°C, as rooms with direct sunlight can become surprisingly hot. Even bags and pockets can reach temperatures high enough to cause problems, especially if you are out all day, at a festival, or a sports event. When travelling, avoid leaving medicines in parked vehicles or warm bags; use a cool bag instead.
Special Care for Fridge-Stored Medicines
Medicines that require refrigeration, such as insulin or certain liquid antibiotics, are particularly vulnerable to heat. If left out too long or stored incorrectly, they may not work properly. The MHRA advises checking for signs of heat damage, such as changes in colour, unusual smell, altered texture, or any other visible difference. If you notice any such changes, consult your pharmacist.
Monitor Your Health and Devices
If you experience any changes in how you feel or how well your medicines seem to be working during hot weather, speak to your pharmacist or doctor. Heat and humidity can also affect some medical devices. For example, blood glucose monitors may give less reliable readings if used or stored in hot conditions. Keep devices and test strips in a cool, dry place, and follow the manufacturer's temperature guidance. If a device behaves unexpectedly, run a control check or ask your pharmacist for advice.
