Essential advice on protecting your medicines during extreme heat and staying safe this summer.
With the UK bracing for another heatwave this week, the Medicines and Healthcare products Regulatory Agency (MHRA) is reminding people that high temperatures can affect medicines and how well they work. Hot weather changes how your body responds to medications, which could impact people managing long-term conditions - but a few simple steps can help avoid problems.
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.
"Some medicines can also make you more likely to burn in the sun, feel dizzy, or get dehydrated, especially if you're taking diuetics or have a condition like asthma, heart disease, or diabetes.
"To stay safe in the heat:
- Store medicines somewhere cool, dry and out of direct sunlight - especially if you're out and about
- Know the signs of heat-related illness - stay hydrated and listen to your body
- Take extra care in the sun if your medicine makes your skin more likely to burn
"And remember, for all medicines it's important to read the leaflet and speak to a healthcare professional if you have any questions."
1. Keep medicines out of hot cars and direct sunlight
Most medicines need to be stored at temperatures below 25°C. But cars, trains and buses can heat up quickly during the summer, and rooms with direct sunlight can get much hotter than you'd think. Even bags and pockets can get warm enough to cause problems, especially if you're out all day or at a festival, sports event, or the beach.
Heat can break down the active ingredients in medicines, meaning they might not work when you need them. That includes tablets, inhalers, hormone patches, insulin, and EpiPens. Some packaging will give clear storage instructions, but not all medicines come with a visible warning.
Medicines that need to be kept in the fridge - such as insulin or certain liquid antibiotics - are especially vulnerable to heat. If they're left out too long or stored incorrectly, they may not work properly when you take them.
If your medicine has changed colour, developed an unusual smell, changed texture, or looks different in any way, this could signal heat damage. Ask your pharmacist for advice.
If you're at home, check the patient information leaflet for storage instructions and keep medicines in the coolest part of the house, away from direct sunlight. If you're travelling, avoid leaving them in parked vehicles or warm bags. A cool bag can help if you're going to be out all day.
Heat damage can also affect how much medicine your body absorbs, potentially making your usual dose too strong or too weak. If you notice any changes in how you feel or how well your medicines seem to be working during hot weather, speak to your pharmacist or doctor.
Don't forget medical devices:
It's not just medicines - some medical devices can also be affected by heat or humidity. For example, blood glucose monitors may give people managing diabetes less reliable readings if used or stored in hot conditions.
Keep devices and any test strips somewhere cool and dry, and check the instructions that came with them for any temperature guidance. If your device isn't behaving as expected, try running a control check or speak to your pharmacist for advice.
