The Medicines and Healthcare products Regulatory Agency (MHRA) has issued a stark warning to drivers and holidaymakers: medicines must not be left in hot environments such as cars, suitcases, or caravans this summer. As temperatures soar and the holiday season peaks, the agency emphasizes that many medications lose their potency or become unsafe when exposed to excessive heat.
Why Heat Damages Medicines
Most medicines are designed to be stored below 25°C. When temperatures rise above this threshold, chemical compounds can break down, rendering drugs less effective or even potentially harmful. The MHRA notes that this is particularly critical for medicines like insulin, certain inhalers, creams for skin conditions, and some contraceptives. Dr Alison Cave, MHRA Chief Safety Officer, explained: “During the summer, places such as parked cars, packed suitcases, caravans, and sunny rooms can get far hotter than people expect. For some medicines, these conditions can affect how well they work.”
Which Medicines Are Most at Risk?
Patients using insulin for diabetes are especially vulnerable, as heat-damaged insulin may not control blood sugar levels effectively, leading to dangerous hyperglycemia. Similarly, inhalers for asthma or COPD can malfunction if exposed to high temperatures, delivering incorrect doses. Skin creams and contraceptive patches may also degrade, losing their therapeutic properties. The MHRA advises checking the patient information leaflet or packaging for specific storage instructions, which are also available online via the MHRA website.
Storage Tips for Summer
To ensure medicines remain safe and effective, the MHRA recommends storing them at home in a cool, dry place away from direct sunlight. Bathrooms and areas near stoves or radiators should be avoided due to humidity and heat. When traveling, never leave medicines in a parked car, even for a short time, as interior temperatures can exceed 50°C. Instead, keep them in a shaded bag or cooler, but avoid direct contact with ice packs if refrigeration is not required. “Checking the storage instructions that come with your medicine, and storing it correctly only takes a few minutes but can help ensure it remains safe and effective when you need it,” added Dr Cave.
What to Do if Medicine Is Affected
If you suspect your medicine has been exposed to excessive heat—for example, if it looks discolored, has an unusual texture, or has expired—do not use it. Speak to a pharmacist immediately for guidance. The MHRA also encourages patients to report any suspected issues with medicine effectiveness through its Yellow Card scheme, which helps monitor drug safety. Pharmacists can also provide advice on proper storage and whether a replacement prescription is needed.
The MHRA’s warning serves as a timely reminder for all drivers and travelers to prioritize medication safety during hot weather. A few simple steps can prevent serious health risks and ensure that essential treatments work as intended.
