MHRA warns hot cars and luggage can affect medicines

You can remember the sun cream, double-check the passport and still miss the one thing that matters most on a hot day: where your medicine is sitting. In its summer advice, the Medicines and Healthcare products Regulatory Agency, or MHRA, says many people leave medicines on sunny windowsills, in warm bags or in parked cars without realising that heat can affect how well they work. That is why this is more than a travel tip. Medicine storage is part of medicine safety. If a treatment is meant to help you manage your health, where you keep it matters just as much as remembering to pack it.

The MHRA says many medicines are meant to be stored below 25°C. Some need refrigeration, while others should be kept at room temperature. The important point is not to guess. Check the patient information leaflet or the packaging that came with your medicine, because the correct storage conditions can differ from one product to another. This can be especially important for insulin, certain inhalers, creams for skin conditions and some contraceptives. The same warning also applies to some medical devices, including blood glucose monitors and insulin strips, because hot weather can affect more than tablets and bottles.

The reason for the warning is simple. In summer, places such as parked cars, packed suitcases, caravans and sunny rooms can get much hotter than people expect. According to the MHRA, those conditions may reduce how well some medicines work. **What it means for you:** a medicine bag left in direct sun or a suitcase sitting in a hot car is not just badly placed luggage. It may be storing treatment in conditions it was never meant to handle. The agency's message is really about long periods in heat, even when that heat does not seem dramatic at first glance.

The safest starting point is ordinary but important advice: keep medicines somewhere cool, dry and out of direct sunlight. At home, that usually means avoiding bathrooms, windowsills and shelves near cookers or radiators. When you are travelling, it means thinking ahead rather than leaving medicines in luggage for hours and hoping for the best. There is a useful distinction here. If a leaflet says a medicine needs refrigeration, that instruction still applies in hot weather. If it says room temperature, that does not mean any temperature at all. It means the kind of indoor conditions described in the instructions, not the heat trapped inside a car or a sealed bag on a very warm day.

This is one of those health stories where the best advice is also the easiest to act on. Read the label. Read the leaflet. If you are unsure, ask a pharmacist. The MHRA says pharmacists can help if you are not certain how a medicine should be stored, or if you think it may have been exposed to excessive heat. If you no longer have the leaflet, the MHRA says patient information leaflets are available online through its website. That matters because storage instructions are not extra detail. They are part of using a medicine properly.

If you suspect a medicine is not working as it should, the MHRA says you should speak to a pharmacist or doctor. The agency also asks people to report suspected problems through its Yellow Card scheme, which is used to flag possible safety issues with medicines and medical devices. The wider lesson is worth keeping with you all summer. We often think about medicine safety in terms of dose and timing, but storage matters too. So before a trip, a festival weekend or a hot spell at home, add one more question to your routine: where is your medicine now, and is that place actually safe for it? The MHRA has also published broader summer health advice for people who want to check medicines, medical devices and hot-weather safety in more detail.