People with allergies in the UK are being advised to take extra precautions as temperatures continue to soar, particularly those who carry EpiPens. The warning comes amid concerns that hot weather can affect medication.
EpiPens and hot weather
The Medicines and Healthcare products Regulatory Agency (MHRA) issued a warning in June 2026 urging people to keep medicines, including EpiPens, out of hot cars and direct sunlight. The MHRA stressed that heat can break down active ingredients, meaning medicines might not work when needed. This includes tablets, inhalers, hormone patches, insulin, and EpiPens. Some packaging gives clear storage instructions, but not all medicines come with a visible warning.
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.” She also noted that some medicines can make people more likely to burn in the sun, feel dizzy, or get dehydrated, especially those taking diuretics or with conditions like asthma, heart disease, or diabetes.
Symptoms of anaphylaxis
EpiPen experts stress that severe allergic reactions can occur in response to food, insect stings, medication, latex, exercise, and other allergens. Symptoms of anaphylaxis include: persistent cough, hoarse voice, difficulty swallowing, swollen tongue (airway); difficult or noisy breathing, wheeze or persistent cough (breathing); persistent dizziness, pale or floppy, suddenly sleepy, collapse or unconsciousness (circulation).
Common causes of anaphylaxis include foods such as peanuts, tree nuts, milk, eggs, shellfish, fish, sesame seeds, and kiwi fruit. Non-food causes include wasp stings, bee stings, natural latex, and certain drugs such as penicillin. In some people, exercise can trigger a severe reaction, either alone or in combination with other factors.
Hot weather and medication
The MHRA advises that most medicines need to be stored below 25°C. Cars, trains, buses, and even bags can heat up quickly in summer, potentially causing problems for medicines left out all day. Medicines requiring refrigeration, such as insulin or certain liquid antibiotics, are especially vulnerable. If they are left out too long or stored incorrectly, they may not work properly.
If a medicine changes colour, smell, texture, or appearance, it could signal heat damage. People should ask their pharmacist for advice. At home, check the patient information leaflet and keep medicines in the coolest part of the house, away from direct sunlight. When travelling, avoid leaving them in parked vehicles or warm bags; a cool bag can help. Heat damage can also affect how much medicine the body absorbs, potentially making the usual dose too strong or too weak. If any changes are noticed, speak to a pharmacist or doctor.
