As temperatures increase, the Medicines and Healthcare products Regulatory Agency (MHRA) is urging residents to protect medicines from heat damage and stay alert to side effects during hot weather.
With Hampshire in the grip of another summer heatwave, the MHRA has issued a reminder to the public about how high temperatures can affect medicines and how they work.
Heat can cause chemical changes in some medicines, reducing their effectiveness and even posing risks to health – particularly for those managing long-term conditions such as diabetes, asthma, or heart disease.
To help people stay safe, the MHRA has shared three key pieces of advice:
1: Store Medicines Somewhere Cool and Dry
Avoid leaving medicines in hot places like cars, bags, or sunny windowsills. Most medicines should be kept below 25°C. Exposure to heat can cause:
- Reduced effectiveness of tablets, insulin, inhalers and EpiPens
- Spoilage of fridge-stored medicines, such as liquid antibiotics
- Unreliable readings from medical devices like glucose monitors
Check packaging and leaflets for storage instructions. Signs of heat damage include unusual smells, changes in texture or discolouration. If you’re unsure, speak to your pharmacist.
2: Stay Hydrated – Especially if You’re on Certain Medications
Some drugs, including diuretics, blood pressure tablets, and diabetes medication, increase the risk of dehydration or affect your body’s ability to regulate temperature. Common signs of dehydration include:
- Dizziness or headaches
- Dark urine
- Fatigue or confusion
Older adults and people with kidney or heart conditions should take extra care to drink water regularly.
3: Be Aware of Sun Sensitivity
Certain medicines can make your skin more likely to burn, even in mild sunshine. These include:
- Some antibiotics, diuretics, and antidepressants
- Skin treatments for eczema or acne
- Methotrexate, used for arthritis, Crohn’s disease and cancer
If your medicine affects sun sensitivity, avoid direct sunlight, wear high-factor sunscreen, and cover up where possible.
Alison Cave, MHRA Chief Safety Officer, said:
“Hot weather can change how your body reacts to medicines – and how well those medicines work. A few simple precautions can make a big difference. Always check the leaflet or speak to your pharmacist if you’re unsure.”
Residents can report issues or side effects using the MHRA’s Yellow Card scheme. For more information on medicine safety, visit: www.gov.uk/mhra.