The UK's Medicines and Healthcare products Regulatory Agency (MHRA) has issued a caution for people taking common medications, including painkillers like ibuprofen and naproxen, as temperatures rise. The guidance highlights a greater risk of heat stroke and other heat-related illnesses, especially for those on certain drugs.
Heat Can Affect Medications and Your Body
According to the MHRA, some medicines can make your skin more prone to sunburn, and others may increase the risk of internal organ damage if you become dehydrated. Anti-inflammatory drugs such as ibuprofen and naproxen are among those that can heighten this risk. Ibuprofen is used to relieve mild to moderate pain, reduce inflammation, and lower fevers, while naproxen works longer to treat conditions like arthritis, gout, and menstrual cramps.
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 diuretics or have a condition like asthma, heart disease, or diabetes.”
Medicines That Increase Risk in Heat
West Yorkshire Health and Care Partnership also issued guidance, stating: "If you become dehydrated and are taking certain medicines, this can decrease blood flow to your internal organs which can potentially cause damage." Medications that may increase this risk include:
- Anti-inflammatory medications such as ibuprofen or naproxen.
- Blood thinners used to prevent clots.
- Medications for high blood pressure.
- Diabetes medications, including metformin.
- Lithium for bipolar disorder.
The MHRA added: "Painkillers such as ibuprofen or naproxen are also known to sometimes cause mild sun sensitivity, but this is less common and usually only a concern with frequent or long-term use."
Recognize Dehydration Symptoms
Dehydration occurs when your body loses more fluids than it takes in. Babies, children, and older adults are more at risk. Symptoms in adults and children include thirst, headache, dark urine, dizziness, dry mouth, and sunken eyes. In babies, signs include a sunken soft spot, few tears, fewer wet nappies, and drowsiness.
If you experience severe symptoms like blue or blotchy skin, difficulty breathing, confusion, or difficulty waking, call 999 or go to A&E.
Storing Medicines Safely
Most medicines should be stored below 25°C. Heat can break down active ingredients, so keep them in a cool, dry place away from direct sunlight. If your medicine changes color, smell, or texture, ask your pharmacist for advice.
