Read up on guidance when taking medication in hot weather (Image: Catherine Falls Commercial via Getty Images)
With vast parts of the UK currently enjoying temperatures soaring above 30C, the Medicines and Healthcare products Regulatory Agency (MHRA) has issued crucial guidance for those taking antibiotics, diuretics or antidepressants.
Hot weather alters the way your body reacts to medication, which could affect people managing long-term conditions – though a handful of straightforward measures can help prevent complications. “Let’s face it – when there’s a heatwave, most of us are focused on getting outside and enjoying it while it lasts,” said the MHRA’s Chief Safety Officer, Alison Cave.
“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.” Indeed, certain widely-used medicines can significantly increase your skin’s susceptibility to burning, even in moderate sunshine.
These include some antibiotics, diuretics, antidepressants, or topical treatments for acne or eczema. Painkillers such as ibuprofen or naproxen are also known to occasionally trigger mild sun sensitivity, though this is less frequent and typically only a concern with regular or prolonged use.
One medication that demands particular attention is methotrexate, prescribed for conditions including rheumatoid arthritis, psoriasis, Crohn’s disease and cancer. It can cause extreme skin sensitivity to the sun – even at low doses. This can lead to painful rashes, blistering, or swelling that looks like severe sunburn. In rare cases, these reactions have led to serious infections.
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The risk goes up during sunny weather, especially if you’re outside more – whether you’re walking the dog, gardening, or heading off on holiday. Even a short walk at lunchtime or a train ride in the sun can be enough to trigger a reaction for some people.
If you are taking any medication, always read the patient information leaflet or consult your pharmacist to establish whether sun sensitivity is listed as a side effect.
On TikTok, Well Pharmacy UK echoes the MHRA’s guidance, noting: “Hot weather can affect both you and your medication.”
It adds: “During the hot weather, remember to:
- Check medicine storage instructions
- Keep medication out of direct sunlight
- Stay hydrated
- Protect your skin with SPF, shade & light clothing.”
Alison summarised: “To stay safe in the heat:
- Store medicines somewhere cool, dry and out of direct sunlight – especially if you’re out and about
- Know the signs of heat-related illness – stay hydrated and listen to your body
- Take extra care in the sun if your medicine makes your skin more likely to burn
“And remember, for all medicines it’s important to read the leaflet and speak to a healthcare professional if you have any questions.”
Medical devices should not be overlooked either, as extreme heat may also have a detrimental impact on them. The MHRA warns: “It’s not just medicines – some medical devices can also be affected by heat or humidity. For example, blood glucose monitors may give people managing diabetes less reliable readings if used or stored in hot conditions.
“Keep devices and any test strips somewhere cool and dry, and check the instructions that came with them for any temperature guidance. If your device isn’t behaving as expected, try running a control check or speak to your pharmacist for advice.”
