Overview
- The UK Health Security Agency extended amber heat‑health alerts across large parts of England, with warnings remaining in force until Thursday, May 28 and signs that hotter weather will keep pressure on health and social care services.
- The Medicines and Healthcare products Regulatory Agency has issued guidance circulated this week that heat can chemically degrade many medicines and make temperature‑sensitive products less effective when stored in hot cars, bags or on sunny windowsills.
- Certain products are especially vulnerable: refrigerated medicines such as insulin and some liquid antibiotics must stay cold, and devices including inhalers, EpiPens and glucose test strips can malfunction or give unreliable results after heat exposure.
- Some common drug classes can worsen heat harms by altering temperature control or fluid balance — for example, warm conditions speed insulin absorption and raise hypoglycaemia risk, diuretics increase dehydration risk, and methotrexate and some antibiotics can cause severe sun sensitivity.
- Officials and clinicians advise practical steps to reduce harm: keep medicines in the coolest part of the home or use insulated bags when travelling, follow leaflet storage instructions, check products for changed colour or smell, stay hydrated, and contact a pharmacist or GP if you are concerned.