Overview

• The UK Health Security Agency and NHS have reinforced guidance for medication users to recognise heat-related risks and seek personalised advice from pharmacists or doctors.
• Heat exposure can degrade insulin and certain antibiotics when stored above 25°C, leading to reduced potency and treatment reliability.
• Diuretics and blood pressure drugs such as ACE inhibitors, beta-blockers and calcium channel blockers increase urination and suppress cooling responses, raising dehydration and heat-illness risks.
• Antidepressants, antipsychotics and stimulant medications impair sweating and elevate core temperature, making it harder for the body to detect and respond to overheating.
• Sun-sensitising treatments, notably methotrexate and some antibiotics, can provoke severe skin reactions—rashes, blistering or burns—even in mild sunshine.