The Met Office has issued yellow and amber heatwave warnings for the third heatwave of 2026, prompting urgent advice for people taking three common medications: sertraline, citalopram, and fluoxetine. These drugs, along with insulin, hormonal contraception, blood pressure medication, SSRIs, ADHD stimulants, inhalers, and EpiPens, can affect how the body responds to high temperatures.
Expert Guidance on Heat and Medication
Jason Murphy, Head of Pharmacy at Chemist4U, highlighted the risks: “With temperatures climbing again this week and heat-health alerts back in place, it’s really important that people on regular medication stop and think about how the heat might be affecting them. The one I’d particularly flag is SSRIs (sertraline, citalopram, fluoxetine and the like), which are among the most widely prescribed medicines in the UK.”
He explained that SSRIs can interfere with the hypothalamus, the part of the brain that regulates body temperature, potentially causing excessive sweating, reduced sweating, dizziness, or dehydration without noticeable thirst.
Storage and Hydration Tips
Most medicines should be stored below 25°C. Cars, sunny windowsills, handbags, and beach bags can become much hotter, degrading active ingredients and rendering medication ineffective. If a medicine changes colour, smell, or texture, consult a pharmacist before use.
People on SSRIs, SNRIs, GLP-1 medications, or ADHD stimulants may not feel thirsty as they should. Murphy advises sipping water regularly, limiting alcohol and caffeine, and for those on diuretics, consulting a GP or pharmacist about fluid intake adjustments during the hot spell.
Recognising Heat Exhaustion and Heat Stroke
Heat exhaustion symptoms include headaches, dizziness, nausea, cramps, heavy sweating, or unusual tiredness or confusion. Move to a cool place, sip water, and cool skin with a damp cloth. If symptoms do not improve within 30 minutes, or if someone becomes confused, stops sweating, or loses consciousness, call 999 immediately—this indicates heat stroke, a medical emergency.
Medications Affected by Heat
Commonly prescribed medications that require caution during the heatwave include: SSRI antidepressants, SNRI antidepressants, tricyclic antidepressants, GLP-1 medications, diuretics, beta-blockers, ACE inhibitors and ARBs, ADHD stimulants, insulin, hormonal contraception, inhalers and EpiPens, and sun-sensitising medicines.
Murphy stressed: “Never stop or change the dose of a prescription medication because of the weather without speaking to a healthcare professional first. Your GP, mental health team, or pharmacist can give you tailored advice. In case of an emergency, it’s usually quicker and easier to get in touch with a pharmacist.”
