The May bank holiday weekend shattered multiple records, becoming the hottest bank holiday on record, the hottest May Day in the UK, and marking the first time temperatures hit 30C this year. It was also the first time such temperatures were recorded in May anywhere in the UK since 2012.
While many welcome the sunny weather as the start of summer, few realise how it can affect their health, particularly their medication. Certain drugs can disrupt the body's ability to handle heat, making individuals more susceptible to dehydration and other heat-related issues. In some cases, extreme heat can also interfere with how the body absorbs and uses medication.
The Medicines and Healthcare products Regulatory Agency (MHRA) has issued an alert highlighting medications that may be affected and reminding people how to avoid weather-related health problems while managing long-term conditions.
Methotrexate
This medication is commonly used for rheumatoid arthritis, psoriasis, Crohn's disease, and cancer. However, it makes the skin extremely sensitive to the sun, even at low doses, causing painful rashes, blistering, or swelling resembling severe sunburn. The MHRA noted: "In rare cases, these reactions have led to serious infections... Even a short walk at lunchtime or a train ride in the sun can be enough to trigger a reaction for some people." Other medications, including some antibiotics, diuretics, antidepressants, and skin treatments for acne or eczema, can also increase sun sensitivity.
Diuretics
Diuretics, or 'water tablets' like furosemide, are prescribed for heart conditions to remove excess fluid and control blood pressure. However, they directly increase the risk of dehydration and mineral imbalances during a heatwave. Important symptoms of dehydration include:
- Feeling thirsty
- Headache and feeling light-headed
- Dark yellow, strong-smelling urine
- Peeing less often than usual
- Feeling dizzy or lightheaded
- Feeling tired
- A dry mouth, lips, and tongue
- Sunken eyes
Blood Pressure Medication
ACE inhibitors, beta-blockers, calcium channel blockers, and other blood pressure medications can make it harder for the body to regulate temperature or suppress the natural thirst response, increasing the risk of dehydration.
Diabetes Medications
Insulin, metformin, and other diabetes drugs can increase the risk of dehydration while making early symptoms harder to spot. Insulin may be absorbed more quickly from injection sites in warm weather, raising the risk of hypos, according to Diabetes UK.
Antipsychotic Medication
Drugs like olanzapine or quetiapine, as well as stimulant medications for attention disorders, can sometimes increase body temperature, meaning individuals may overheat more easily when temperatures climb.
The MHRA urges anyone on medication to read the patient information leaflet or consult their pharmacist to check if they may be at risk of sun sensitivity or other heat-related side effects.
