The NHS has published a comprehensive list of medications that could become harmful during the ongoing heatwave, as temperatures across the UK remain unusually high for May. While stopping medication may not be possible, reducing the dose could be an option—but only after consulting a pharmacist, GP, or nurse.
How Medications Affect Heat Adaptation
Several types of medication can impair the body's ability to cope with heat. Some affect sweat production and hydration, while others increase body temperature, cause drowsiness, or heighten the risk of organ damage through dehydration. This follows advice from the Medicines and Healthcare products Regulatory Agency (MHRA) and Well Pharmacy UK, who urged residents to store medicines properly during hot weather.
Medicines Affecting Sweat Production
Sweating is the body's natural cooling mechanism. The NHS warns that the following can reduce sweat production:
- Beta blockers (e.g., metoprolol, bisoprolol) for heart conditions and high blood pressure.
- Decongestants (e.g., pseudoephedrine) found in cold remedies.
- Anticholinergic medicines, including some allergy medications (diphenhydramine), sleeping pills, urinary incontinence treatments (oxybutynin), and antidepressants (amitriptyline, nortriptyline).
Medicines That Can Cause Dehydration
Dehydration occurs when the body lacks sufficient fluid. Severe dehydration requires urgent medical attention. Medications that increase dehydration risk include:
- Diuretics (e.g., hydrochlorothiazide, furosemide), laxatives, and diabetes drugs like canagliflozin or empagliflozin that increase fluid loss.
- Antidepressants such as fluoxetine and venlafaxine, which can cause excessive sweating.
Medicines That Raise Body Temperature
Some medications hinder the body's temperature regulation, making heatwaves more dangerous:
- Antipsychotics (e.g., olanzapine, quetiapine).
- Stimulants for attention disorders (e.g., methylphenidate).
Medicines That Cause Drowsiness
Drowsiness can impair concentration and reaction time, leading to neglect of cooling and hydration:
- Anti-anxiety and insomnia medications (e.g., benzodiazepines like lorazepam, oxazepam).
- Nerve pain medications (e.g., pregabalin, gabapentin).
- Opioid pain relievers (e.g., morphine, codeine).
Medicines Increasing Organ Damage Risk via Dehydration
Dehydration while taking certain medications can reduce blood flow to organs:
- Anti-inflammatory drugs (e.g., ibuprofen, naproxen).
- Blood thinners (anticoagulants).
- Blood pressure medications.
- Diabetes medications, including metformin.
- Lithium for bipolar disorder.
The NHS emphasizes that patients should not stop or adjust their medication without professional advice. Pharmacists, GPs, and nurses can provide guidance on managing health during extreme heat.
