As UK temperatures approach 35°C, health experts are warning that popular hay fever medications such as Benadryl, Clarityn and Piriteze may pose additional risks during extreme heat. The NHS cautions that antihistamines can cause drowsiness, dry mouth and dizziness, side effects that become more significant when the body is already struggling to regulate temperature in scorching conditions.
How Antihistamines Affect Heat Regulation
Reduced alertness and dry mouth can indirectly increase the risk of dehydration, particularly if people are not drinking enough fluids during hot spells. This concern grows as temperatures edge towards heatwave levels across large parts of the UK. Certain antihistamines, especially older sedating types, also carry mild anticholinergic properties that can restrict sweating in some individuals, potentially undermining the body's natural cooling mechanism and increasing susceptibility to overheating.
Official Guidance and Vulnerable Groups
The Medicines and Healthcare products Regulatory Agency has previously warned that sedating medications should be used with care in situations involving heat exposure, physical exertion or activities requiring full alertness. This guidance is especially crucial for older adults and those with underlying health conditions. The UK Health Security Agency issues heat-health alerts when temperatures pose risks to vulnerable groups, including elderly people, those with long-term illness and individuals taking certain medications. Its advice focuses on staying hydrated, avoiding sun exposure during the hottest parts of the day and keeping living spaces cool.
Sedating vs Non-Drowsy Antihistamines
Pharmacists regularly draw a distinction between older sedating antihistamines, such as chlorphenamine, and newer 'non-drowsy' alternatives like cetirizine or loratadine. While the newer generation is less likely to cause drowsiness, experts note that dryness, fatigue or mild heat sensitivity may still occur in some cases. General public health advice during heatwaves includes drinking water regularly even without feeling thirsty, steering clear of alcoholic drinks, wearing light clothing and seeking shade or cooler indoor spaces during the hottest periods of the day.
Alternatives and Precautionary Measures
For hay fever sufferers, saline sprays or steroid nasal treatments could be worth exploring as alternatives after speaking with a pharmacist or GP. As heatwaves become increasingly frequent across the UK, the connection between seasonal allergies and soaring temperatures is attracting heightened attention. What would normally be a routine daily tablet could assume greater importance when the body is under heat-induced stress.
