The NHS has issued a warning for people taking certain antihistamines this summer, particularly those that cause drowsiness. Antihistamines are commonly used for hay fever, hives, allergic conjunctivitis, and insect bite or sting reactions. The health service divides them into two main groups: those that can make you sleepy and non-drowsy types.
Which antihistamines cause drowsiness?
The NHS lists chlorphenamine (Piriton), cinnarizine, diphenhydramine, hydroxyzine, and promethazine as sedating antihistamines. Non-drowsy options include acrivastine, cetirizine, fexofenadine, and loratadine. The NHS advises that non-drowsy antihistamines are generally the best choice, but sedating ones may help if allergies disrupt sleep.
Key warnings for drowsy antihistamines
For chlorphenamine, the NHS states: "Do not drive a car or ride a bike if it makes you sleepy or dizzy or you get blurred vision." It also warns against consuming alcohol, which can increase drowsiness and nausea. Similarly, diphenhydramine is described as a sedating antihistamine with common side effects including sleepiness, dizziness, unsteadiness, difficulty concentrating, and dry mouth. The NHS advises: "Do not drive or ride a bike if it makes you feel sleepy or dizzy. Do not drink alcohol while taking diphenhydramine. Alcohol increases the risk of side effects."
Choosing the right antihistamine
Antihistamines come in tablets, capsules, liquids, syrups, creams, lotions, gels, eyedrops, and nasal sprays. The NHS notes there is little evidence that any one works better than others; individual responses vary. A pharmacist can help select the most suitable option. Always consult a doctor if concerned about side effects.
