Dangers of older allergy drugs often underestimated and overlooked

A joint report to be published in Allergy reviews new data on the treatment of allergies with older antihistamines compared with newer, second-generation H₁-antihistamines. The research was funded by GA²LEN, an EU-funded Network of Excellence.

The findings suggest that first-generation H₁-antihistamines not only make patients drowsy, but also reduce rapid eye movement (REM) sleep, impair learning, and reduce efficiency at work the next day. In addition, first-generation H₁-antihistamines have been implicated in numerous civil aviation, motor vehicle, and boating accidents, and even deaths as a result of accidental or intentional overdosing in infants and young children. First-generation H₁-antihistamines have also been linked to suicide cases in both teenagers and adults.

New generation antihistamines on the contrary have shown an equivalent efficacy to treat symptoms while clinical studies and patients report fewer adverse effects. The review ultimately questions whether, for consumer protection reasons, first generation H1-antihistamines should still be available as over-the-counter self-medication.

Antihistamines are most frequently used drugs for treating seasonal and chronic allergic diseases such as allergic rhinitis, urticaria, atopic dermatitis. More than 30% of the EU and US population are potential users, safety is thus paramount.