Attention-deficit/hyperactivity disorder (ADHD) and atopic dermatitis (AD) are two highly prevalent diseases in childhood. Many systemic H1-antihistamines (AH), especially 1st-generation agents (AH1) with significant sedating potential, are frequently used to treat AD-related pruritus and AD-related sleeping problems in infants.

There is, however, no recommendation for systemic treatment with AH within the first year of life. In a small retrospective study of children with AD, we recently observed a significant association of history of antihistamine use and increased risk of ADHD symptoms.?

The objective of the present study was to analyze whether AH exposure within the first 2 years of life represents an independent risk factor for the development of ADHD in children with AD. Moreover, we aimed to investigate whether children, who are exposed to AH, but who do not have AD, have an increased risk for ADHD diagnosis later in childhood.