Attention deficit hyperactivity disorder (ADHD) has gained importance lately, because it has become common and has caused serious implication to those affected. DSM-IV-TR defined ADHD by symptoms of inattention, hyperactivity and impulsivity (1). Studies estimated that 4% to 8% of children worldwide have ADHD, which is more prevalent in boys than girls by three folds (2). In Egypt, the prevalence raised to 9.4%(3). There are many speculations about the possible relationship between ADHD and allergy, owing to the fact that ADHD children had allergic disorders. It is putative that ADHD might be a complication of allergy, as it was found that allergic reactions led to a sequence of imbalanced cholinergic/adrenergic activity in the central nervous system (4). On the other hand, ADHD can occur secondary to side effects of antiallergic drugs (5). The pathogenesis of allergy and ADHD both rely on gene-environment interaction, which is complex in nature (6).

Surprisingly, ADHD and allergy share the hypersensitivity phenomenon. When exposed to certain stimuli which are tolerated by normal subjects, a sequence of symptoms occur. As inhalants like mite or ingestants like milk can trigger an allergic reaction, certain foods and pollens can activate ADHD symptoms (7).