Background: Children frequently experience harmful whealing and delayed papules from mosquito bites. Whealing is mediated by antisaliva IgE antibodies and histamine, but the effect of antihistamines on mosquito-bite symptoms has not been evaluated in children.
Methods: The effect of loratadine (0.3 mg/kg) was examined in 28 mosquito-bite-sensitive children (aged 2-11 years). The double-blind, placebo-controlled, crossover study was performed with exposure to Aedes aegypti laboratory mosquitoes. The size of the bite lesion and the intensity of pruritus (visual analog scale) were measured at 15 min and at 2, 6, and 24 h.
Results: Loratadine decreased the size of the wheals by 45% (P < 0.001, 25 children) and accompanying pruritus by 78% (P = 0.011, 12 children) at 15 min compared to placebo. The size of the 24-h delayed bite lesion also decreased significantly (P = 0.004), but there was no change at 2 or 6 h. Loratadine was well tolerated and no marked side-effects were recorded.
Conclusions: This study in children shows that prophylactically given loratadine decreases significantly the whealing and pruritus caused by mosquito bites and also reduces the size of the 24-h bite lesions. Therefore, the therapeutic profile of loratadine extends from immediate to delayed allergic symptoms in mosquito-bite-sensitive children.