Optimal Doses of H1 Antihistamines Do Not Increase Susceptibility to Febrile Convulsions in Children.

<bold>Background: </bold>The purpose of this study was to elucidate whether H1 antihistamine administration increases susceptibility to febrile convulsions in children.<bold>Methods: </bold>A single-center, retrospective observational study was conducted in Japan. The study included 380 children with febrile convulsions between the ages of six months and five years transported via ambulance from 2011 through 2016. They were divided into the preseizure H1 antagonist "use group" and the "nonuse group." The former consisted of children who took H1 antagonists within 24 hours before the seizure onset. The primary outcome (seizure duration) and the secondary outcome (interval from fever to seizure onset) were compared between the two groups.<bold>Results: </bold>Of the 380 study patients, 70 (18%) were identified as the use group. None of the patients was taking excessive doses of H1 antagonists. The prevalence of seizures lasting 15 minutes or longer was not different between the use group and the nonuse group (11% versus 8%, prevalence ratio 1.47 [95% confidence interval, 0.63 to 3.42], P = 0.37). The prevalence of fever to seizure onset less than six hours was significantly lower in the use group (26% versus 52%, prevalence ratio 0.33 [95% confidence interval 0.19 to 0.60], P < 0.001). Similar results were obtained when analyses were conducted separately by different generations (first and second) of H1 antagonists.<bold>Conclusions: </bold>Prolonged seizure duration and shortened interval from fever to seizure were not observed in children who received H1 antagonists. This study provides evidence that H1 antagonists at optimal doses could be safely used in febrile children with allergic symptoms. [ABSTRACT FROM AUTHOR]