The effects of antihistamine on the duration of the febrile seizure: A single center study with a systematic review and meta-analysis.

Background: Several studies have investigated the potential effects of antihistamines on febrile seizure. However, these findings are inconsistent across the studies.

Method: A retrospective observational study was conducted on a total of 434 consecutive patients aged between 6 months and 5 years with the diagnosis of febrile seizure. Patients with chronic medical conditions were excluded. Multivariable generalized linear models were conducted to ascertain the effects of antihistamine use on duration of febrile seizure. Also, we conducted a systematic review and meta-analyses of the medical literatures to calculate the pooled estimates using random effects models.

Results: The adjusted mean duration of febrile seizure in the antihistamine group was 4.9 min shorter than that in the non-user group (95% confidence interval (CI), 0.4-9.5). The risk of duration in febrile seizure >5 min among antihistamine users was also 0.83 times that among the non-users (95%CI, 0.58-1.19), whereas the risk of duration in febrile seizure >10 min among first-generation antihistamine users was 1.21 times that among non-users (95%CI, 0.69-2.13). According to the systematic review of the literature, 8 observational studies were included in the meta-analyses. Comparing to non-users, the antihistamine users had prolonged duration of febrile seizure by 1.07 min (95%CI, -1.13 to 3.27), elevated risk of duration in febrile seizure >5 min (Risk ratio, 1.16; 95%CI, 0.90-1.49), and similar duration from fever to febrile seizure onset (pooled mean difference, -0.01 h; -1.43 to 1.41), but these estimates were imprecise. Similar results were obtained when we stratified the data by types of antihistamine (first vs. second generation).

Conclusions: Our study may indicate the effects of antihistamine on prolonging febrile seizure duration, but they are still controversial given the limited evidence, highly heterogeneous results, and concerns of the internal and external validities.