Second-generation antihistamines: a study of poisoning in children

Background and objectives: The toxicity of second-generation antihistamines after an overdose by a child is still unknown. The objective of this study is to use data from Poisons Centres in France to describe the toxicity profile of second-generation antihistamines for children and to compare the severity of poisoning observed from these with a first-generation antihistamine.Method: This was a retrospective, multi-centre and observational study focusing on human cases of single-substance exposure to a second-generation antihistamine and to mequitazine, reported between 1 January 2001 and 31 December 2016 in Poisons Centres in France.Results: From a total of 9403 children included, 5980 were exposed to a second-generation antihistamine and 3423 were exposed to mequitazine. The severity of exposure to second-generation antihistamines in children is low: among the children followed until a known outcome, 9% of children were symptomatic and in 97% of cases, the symptoms shown were of a minor-level severity (primarily drowsiness or restlessness). Depending on the substance, children who ingested doses 16 to 69 times the maximum recommended therapeutic dose remained asymptomatic. No deaths or severe symptoms were observed. No cases of lengthening of the QT interval or arrhythmias were identified. Mequitazine led to more symptoms than other substances (14.8% symptomatic children vs. 7.5%, Odd ratio (OR): 2.3 (2.0-2.6), p < 0.0001), more symptoms of moderate intensity (1.4 vs. 0.2%, OR: 8.3 (4.1-18.5), p < 0.0001) and more hospitalisation (19.1 vs. 8.7%, OR: 2.5, 95% CI: (2.2-2.8), p < 0.0001).Conclusion: The severity of poisoning from second-generation antihistamines appears to be low among children and considerably lower than poisoning caused by mequitazine.