The sedating antihistamines include brompheniramine, chlorpheniramine, cyproheptadine, dexchlorpheniramine, dimenhydrinate, diphenhydramine, doxylamine, pheniramine and promethazine

The non-sedating antihistamines include cetirizine, desloratadine, fexofenadine, levocetirizine and loratadine. In overdose they cause mild CNS depression, in therapeutic and supra therapeutic doses they have been associated with QT prolongation.