I kontrollerede kliniske undersøgelser, hos voksne og unge var der ingen overhyppighed af døsighed sammenlignet med placebo ved den anbefalede dosis på 5 mg daglig.
In a clinical pharmacology trial, in adults and adolescents, in which desloratadine was administered to adults at a dose of 45 mg daily (nine times the clinical dose) for ten days, no prolongation of QTc interval was seen.