Carbinoxamine is a first generation antihistamine that competes with free histamine for binding at HA-receptor sites. This antagonizes the effects of histamine on HA-receptors, leading to a reduction of the negative symptoms brought on by histamine HA-receptor binding. The product label for carbinoxamine as an over the counter cough and cold medicine is being modified to state "do not use" in children under 4 years of age in order to prevent and reduce misuse, as many unapproved carbinoxamine-containing preparations contained inappropriate labeling, which promoted unapproved uses (including management of congestion, cough, the common cold, and the use in children under 2 years of age), which can potentially cause serious health risks.   From: DrugBank