Overdosage has been reported in individuals receiving cetirizine hydrochloride. Somnolence was reported in the adult who ingested 150 mg of drug; no other adverse effects, including clinical manifestations, abnormal blood chemistry, or abnormal hematology occurred in this individual. Restlessness and irritability followed by drowsiness were reported in an 18-month old child who ingested about 180 mg of drug. In acute overdosage, treatment should include symptomatic and supportive measures, taking into account the possibility of any concomitantly ingested drugs.