The acute lethal dose of cetirizine in humans is not known. Somnolence was reported in one adult who ingested 150 mg of cetirizine hydrochloride; 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 cetirizine hydrochloride.
In acute Cetirizine overdosage, treatment should include symptomatic and supportive measures, taking into account the possibility of any concomitantly ingested drugs. There is no specific antidote for overdosage of cetirizine. The drug is not effectively removed by dialysis, and therefore, dialysis would not be effective in acute overdosage of cetirizine, unless a drug that is removed by dialysis were ingested about 180 mg of cetirizine hydrochloride.