Dosing regimen for injectable cetirizine

1. A method of administering injectable cetirizine or levocetirizine to a human subject, comprising intravenously injecting the human subject subject in need thereof with an intentional or an unintentional overdose of a maximum daily dose of the cetirizine or levocetirizine,

wherein the human subject is a child 6 months to 5 years and the maximum human daily clinical dose of cetirizine dihydrochloride is 2.5 mg; the human subject is a child 6 to 11 years and the maximum human daily clinical dose of cetirizine dihydrochloride is 5 to 10 mg; or the human subject is an adult of adolescent 12 years older and the maximum daily clinical dose of cetirizine dihydrochloride is 10 mg.

2. The method of claim 1 , wherein the human subject is suffering from acute urticaria.

3. The method of claim 2 , wherein the human subject has concomitant angioedema.

4. The method of claim 1 , wherein the injectable composition is a 10 mg/mL aqueous cetirizine dihydrochloride solution.

5. The method of claim 1 , wherein the administering occurs in an emergency department or in an urgent care center.

6. The method of claim 1 , wherein the overdose is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 times the maximum recommended daily clinical dose for the mammal.

7. The method of claim 1 , wherein the overdose is an overdose administered, prescribed by, or suggested by a physician or health care worker.

8. The method of claim 1 , wherein the maximum daily dose of the cetirizine or levocetirizine provides a highest no observable adverse effect level of the cetirizine or levocetirizine.

9. The method of claim 1 , wherein the human subject is not responding to the maximum daily dose.