Cetirizine is a potent and highly selective antagonist of the peripheral histamine H1-receptor on effector cells in the GI tract, blood vessels, and respiratory tract.
It is used in the treatment of allergic conditions (urticaria, rhinitis, conjunctivitis), and is also helpful in the management of morphine-induced pruritus.

Adult, PO: 10 mg once daily or 5 mg bid.

Adverse drug reactions: somnolence, insomnia, fatigue, dizziness, headache, pharyngitis, abdominal pain, coughing, diarrhea, epistaxis, bronchospasm, nausea, vomiting, dry mouth.

Adapted CIMS Drug Information System. Internet. Accessed on January 10, 2016.