Zyrtec Tablet contains Cetirizine 10mg, a second-generation antihistamine used primarily for the relief of allergy symptoms. Cetirizine selectively inhibits peripheral H1 histamine receptors, thereby reducing the effects of histamine, a substance in the body that causes allergic symptoms. This medication is indicated for the treatment of seasonal allergic rhinitis, perennial allergic rhinitis, and chronic idiopathic urticaria. Zyrtec provides effective relief from symptoms such as sneezing, runny nose, itchy or watery eyes, and itching of the nose or throat. Due to its minimal penetration of the blood-brain barrier, Cetirizine is associated with a lower incidence of sedation compared to first-generation antihistamines. The usual adult dose is 10mg once daily, which can be adjusted based on clinical response and patient tolerance. It is important to use Zyrtec under medical supervision, especially in patients with renal impairment, as dose adjustment may be necessary. Common side effects may include headache, dry mouth, and fatigue, though these are generally mild and transient. Zyrtec should be used with caution in pregnant or breastfeeding women, and patients should avoid concomitant use with other sedating medications unless advised by a healthcare professional.