what is Cetirizine ?
Cetirizine is a commonly used antihistamine that helps relieve symptoms of allergies such as sneezing, runny nose, itchy or watery eyes, and itching of the throat or nose. It is also effective in treating skin allergies like hives (urticaria) and itching. Cetirizine works by blocking the action of histamine, a natural substance in the body that causes allergic symptoms during an allergic reaction. By preventing histamine from binding to its receptors, it helps reduce allergy symptoms without completely stopping the body’s normal allergic defense response.
Uses / Indications
Allergic Rhinitis (Hay Fever):
Cetirizine is widely used to relieve symptoms of seasonal or perennial allergic rhinitis, such as sneezing, runny or itchy nose, nasal congestion, and watery eyes caused by pollen, dust, or pet dander.Urticaria (Hives):
It helps reduce itching, redness, and swelling caused by chronic idiopathic urticaria and other allergic skin reactions.Skin Allergies:
Cetirizine provides relief from itchy or irritated skin due to allergic reactions, insect bites, or contact dermatitis.Allergic Conjunctivitis:
It can help relieve itching and redness of the eyes caused by allergic reactions.Common Cold or Flu-Related Allergies (Symptomatic Relief):
Though not a cure for colds, cetirizine may ease runny nose and sneezing triggered by allergens during a cold.Eczema and Atopic Dermatitis (Adjunct Use):
Sometimes prescribed to reduce itching and improve sleep quality in patients with chronic skin conditions.
Dosage
Adults and Children above 12 years:Recommended dose: 10 mg once daily (usually one tablet per day).Can be taken with or without food.Best taken in the evening if it causes mild drowsiness.2. Children (6–12 years):Typical dose: 5–10 mg once daily (depending on symptom severity).Syrup form is often preferred for easier dosing.3. Children (2–6 years):Recommended dose: 2.5–5 mg once daily.Use syrup or oral drops for accurate measurement.4. Infants (6 months–2 years):Dose: 2.5 mg once daily (only under medical supervision).5. Elderly patients / Kidney impairment:Dose may be reduced to 5 mg once daily since the drug is excreted through the kidneys and may accumulate in such conditions.
Mechanism of Action
Cetirizine is a second-generation antihistamine that works by selectively blocking histamine H₁ receptors in the body. Histamine is a natural chemical released by mast cells during an allergic reaction. When histamine binds to its receptors, it triggers common allergy symptoms such as sneezing, itching, runny nose, watery eyes, and swelling.Cetirizine acts by competitively inhibiting histamine binding to the H₁ receptors on the surface of target cells in the respiratory tract, skin, and blood vessels. By blocking these receptors, Cetirizine prevents histamine from exerting its effects, thereby reducing or eliminating allergic symptoms.