What is the dosage and usage of Cetirizine (antihistamine) for treating allergic conditions?

From the Guidelines

Cetirizine is typically taken at a dose of 10 mg once daily for adults and children 6 years and older for treating allergic conditions such as seasonal allergies, hay fever, and hives. For children 2-5 years old, the recommended dose is 2.5 mg (half a teaspoon of syrup) once or twice daily, not exceeding 5 mg daily. Children 6-11 years may take 5-10 mg once daily. Elderly patients and those with kidney impairment should start with 5 mg daily. Cetirizine works by blocking histamine receptors, reducing allergy symptoms like sneezing, itching, watery eyes, and runny nose. It's best taken at the same time each day, with or without food. Unlike older antihistamines, cetirizine causes less drowsiness, though some patients may still experience this side effect, as seen in studies where 13.7% of patients age 12 years experienced mild drowsiness compared with 6.3% for placebo 1. The medication typically begins working within an hour and lasts for 24 hours. For seasonal allergies, starting cetirizine before allergen exposure can provide better symptom control. Some key points to consider when using cetirizine include:

• The efficacy and safety of antihistamines in urticaria is undisputed, although not all patients respond and some may become worse 1.
• Cetirizine has the shortest time to attain maximum concentration, which may be an advantage where rapid availability is clinically important 1.
• Patients should consult their healthcare provider before use if they have other medical conditions or take other medications. It is also worth noting that cetirizine may be sedating, especially at higher doses, and patients with low body mass may conceivably reach an elevated dosage level and develop drowsiness and/or performance impairment 1.

From the FDA Drug Label

PRINCIPAL DISPLAY PANEL-500'S COUNT Rising® 16571-402-50 Original Prescription Strength Cetirizine Hydrochloride Tablets USP 10 mg 6 yrs & older Antihistamine ALLERGY Indoor & Outdoor Allergies 24 Hour Relief of: •Sneezing •Runny Nose •Itchy, Watery Eyes •Itchy Throat or Nose Active Ingredient (in each tablet) Cetirizine HCl USP 10 mg

• Cetirizine is an antihistamine used for the treatment of allergic conditions, including:
  • Sneezing
  • Runny Nose
  • Itchy, Watery Eyes
  • Itchy Throat or Nose
• The dosage is 10 mg per tablet, for individuals 6 years and older.
• It provides 24-hour relief for indoor and outdoor allergies 2 2

From the Research

Cetirizine Overview

• Cetirizine is an antihistamine used to treat allergic conditions such as chronic idiopathic urticaria [(3,4)].
• The recommended dosage of cetirizine is 10mg, administered over a period of 5 days 3.

Dosage and Usage

• The study compared the effect of cetirizine 10mg, desloratadine 5mg, fexofenadine 120 and 180mg, levocetirizine 5mg, loratadine 10mg, and placebo on histamine-induced skin reaction 3.
• Cetirizine was found to significantly reduce histamine-induced wheal, flare, and LDF index, with the maximum effect observed within the first 24 hours 3.
• In the treatment of chronic idiopathic urticaria, cetirizine was found to have a therapeutic advantage over fexofenadine, with 51.9% of patients becoming symptom-free compared to 4.4% with fexofenadine 4.

Side Effects and Contraindications

• Cetirizine can cause uncommon adverse reactions, including urticaria, as reported in a case study where a patient experienced exacerbations after treatment with cetirizine 5.
• The study highlights the importance of identifying uncommon adverse reactions to H1 antihistamines, as they may mimic the underlying disease 5.