Class: Antihistamine (Second-Generation)
Indications
- Allergic Rhinitis (seasonal or perennial)
- Chronic Idiopathic Urticaria (hives)
- Relief of itching, sneezing, and runny nose caused by allergies
- Allergic skin reactions
Mechanism of Action
- Selectively blocks histamine (H1) receptors to prevent and reduce allergic symptoms
- Minimizes histamine’s effects on capillaries, reducing swelling, redness, and irritation
- Less likely to cross the blood-brain barrier, causing fewer sedative effects compared to first-generation antihistamines
Dosage
- Adults and children over 12: 10 mg once daily
- Children 6-12 years: 5-10 mg daily
- Children 2-6 years: 2.5-5 mg daily
- Renal impairment: Adjust dose based on creatinine clearance; typically 5 mg once daily
Forms Available
- Tablets: 10 mg
- Chewable tablets: 5 mg, 10 mg
- Oral solution: 1 mg/mL
- Extended-release capsules (combination products)
Brand Names and Manufacturers
- Zyrtec (Johnson & Johnson)
- Cetirizine Hydrochloride (various generics)
- Alleroff (Perrigo)
- Reactine (Pfizer Canada)
- Histazine (Sanofi)
Cost
- Tablets: $5–$15 for a 30-count bottle (generic)
- Liquid solution: $10–$25 per bottle (varies by size and manufacturer)
Contraindications
- Hypersensitivity to cetirizine, hydroxyzine, or any excipients
- Severe renal impairment (CrCl < 10 mL/min)
Precautions
- Use with caution in patients with moderate to severe renal or hepatic impairment
- May cause mild sedation; avoid operating machinery until effects are known
- Increased sedative effects when combined with alcohol or other CNS depressants
Side Effects
- Common: Drowsiness (less than first-generation antihistamines), dry mouth, fatigue, headache, dizziness, nausea
- Less common but serious: Severe allergic reactions (rash, itching, swelling, difficulty breathing), tachycardia
Drug Interactions
- Alcohol: Enhances sedative effects
- CNS Depressants (e.g., benzodiazepines, opioids): Increased risk of drowsiness
- Theophylline: May reduce cetirizine clearance at high doses
- Ritonavir: Can increase cetirizine levels, possibly enhancing side effects
Monitoring Parameters
- Symptom relief and reduction in allergic reactions
- Assess renal and hepatic function in patients with impairment
- Monitor for excessive sedation or allergic reactions
Patient Counseling Points
- Take once daily, with or without food
- Avoid alcohol to reduce drowsiness risk
- Inform the doctor of other medications to avoid interactions
- If using the liquid solution, use the provided measuring device for accurate dosing
- Do not exceed recommended dose to prevent side effects
- Store at room temperature, away from moisture and light
FAQs About Cetirizine
Q1: How long does cetirizine take to work?
- Starts relieving symptoms within 1 hour; full effect in 2-3 hours
Q2: Can cetirizine be taken daily? - Yes, safe for daily use in managing chronic allergies or urticaria
Q3: Is cetirizine safe for children? - Yes, approved for children aged 2 years and older, with proper dosing adjustments
Q4: Does cetirizine cause drowsiness? - Mild drowsiness is possible but less common than with older antihistamines
Q5: Can I take cetirizine during pregnancy? - Generally considered safe but consult your doctor before use
Q6: Is cetirizine effective for food allergies? - Not a treatment for acute food allergy reactions; consult a doctor for severe allergic responses
Q7: What should I do if I miss a dose? - Take as soon as you remember unless it’s close to the next dose; do not double doses
Cetirizine Monograph
Brand Name: Zyrtec
Class: Second-Generation Antihistamine
Indication: Allergic rhinitis, urticaria, allergic skin reactions
Mechanism of Action: Blocks H1 receptors to alleviate allergic symptoms
Dosage: 10 mg daily for adults, adjusted for age and renal function
Contraindications: Severe renal impairment, hypersensitivity to ingredients
Precautions: Use caution in renal/hepatic impairment; avoid alcohol
Side Effects: Drowsiness, dry mouth, fatigue, headache, dizziness
Drug Interactions: Alcohol, CNS depressants, theophylline, ritonavir
Monitoring: Symptom control, renal and hepatic function in impaired patients
Patient Counseling: Take as directed, avoid alcohol, use proper measuring devices for liquid form
Use in Pregnancy: Generally safe; consult doctor
Use in Kidney Disease: Adjust dose; monitor function
Use in Liver Disease: Use with caution; consult doctor
Use in Elderly: Monitor for increased sensitivity to side effects
