Zyrtec (cetirizine hydrochloride) is a leading second-generation antihistamine indicated for the rapid and effective management of allergic rhinitis and chronic urticaria. As a potent H1-receptor antagonist, it provides comprehensive symptomatic relief by selectively inhibiting histamine release, a primary mediator in allergic responses. Its non-sedating profile and 24-hour duration of action make it a first-line therapeutic choice for both seasonal and perennial allergies in adults and children. Supported by extensive clinical evidence, Zyrtec offers a reliable and well-tolerated solution for patients seeking to restore daily comfort and function.

Features

• Active ingredient: Cetirizine hydrochloride 10 mg (tablets) / 5 mg per 5 mL (syrup)
• Second-generation, piperazine-class antihistamine
• Rapid onset of action: begins working within 1 hour post-administration
• 24-hour sustained relief from allergy symptoms with once-daily dosing
• Available in multiple formulations: tablets, chewables, and syrup for pediatric use
• Minimal anticholinergic effects and low potential for sedation compared to first-generation agents
• Excipient-free options available for patients with specific sensitivities

Benefits

• Provides rapid and prolonged relief from sneezing, rhinorrhea, nasal pruritus, and ocular symptoms
• Effectively reduces the severity and frequency of urticaria (hives) and associated pruritus
• Enables improved sleep quality and daytime alertness by minimizing nocturnal allergy disruptions
• Supports uninterrupted daily activities, work, and exercise through consistent symptom control
• Reduces the need for rescue medication and improves overall quality of life during allergy seasons
• Suitable for long-term management with a well-established safety profile

Common use

Zyrtec is commonly prescribed for the management of symptoms associated with seasonal allergic rhinitis (hay fever), including sneezing, runny nose, itchy/watery eyes, and nasal congestion. It is also indicated for perennial allergic rhinitis caused by indoor allergens such as dust mites, pet dander, and mold. Additionally, Zyrtec is effective in the treatment of chronic idiopathic urticaria, providing relief from wheals and pruritus. Off-label uses may include adjunctive therapy in mild allergic asthma and atopic dermatitis, though these should be supervised by a healthcare provider.

Dosage and direction

For adults and children 12 years and older: 10 mg once daily, administered orally with or without food. For children 6 to 11 years: 5 mg or 10 mg once daily, as directed by a physician. For children 2 to 5 years: 2.5 mg once daily; dosage may be increased to a maximum of 5 mg daily (given as 2.5 mg every 12 hours). For pediatric patients under 2 years, use only under medical supervision. Tablets should be swallowed whole with water; chewable tablets must be chewed before swallowing. The syrup formulation should be measured using the provided dosing device. Dosage adjustment may be necessary in patients with renal or hepatic impairment.

Precautions

Patients should avoid driving or operating heavy machinery until their individual response to Zyrtec is determined, as although rare, drowsiness may occur. Use with caution in elderly patients due to potential age-related reductions in renal function. Those with hepatic impairment should receive a reduced dosage. Alcohol and other CNS depressants may potentiate sedative effects. Patients with phenylketonuria should be aware that chewable tablets contain phenylalanine. Discontinue use at least 48 hours before skin allergy testing to avoid false negatives.

Contraindications

Zyrtec is contraindicated in patients with a known hypersensitivity to cetirizine, hydroxyzine, or any component of the formulation. It should not be used in patients with severe renal impairment (CrCl <10 mL/min) unless under direct medical supervision. Use during pregnancy only if clearly needed and after consulting a healthcare provider. Not recommended for children under 2 years of age without professional medical advice.

Possible side effect

Most side effects are mild and transient. Common adverse reactions include somnolence (approximately 11% of adults, 2–4% in children), fatigue, dry mouth (5%), and headache (4–14%). Less frequently reported are dizziness, nausea, abdominal discomfort, and pharyngitis. In rare instances, hypersensitivity reactions such as rash, pruritus, angioedema, and anaphylaxis may occur. Paradoxical CNS stimulation (nervousness, insomnia) has been reported in pediatric patients. Discontinue use and seek medical attention if severe reactions occur.

Drug interaction

Cetirizine has a low potential for pharmacokinetic interactions due to minimal CYP450 metabolism. However, concomitant use with CNS depressants (e.g., benzodiazepines, opioids, alcohol) may enhance sedative effects. No clinically significant interactions have been observed with warfarin, theophylline, azithromycin, or ketoconazole. Use caution with other anticholinergic drugs, though cetirizine has minimal anticholinergic activity. Always inform your healthcare provider of all medications, including OTC products and supplements.

Missed dose

If a dose is missed, it should be taken as soon as remembered. However, if it is near the time of the next scheduled dose, skip the missed dose and resume the regular dosing schedule. Do not double the dose to catch up. Consistent daily administration is recommended for optimal symptom control.

Overdose

Symptoms of overdose may include drowsiness, agitation, restlessness, and tachycardia. In severe cases, CNS depression or stimulation may occur. There is no specific antidote; treatment is supportive and symptomatic. Gastric lavage may be considered if ingestion is recent. Hemodialysis is unlikely to be effective due to cetirizine’s high protein binding and volume of distribution. Contact a poison control center or seek emergency medical attention immediately.

Storage

Store at room temperature (20–25°C or 68–77°F), in a dry place protected from light and moisture. Keep the bottle tightly closed. Do not freeze the syrup formulation. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging.

Disclaimer

This information is intended for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any new medication or changing your treatment plan. Individual responses to medication may vary. Do not disregard professional medical advice based on content provided here.

Reviews

Clinical studies and patient reports consistently highlight Zyrtec’s efficacy in reducing allergy symptoms, with particular praise for its rapid onset and 24-hour duration. Many users report significant improvement in quality of life, especially during high-pollen seasons. Pediatric formulations are frequently noted for their palatability and ease of administration. A minority of users report drowsiness, though most describe it as mild and diminishing with continued use. Overall, Zyrtec maintains a strong reputation among both clinicians and patients for reliability and tolerability in allergy management.