Zyrtec (Cetirizine) 5 mg and 10 mg Tablets: OTC Non-Drowsy 24-Hour Antihistamine for Hay Fever, Chronic Urticaria, and Year-Round Allergic Rhinitis — Available Over the Counter Without Prescription

Information last reviewed: May 2026 — for educational purposes only.

Zyrtec is the most prominent brand of cetirizine hydrochloride, a second-generation antihistamine used for the management of seasonal and perennial allergic rhinitis, chronic spontaneous urticaria, and other allergic conditions. Cetirizine is the active metabolite of hydroxyzine and combines reliable 24-hour coverage with a faster onset than loratadine — typically within one hour of ingestion. It is available without a prescription in the United States, Canada, Australia, and most of Europe.

What Is Cetirizine?

Cetirizine is a selective H₁ receptor antagonist classified as a second-generation antihistamine. It is more peripherally selective than hydroxyzine (from which it is derived) but slightly less peripherally selective than loratadine, meaning a small proportion of patients may experience mild sedation — particularly at the 10 mg dose. This mild drowsiness effect is dose-dependent; it is generally not a practical concern at the recommended daily dose for most adults, but individual responses vary.

The drug is excreted largely unchanged in urine, which means dosage adjustments may be needed in patients with significant kidney impairment. Unlike some antihistamines, cetirizine does not undergo significant cytochrome P450 metabolism, resulting in a low risk of drug–drug interactions through that pathway.

Over-the-Counter Availability

Cetirizine became available OTC in the United States in 2007 when regulation transferred it from prescription (Rx) to over-the-counter status. It is sold as Zyrtec and under numerous pharmacy own-label generic names. In the UK it is a Pharmacy (P) medicine. No prescription is required from a doctor to purchase standard cetirizine 10 mg tablets for allergy relief in adults and children over six years old (or over two with appropriate formulation).

Cetirizine is considered one of the most efficacious antihistamines available OTC, particularly for patients whose allergy symptoms have a significant urticaria (hive) component, where it is sometimes preferred over loratadine.

Tablet and Liquid Strengths

Cetirizine products come in several forms and strengths:

• 10 mg tablets — standard adult and adolescent dose (age 12+); once-daily; available as Zyrtec and generic cetirizine
• 5 mg tablets / chewable tablets — for children aged 6–11 and adults who prefer a half-dose (e.g., those sensitive to mild drowsiness)
• 5 mg / 5 ml syrup — for children from age 2; flavoured liquid with calibrated dosing
• Cetirizine dissolving strips — film that dissolves on the tongue, useful without water
• Zyrtec-D (cetirizine + pseudoephedrine) — combination formulation adding a nasal decongestant; kept behind the pharmacy counter due to pseudoephedrine content

Because the drug has a relatively long half-life (approximately eight to ten hours), once-daily dosing provides continuous symptom control for most patients throughout the day and night.

Price and Generic Cetirizine

Generic cetirizine 10 mg tablets are available at very low cost per dose from most supermarkets and pharmacies. A 365-count generic supply can be purchased at a unit cost substantially lower than branded Zyrtec. The FDA considers generic cetirizine therapeutically equivalent to Zyrtec. For patients managing allergies year-round, purchasing large quantities of generic cetirizine represents the most cost-effective approach.

Frequently Asked Questions

Does Zyrtec cause drowsiness?

A small percentage of people experience mild drowsiness with cetirizine at the 10 mg dose. It is significantly less sedating than first-generation antihistamines like diphenhydramine. However, it is marginally more likely to cause drowsiness than loratadine or fexofenadine. Patients who find it sedating can consider switching to fexofenadine (Allegra), which has the lowest sedation profile among common OTC antihistamines.

How quickly does Zyrtec work?

Cetirizine typically provides noticeable symptom relief within one hour. Clinical onset can occur as early as 20 to 30 minutes post-ingestion for some patients. Its effects persist for at least 24 hours, which is why once-daily dosing is appropriate.

Can cetirizine be used for hives?

Yes. Cetirizine is licensed for repeated use in chronic idiopathic urticaria (hives without an identifiable external trigger) and is one of the preferred options in clinical guidelines for this condition. Second-generation antihistamines like cetirizine are favoured over first-generation options for long-term urticaria management because they avoid the sedation and anticholinergic burden of first-generation drugs.

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