Cetirizine (Zyrtec): Uses, Warnings, and Key Facts

What is cetirizine?

Cetirizine is a medicine used to treat rhinitis and urticaria. The active ingredient is cetirizine hydrochloride.

In the United States, cetirizine is sold under brand names including Zyrtec, Aller-Tec, Equate Allergy Relief, and All Day Allergy.

How cetirizine works

Cetirizine is a selective H1 antagonist. In simple terms, it helps block part of the allergic response. The source content notes that it inhibits the initial phase of the allergic reaction and reduces the migration of inflammatory cells and the release of mediators linked to the late response.

What cetirizine is used for

Cetirizine is used to relieve symptoms of:

• Seasonal allergic rhinitis
• Perennial allergic rhinitis
• Idiopathic chronic urticaria

The source content states that it is used in adults and children over 2 years for these indications.

How it is taken

The source content describes oral use. Oral drops in solution can be taken as they are or diluted in water. If diluted, they should be taken immediately.

Dosage information from the source

The following dosing information appears in the original content. It should be checked against the official leaflet or a healthcare professional’s instructions before use.

Contraindications listed in the source

The original content lists the following contraindications:

• Hypersensitivity to cetirizine
• Hypersensitivity to hydroxyzine or other piperazine derivatives
• End-stage renal disease with creatinine clearance under 10 mL/min

Warnings and precautions

• Use caution in moderate and severe renal failure; dose adjustment may be needed.
• The source content mentions a risk of seizure in people with epilepsy or seizure predisposition.
• Use caution with alcohol and central nervous system depressants.
• It is not recommended in children under 2 years according to the source content.
• Cetirizine may interfere with allergy skin testing; the source content notes a 3-day spacing.
• Use caution in patients with factors that may predispose to urinary retention.

Renal insufficiency

The source content highlights renal adjustment and states that cetirizine is contraindicated in end-stage renal disease. It also gives example adult adjustments for reduced creatinine clearance. Children require individualized adjustment based on creatinine clearance, age, and weight.

Pregnancy and breastfeeding

For pregnancy, the source content says animal studies do not indicate harm, but clinical data in pregnancy are very limited, so caution is advised.

For breastfeeding, the source content states that cetirizine is excreted in breast milk and that caution should be exercised when it is prescribed to lactating women.

Driving and machinery

The source content reports that objective measures did not show relevant clinical effects on driving ability, sleep latency, or motor response at the recommended 10 mg dose. Even so, people should consider their own response before driving, using machinery, or doing hazardous activities.

Alcohol or other CNS depressants may further reduce alertness and performance in sensitive individuals.

Possible adverse reactions

The original content lists the following adverse reactions and side effects:

• Drowsiness
• Fatigue
• Headache
• Dizziness
• Dry mouth
• Abdominal pain
• Pharyngitis
• Nausea
• In children 6 months to 12 years: diarrhea and rhinitis

What to verify with the official leaflet

If you are checking cetirizine for yourself or someone else, confirm the following with the official medication guide or a pharmacist:

• The exact product strength and formulation
• Age-appropriate dosing
• Kidney-related dose adjustments
• Whether the product is suitable with other medicines already being used
• Any warnings specific to pregnancy, breastfeeding, or allergy testing

FAQ

Sources and references

The original content cites FDA and U.S. National Library of Medicine resources for cetirizine and recommends consulting the FDA medication guide for full authorized information.