Reactine , Zyrtec
Classifications: antihistamine; h1-receptor antagonist; non-sedating;
Therapeutic: antihistamine, non-sedating
; h1-receptor antagonist
Prototype: Loratidine
Pregnancy Category: B


5 mg, 10 mg tablets; 5 mg, 10 mg chewable tablets; 5 mg/5 mL syrup


Cetirizine is a potent H1-receptor antagonist and thus an antihistamine without significant anticholinergic or CNS activity. Low lipophilicity combined with its H1-receptor selectivity probably accounts for its relative lack of anticholinergic and sedative properties.

Therapeutic Effect

Effectively treats allergic rhinitis and chronic urticaria by eliminating or reducing the local and systemic effects of histamine release.


Seasonal and perennial allergic rhinitis and chronic idiopathic urticaria.


Hypersensitivity to H1-receptor antihistamines or hydroxyzine; concurrent use of alcohol; hepatic or renal dysfunction; lactation, infants <6 mo.

Cautious Use

Moderate to severe renal impairment, pregnancy (category B), children.

Route & Dosage

Allergic Rhinitis
Adult: PO 5–10 mg once/d
Child: PO 2–5 y, 2.5 mg q.d. (max: 5 mg/d); ≥6 y, 5–10 mg q.d.

Chronic Urticaria
Adult: PO 10 mg q.d. or b.i.d.


  • Consult physician about dosage if significant adverse effects appear. As elimination half-life is prolonged in the older adult, dosage adjustments may be warranted.

Adverse Effects (≥1%)

GI: Constipation, diarrhea, dry mouth. CNS: Drowsiness, sedation, headache, depression.


Drug: Theophylline may decrease cetirizine clearance leading to toxicity.


Absorption: Readily from GI tract. Peak: 1 h. Distribution: 93% protein bound; minimal CNS concentrations. Metabolism: Minimal (by CYP3A4). Elimination: 60% unchanged in urine within 24 h, 5% in feces. Half-Life: 7.4 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor for drug interactions. As the drug is highly protein bound, the potential for interactions with other protein-bound drugs exists.
  • Monitor for sedation, especially the older adult.

Patient & Family Education

  • Do not use in combination with OTC antihistamines.
  • Do not engage in driving or other hazardous activities, before experiencing your responses to the drug.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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