Cetirizine: Nursing Drug Guide, Sedation & Renal Dosing

Cetirizine hydrochloride (HCl) is a selective peripheral H₁-receptor antagonist available as tablets, chewables, orally disintegrating tablets, and oral solution. This guide focuses on common oral products reviewed in current U.S. OTC labeling and prescribing information.

• Tablets / chewables: Zyrtec; Reactine (Canada); multiple generic 5 mg and 10 mg strengths
• Oral solution: 1 mg/mL (5 mg per 5 mL teaspoonful) — pediatric and adult liquid dosing per product label
• Related agents: Levocetirizine (active R-enantiomer); parent compound hydroxyzine — cross-sensitivity contraindication
• Not interchangeable with: sedating first-generation antihistamines such as diphenhydramine on sedation profile or dosing

Per U.S. OTC cetirizine tablet labeling and prescribing information:

• OTC: Temporary relief of hay fever or upper respiratory allergy symptoms — runny nose, sneezing, itchy/watery eyes, itchy nose or throat
• Prescription oral solution (U.S.): Perennial allergic rhinitis and uncomplicated chronic idiopathic urticaria in defined pediatric age groups per that product’s labeling
• Health Canada monograph: Seasonal and perennial allergic rhinitis and chronic idiopathic urticaria in adults and children per labeled ages

Nurses use cetirizine for nasal congestion, rhinorrhea, pruritus, and hives. It does not replace epinephrine or emergency therapy for anaphylaxis.

Cetirizine is an orally active, selective H₁-receptor antagonist (human metabolite of hydroxyzine). Principal effects are mediated via peripheral H₁ blockade with negligible anticholinergic activity in animal models; however, dry mouth occurred more often than placebo in clinical studies per prescribing information.

Autoradiographic and clinical data indicate low CNS penetration relative to first-generation antihistamines, but labeling still warns that drowsiness may occur and that alcohol and sedatives increase sedation.

Oral route only. Match tablet strength (5 mg vs 10 mg) and formulation to the order and product label.

U.S. OTC tablets (10 mg)

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Prescription / product monograph (selected)

Renal dose adjustment (Health Canada monograph)

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U.S. OTC labeling does not print this table—nurses in acute care should use prescriber orders and pharmacy review when eGFR declines.

• Absorption: Rapid; T_max ~1 hour after oral tablet or solution
• Food: May be taken without regard to food (oral solution labeling); high-fat meal can delay T_max and lower C_max per prescribing information
• Half-life: Mean ~8.3 hours in healthy adults; prolonged in renal dysfunction
• Elimination: ~70% urinary excretion as unchanged drug; renal clearance drives dosing in kidney disease
• Protein binding: ~93%

Answer these before the first dose or when reconciling home supply:

• Correct patient, drug, strength (5 mg vs 10 mg), route (oral), and scheduled time
• Only one sedating antihistamine on MAR and home list (cetirizine vs loratadine, fexofenadine, diphenhydramine, or intranasal azelastine)
• Total cetirizine in last 24 hours — OTC max one 10 mg tablet unless prescriber ordered otherwise
• Recent alcohol, opioids, benzodiazepines, or tranquilizers — labeling warns increased drowsiness
• Renal function — review basic metabolic panel / creatinine; eGFR may require 5 mg or less frequent dosing
• Occupation requiring alertness (driving, machinery, night shift)
• Hypersensitivity to cetirizine, hydroxyzine, or formulation excipients (e.g., lactose in some tablets)
• Pregnancy or breastfeeding — OTC: ask health professional if pregnant; breastfeeding not recommended on U.S. OTC label

• Known hypersensitivity to cetirizine, any ingredient, or hydroxyzine (U.S. OTC and Health Canada monograph)
• Severe renal impairment — creatinine clearance <10 mL/min per Health Canada monograph (contraindicated)

U.S. OTC labeling uses “Do not use” if allergic to this product, its ingredients, or an antihistamine containing hydroxyzine.

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No clinically significant interactions with pseudoephedrine, ketoconazole, erythromycin, or azithromycin were observed in labeling interaction studies at therapeutic cetirizine doses.

• Oral administration with or without food per product label
• Use calibrated oral syringe or cup for solution — 1 mg/mL (5 mg per 5 mL)
• Chewable or ODT products: follow label for swallowing vs dissolving
• Document exact strength, time, and total daily dose from all sources (unit dose + patient-owned OTC)

• Reduced sneezing, rhinorrhea, nasal/ocular itching, and urticaria pruritus over hours to days
• Peak effect on histamine wheal-and-flare suppression persists ≥24 hours at labeled doses in pharmacodynamic studies
• If inadequate response, prescriber may increase within monograph limits (e.g., up to 20 mg/day Rx) — not by unsupervised OTC double-dosing

• Anaphylaxis or serious allergic reaction (urticaria with angioedema, bronchospasm, hypotension) — postmarketing reports include anaphylaxis; stop drug and treat per emergency pathway
• Severe somnolence, confusion, or inability to arouse — especially with sedating co-medications
• Signs of hepatitis (jaundice, dark urine) — hepatitis reported in association with cetirizine per monograph
• Aggressive behavior, hallucinations, or suicidal ideation — rare postmarketing reports
• Rebound pruritus within days after long-term use stopped — postmarketing report; notify prescriber

Common adverse reactions per product labeling and trials:

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Postmarketing: anaphylaxis, aggressive reaction, convulsions, hepatitis, thrombocytopenia, stillbirth (causal relationship not established for all). Report per facility policy.

Overdosage has been reported. An adult who took 150 mg was somnolent without other major abnormalities in labeling. In an 18-month-old who took ~180 mg, initial restlessness and irritability were followed by drowsiness.

Antidote

No known specific antidote per prescribing information. Treatment is symptomatic and supportive, considering co-ingestants.

• Cetirizine is not effectively removed by dialysis unless a dialyzable co-ingestant was taken
• Oral antihistamine ingestion can seriously harm young children — secure all formulations

• Cetirizine vs levocetirizine — different strengths and renal tables; verify product name
• Cetirizine vs hydroxyzine — related chemistry; hypersensitivity to hydroxyzine contraindicates cetirizine
• Zyrtec vs Zyrtec-D — D product contains pseudoephedrine; not interchangeable
• 5 mg vs 10 mg tablets — double-strength error in older adults and renal patients
• Hospital formulary vs patient OTC bottle — duplicate dosing when both are available

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Monitor

• Level of sedation, dizziness, and safe performance of alertness-dependent tasks
• Allergy symptom relief (rhinitis, urticaria, pruritus)
• Renal function trend when ordered or clinically indicated
• Signs of systemic allergic reaction after first doses
• GI and CNS adverse effects in older adults

Document

• Dose, strength, time, route, and 24-hour total from all sources
• Home OTC reconciliation and duplicate-antihistamine counseling
• Renal dose verification when eGFR or creatinine changes
• Prescriber notification if somnolence limits safe work or discharge

• Take only as directed — no more than one 10 mg OTC tablet in 24 hours unless prescriber says otherwise
• Drowsiness can occur — avoid driving or hazardous tasks if sleepy; avoid alcohol and sedating allergy medicines unless approved
• Bring all allergy bottles to appointments so the team sees duplicates (Zyrtec = cetirizine)
• Seek urgent care for throat swelling, trouble breathing, or widespread rash
• Kidney or liver problems, age 65+, pregnancy, or breastfeeding — talk with prescriber before starting OTC product
• Keep tablets and liquid out of reach of children — overdose causes serious CNS effects in toddlers

Do not give and contact the prescriber/pharmacist when:

Hold parameters may vary by institutional protocol. Follow prescriber orders, pharmacy guidance, and facility policy.