What are the treatment options for a Zertec (cetirizine) overdose?

Treatment of Cetirizine (Zyrtec) Overdose

For cetirizine overdose, supportive care is the mainstay of treatment as there is no specific antidote, with monitoring for sedation and potential cardiovascular effects in severe cases.

Initial Assessment and Management

Severity Assessment

• Determine amount ingested and time since ingestion
• Assess for symptoms:
  • Mild to moderate: Drowsiness, sedation
  • Severe: Profound sedation, hypotension, tachycardia, potential QT prolongation

Immediate Interventions

1. Contact Poison Control Center (1-800-222-1222) for guidance 1
2. Supportive care is the primary treatment approach
3. For recent ingestions (within 1-2 hours):
   • Consider activated charcoal if large amounts ingested
   • Do NOT induce vomiting unless directed by Poison Control

Treatment Algorithm Based on Severity

Mild Overdose (minimal symptoms)

• Observation for 2-3 hours
• Monitor for development of sedation
• Home observation may be adequate for small overdoses (less than 3-4 times therapeutic dose) 2

Moderate Overdose (significant sedation)

• Continuous monitoring of vital signs
• IV fluids if hypotensive
• Supportive care for sedation
• Monitor for at least 6 hours

Severe Overdose (cardiovascular symptoms, profound CNS depression)

• Admit to hospital for monitoring
• Cardiac monitoring for potential arrhythmias
• Correct electrolyte abnormalities, particularly hypokalemia
• Support blood pressure with IV fluids and vasopressors if needed
• Consider ICU admission for severe cases

Special Considerations

Cardiovascular Monitoring

• Unlike second-generation antihistamines like terfenadine and astemizole, cetirizine has minimal cardiac toxicity 2
• However, in massive overdose, cardiac monitoring is warranted as a case report documented ventricular fibrillation in a patient with anorexia who took 270mg of cetirizine 3

Risk Factors for Severe Toxicity

• Pre-existing conditions like anorexia may increase risk of severe outcomes 3
• Hypokalemia may exacerbate cardiac toxicity
• Concomitant CNS depressants will potentiate sedative effects

Expected Course and Prognosis

• Most cases resolve within 5-6 hours with supportive care only 4
• Sedation is the most common symptom, which typically resolves without intervention
• Fatal outcomes are extremely rare and usually involve comorbidities or massive doses

Common Pitfalls and Caveats

• Cetirizine is generally safer in overdose than first-generation antihistamines 2
• Do not confuse management with that of cardiotoxic second-generation antihistamines (terfenadine, astemizole)
• Avoid medications that may potentiate sedation
• Monitor for longer periods in patients who have ingested sustained-release formulations
• Consider extended monitoring in patients with renal impairment as cetirizine is primarily eliminated unchanged through the kidneys 5

Follow-up Recommendations

• For intentional overdoses, psychiatric evaluation is warranted
• For accidental pediatric ingestions, provide caregiver education on medication safety
• No specific follow-up testing is typically required after resolution of symptoms

Remember that while cetirizine is generally considered safer than first-generation antihistamines in overdose, significant toxicity can still occur with large ingestions, particularly in patients with underlying risk factors.