Hydroxyzine Overdose Management
Hydroxyzine overdose should be managed primarily with supportive care including airway protection, monitoring for QT prolongation/Torsade de Pointes, and treatment of seizures if they occur—there is no specific antidote. 1
Immediate Management
Airway and Breathing
- Establish airway patency and provide respiratory support as the primary intervention
- Consider bag-mask ventilation followed by endotracheal intubation if respiratory depression develops or protective airway reflexes are lost
- Hypersedation is the most common manifestation, requiring close monitoring of respiratory status 1
Gastrointestinal Decontamination
- Induce vomiting if it has not occurred spontaneously
- Perform immediate gastric lavage 1
- These interventions are most effective when performed early after ingestion
Cardiac Monitoring
- Obtain and continuously monitor ECG for QT prolongation and Torsade de Pointes, which are specific risks with hydroxyzine overdose 1
- This distinguishes hydroxyzine from other antihistamines and requires vigilant cardiac surveillance
Clinical Manifestations to Anticipate
Primary Toxicity Profile
Hydroxyzine produces a distinct clinical picture compared to other first-generation antihistamines like diphenhydramine:
- Mild CNS depression is MORE common than antimuscarinic toxidrome 2
- Antimuscarinic findings are LESS common than with diphenhydramine (contrary to what many clinicians expect) 2
- Seizures can occur, particularly in children 3
- Sinus tachycardia may develop 3
- Rare complications include priapism, even at supratherapeutic doses 4
Severity Markers
- Stupor, nausea, and vomiting may occur 1
- Convulsions represent severe toxicity 1
- Mortality is rare (0.02-0.8% in large cohort studies) 2
Specific Treatments
Hypotension Management
- Control with intravenous fluids first-line
- Use levarterenol (norepinephrine) or metaraminol if vasopressors are needed
- DO NOT use epinephrine—hydroxyzine counteracts its pressor action 1
Seizure Management
- Treat seizures with benzodiazepines as first-line
- Physostigmine has been used successfully in pediatric cases with seizures 3, though this is not standard practice
No Role for Specific Antidotes
- There is no specific antidote for hydroxyzine 1
- Hemodialysis is not valuable for hydroxyzine removal alone 1
- Consider hemodialysis only if co-ingestion with dialyzable substances (e.g., barbiturates) has occurred 1
Monitoring and Supportive Care
- Frequent vital sign monitoring and close observation are essential 1
- No practical method exists to quantitate hydroxyzine levels in body fluids 1
- Management decisions are based on clinical presentation, not drug levels
Critical Pitfalls to Avoid
Do not assume antimuscarinic toxidrome: Unlike diphenhydramine, hydroxyzine more commonly causes sedation without prominent anticholinergic features 2
Do not use epinephrine for hypotension: This can worsen hemodynamics due to hydroxyzine's alpha-blocking effects 1
Do not forget cardiac monitoring: QT prolongation and Torsade de Pointes are specific risks that require ECG surveillance 1
Consider polysubstance ingestion: Multiple agents are frequently involved in overdoses, which may alter management 1
Contact poison control: For complex cases, utilize regional poison centers (1-800-222-1222 in the US) for expert toxicology guidance 5