What is the appropriate management for a suspected hydroxyzine overdose?

Management of Hydroxyzine Overdose

The most common manifestation of hydroxyzine overdose is hypersedation, and management centers on aggressive supportive care with airway protection, gastric decontamination if appropriate, ECG monitoring for QT prolongation, and benzodiazepines for seizures—there is no specific antidote. 1

Immediate Assessment and Stabilization

• Check for responsiveness, activate emergency response immediately, and assess breathing and pulse within 10 seconds. 2
• Establish continuous cardiac monitoring with serial ECGs to detect QT prolongation and potential Torsade de Pointes, which are documented complications of hydroxyzine overdose. 1
• Secure IV access, perform bedside glucose testing, and monitor vital signs continuously. 3
• Open the airway using head-tilt/chin-lift or jaw-thrust maneuver if respiratory depression is present. 2
• Prepare for endotracheal intubation if Glasgow Coma Scale ≤8 or if respiratory status deteriorates despite bag-mask ventilation. 3

Gastric Decontamination

• Induce vomiting if it has not occurred spontaneously, according to FDA labeling. 1
• Perform immediate gastric lavage as recommended in the FDA label for hydroxyzine overdose. 1
• Do not delay definitive care or transportation to administer activated charcoal in the prehospital setting. 4

Management of Specific Complications

Central Nervous System Effects

• Hydroxyzine overdose typically presents with mild-to-moderate CNS depression rather than antimuscarinic toxidrome, unlike diphenhydramine. 5
• Administer benzodiazepines (diazepam first-line or midazolam) for seizures if they occur. 6, 3
• Continue benzodiazepines as primary anticonvulsant therapy rather than adding additional antiepileptic drugs. 3
• Physostigmine has been used successfully for seizure control in documented pediatric hydroxyzine toxicity, though this is not standard first-line therapy. 7

Cardiovascular Complications

• Monitor continuously for QT prolongation and ventricular dysrhythmias, particularly Torsade de Pointes. 1
• Treat hypotension with intravenous fluids and levarterenol or metaraminol if needed. 1
• Do NOT use epinephrine, as hydroxyzine counteracts its pressor action. 1
• Be aware that hydroxyzine may produce abnormal ventricular repolarization, especially in substantial doses or susceptible individuals. 8

Respiratory Support

• Provide bag-mask ventilation immediately if respiratory effort is inadequate and continue until spontaneous breathing returns. 2
• Mechanical ventilation is indicated if respiratory depression persists despite initial interventions. 3

Laboratory and Diagnostic Workup

• Perform urine drug screen to identify co-ingestants, particularly opioids, alcohol, or other CNS depressants. 3
• Obtain serum acetaminophen and salicylate levels as part of standard overdose workup. 3, 9
• Perform comprehensive metabolic panel including electrolytes, creatinine, and serum osmolarity. 9
• Serial ECGs are essential to monitor QT interval and detect dysrhythmias. 1
• Note that there is no practical method to quantitate hydroxyzine in body fluids or tissue after ingestion. 1

Antidote and Extracorporeal Considerations

• There is no specific antidote for hydroxyzine overdose. 1
• Hemodialysis is doubtful to be of value for hydroxyzine overdose alone, but may be indicated if barbiturates or other dialyzable agents were co-ingested. 1

Observation and Disposition

• Observe all patients in a healthcare setting until the risk of recurrent toxicity is low and vital signs have normalized. 2, 3
• Minimum observation period of 6–8 hours for patients who remain asymptomatic. 3
• ICU admission is indicated for respiratory depression requiring mechanical ventilation, QT prolongation, or cardiac arrhythmias. 3
• Mandatory psychiatric evaluation is required before discharge for intentional overdoses to assess suicide risk. 3
• Mortality from hydroxyzine overdose is rare (0.02% in large national datasets), and complete recovery within 72 hours is typical with supportive care. 5, 7

Common Pitfalls to Avoid

• Do not assume hydroxyzine overdose will present with prominent antimuscarinic findings like diphenhydramine—hydroxyzine causes more sedation and fewer anticholinergic effects. 5
• Do not use epinephrine for hypotension, as it is specifically contraindicated due to hydroxyzine's antagonism of its pressor effects. 1
• Do not overlook ECG monitoring—QT prolongation and Torsade de Pointes are well-documented complications requiring continuous cardiac surveillance. 1
• Do not delay emergency activation while attempting interventions; immediate activation is essential even in seemingly stable patients. 2
• Be aware that co-ingestion with drugs affecting cardiac repolarization (phenothiazines, tricyclic antidepressants, quinidine, procainamide) may augment QT prolongation and increase dysrhythmia risk. 8