Management of Hydroxyzine (Antihistamine) Overdose
The management of hydroxyzine overdose requires supportive care, close monitoring, and treatment of symptoms, as there is no specific antidote available. 1
Initial Assessment and Management
- Assess airway, breathing, and circulation (ABC) immediately upon presentation 2
- Monitor vital signs frequently, with particular attention to blood pressure, heart rate, respiratory rate, and oxygen saturation 1
- Obtain ECG monitoring due to risk of QT prolongation and Torsade de Pointes in hydroxyzine overdose 1
- If the patient presents within 1-2 hours of ingestion and is alert, consider inducing vomiting or performing gastric lavage 1
- Administer activated charcoal if the patient presents within 1 hour of ingestion and has a protected airway 2
Clinical Manifestations to Monitor
- Hypersedation (most common manifestation) 1
- Convulsions 1
- Stupor 1
- Nausea and vomiting 1
- Hypotension (though uncommon) 1
- QT prolongation and potential cardiac arrhythmias 1
Treatment Approach
- Provide general supportive care with close observation of the patient 1
- Manage hypotension with intravenous fluids and vasopressors if needed 1
- For hypotension requiring vasopressor support, use levarterenol or metaraminol; avoid epinephrine as hydroxyzine counteracts its pressor action 1
- Treat seizures if they occur with standard anticonvulsant therapy 2
- For severe sedation, provide respiratory support as needed 1
Monitoring Period
- Observe patients for at least 4-6 hours after ingestion to ensure no delayed toxicity develops 3
- Patients who remain asymptomatic after 4-6 hours of observation may be considered for discharge if medically cleared and psychiatrically stable 3
- Patients showing signs of toxicity require continued monitoring until symptoms resolve 3
Special Considerations
- Hemodialysis is generally not effective for hydroxyzine overdose 1
- If other substances were co-ingested (particularly barbiturates), hemodialysis may be indicated based on those substances 1
- There is no practical method to quantitate hydroxyzine in body fluids or tissue after ingestion 1
Disposition
- Patients with significant sedation, hemodynamic instability, seizures, or cardiac abnormalities require admission for continued monitoring 2
- Psychiatric evaluation should be considered for intentional overdoses once the patient is medically stable 4
- Asymptomatic patients with selected acute intentional ingestions may be released from medical observation in less than six hours if they remain stable 3
Pitfalls and Caveats
- Do not use epinephrine to treat hypotension in hydroxyzine overdose as hydroxyzine counteracts its pressor action 1
- Be aware that hydroxyzine may cause more pronounced sedation in elderly patients or those with hepatic impairment 5
- Consider the possibility of co-ingestions, which may complicate the clinical picture and management 2
- Remember that there is no specific antidote for hydroxyzine overdose, making supportive care the mainstay of treatment 1