From the FDA Drug Label
The most common manifestation of hydroxyzine overdosage is hypersedation. Other reported signs and symptoms were convulsions, stupor, nausea and vomiting. ... Hydroxyzine overdose may cause QT prolongation and Torsade de Pointes The following are associated with Atarax (hydroxyzine) overdose:
- Hypersedation
- Convulsions
- Stupor
- Nausea and vomiting
- QT prolongation
- Torsade de Pointes 1
From the Research
Hydroxyzine (Atarax) overdose is associated with sedation, confusion, hallucinations, and in severe cases, seizures or respiratory depression, with a lower likelihood of antimuscarinic findings compared to diphenhydramine poisoning, as shown in a recent cohort analysis 2.
Key Associations
- Sedation
- Confusion
- Hallucinations
- Blurred vision
- Dry mouth
- Urinary retention
- Tachycardia
- Hyperthermia
- Seizures or respiratory depression in severe cases
- QT interval prolongation, potentially leading to cardiac arrhythmias, as highlighted in a study on the risk of QT prolongation and torsade de pointes associated with hydroxyzine use 3
Important Considerations
- Children are particularly susceptible to CNS effects and may experience paradoxical excitation
- Treatment is primarily supportive, focusing on maintaining airway, breathing, and circulation
- Activated charcoal may be administered if the ingestion was recent
- Benzodiazepines can help manage seizures, while physostigmine might be considered for severe anticholinergic symptoms under careful medical supervision
- Cardiac monitoring is important due to potential QT prolongation, as emphasized in a study on the cardiac safety profile of hydroxyzine 3
- Most patients recover fully with appropriate supportive care, though severe overdoses can be life-threatening, particularly in patients with pre-existing cardiac conditions or when hydroxyzine is combined with other CNS depressants
Recent Findings
- A cohort analysis of antimuscarinic effects in hydroxyzine and diphenhydramine-poisoned patients found that hydroxyzine-poisoned patients had lower rates and relative risk of developing antimuscarinic findings or receiving physostigmine 2
- The clinical manifestations of hydroxyzine exposures are consistent with the pharmacology of hydroxazine, and clinicians should not generalize the illness script of diphenhydramine exposures to hydroxyzine exposures 2