Dextromethorphan Overdose Management
For suspected dextromethorphan overdose, immediately assess airway and breathing, activate emergency services, provide supportive care with benzodiazepines for seizures and agitation, consider naloxone for severe CNS/respiratory depression, and refer all patients with more than mild symptoms or ingestions >7.5 mg/kg to the emergency department. 1
Immediate Assessment and Triage
All patients with suicidal intent, intentional abuse, or suspected malicious intent must be referred to an emergency department immediately. 1 Contact Poison Control Center (1-800-222-1222) for all overdose cases. 2
Dose-Based Risk Stratification
- Ingestions of 5-7.5 mg/kg: Initiate poison center follow-up every 2 hours for up to 4 hours post-ingestion; refer to ED if more than mild symptoms develop 1
- Ingestions >7.5 mg/kg: Refer directly to emergency department for evaluation 1
- Asymptomatic patients >4 hours post-ingestion: Can be observed at home with close monitoring 1
Symptom-Based Referral Criteria
Patients exhibiting more than mild effects (frequent vomiting, significant somnolence, altered consciousness, agitation, nystagmus, tachycardia, or any seizure activity) require immediate ED referral. 1, 3 Dextromethorphan toxicity can present with shock, convulsions, and status epilepticus requiring intensive care. 4
Airway and Breathing Management
Secure the airway immediately in patients with altered consciousness (GCS ≤8), respiratory depression, or inability to protect airway. 4, 5 Provide bag-mask ventilation and prepare for endotracheal intubation as needed. 4 This is the highest priority intervention, as respiratory compromise can rapidly progress to respiratory arrest.
Pharmacological Interventions
Naloxone Administration
Naloxone can be considered for prehospital administration in patients who are sedated or comatose with respiratory depression, using usual opioid overdose doses. 1 While dextromethorphan is not a true opioid, it has NMDA receptor antagonist properties and naloxone may provide partial reversal of CNS depression in severe cases. 1
Seizure Management
Administer intravenous benzodiazepines as first-line treatment for seizures. 1 Dextromethorphan can cause both generalized tonic-clonic seizures and status epilepticus, particularly in high-dose ingestions. 4, 3 Continue benzodiazepines rather than adding additional antiepileptic drugs. Seizures may also result from decreased cerebral perfusion secondary to shock. 4
Serotonin Syndrome Management
For hyperthermia >104°F (>40°C) consistent with serotonin syndrome, administer benzodiazepines and implement external cooling measures. 1 Dextromethorphan can cause serotonin syndrome, especially when combined with SSRIs, MAOIs, or other serotonergic medications. 5 Patients on these interacting medications require poison center follow-up every 2 hours for 8 hours. 1
Vasopressor Support
Administer noradrenaline for shock and hypotension refractory to fluid resuscitation. 4 High-dose dextromethorphan can cause cardiovascular collapse requiring intensive vasopressor support. 4
Gastrointestinal Decontamination
Do not induce emesis. 1 Do not administer activated charcoal at home. 1 Activated charcoal may be administered by healthcare professionals to asymptomatic patients within 1 hour of ingestion if no contraindications exist, but do not delay transportation to administer it. 1 Gastric lavage can be performed after airway protection in severe cases presenting early. 4
Monitoring and Observation
All symptomatic patients require continuous monitoring in a healthcare setting until risk of recurrent toxicity is low and vital signs have normalized. 1 Monitor for:
- Altered consciousness and confusion (can persist 24+ hours) 5
- Respiratory depression 1, 4
- Seizure activity 4, 3
- Cardiovascular instability and shock 4
- Horizontal nystagmus and ataxia 3
- Agitation and psychosis 5
Critical Pitfalls to Avoid
Do not dismiss dextromethorphan toxicity as benign—severe cases can present with shock, status epilepticus, and deep coma requiring mechanical ventilation. 4, 5 Standard urine drug screens are negative for dextromethorphan, so toxicity may be missed if not specifically considered. 3 Always obtain detailed history about over-the-counter medication use and online purchases. 4
Consider dextromethorphan abuse in young adults presenting with new-onset seizures, especially with negative standard drug screens and horizontal nystagmus. 3 The presentation can masquerade as primary seizure disorders. 3
Carefully assess for co-ingestion of acetaminophen and other medications in combination products, as these may require specific additional interventions. 1
Disposition
All patients with intentional overdose require psychiatric evaluation before discharge. 4 Refer to drug rehabilitation programs for confirmed abuse cases. 3 Dextromethorphan abuse is particularly common in younger adolescents, and early identification may prevent progression to broader substance abuse. 6