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 agents. 5 Patients on these medications require poison center follow-up every 2 hours for 8 hours. 1
Hemodynamic Support
Administer vasopressors (noradrenaline) for shock refractory to fluid resuscitation. 4 High-dose dextromethorphan ingestions can cause profound hypotension requiring intensive vasopressor support. 4
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 intubation in severe cases presenting early. 4
Monitoring and Observation
Observe all symptomatic patients in a healthcare setting until vital signs normalize and risk of recurrent toxicity is low. 1 Monitor for:
- Altered consciousness and confusion (may persist 24+ hours) 5
- Respiratory depression requiring mechanical ventilation 4, 5
- Seizure activity and status epilepticus 4, 3
- Hemodynamic instability and shock 4
- Horizontal nystagmus and dissociative symptoms 3
Minimum observation period of 4 hours for asymptomatic patients; longer for symptomatic cases or suspected drug interactions. 1, 5
Critical Pitfalls to Avoid
- Do not dismiss new-onset seizures in young adults without considering dextromethorphan abuse - standard urine drug screens do not detect dextromethorphan, and toxicity can masquerade as primary seizure disorders 3
- Do not overlook serotonin syndrome - dextromethorphan interactions with psychiatric medications (SSRIs, MAOIs, antipsychotics) can cause life-threatening serotonin toxicity even at therapeutic doses 5
- Do not underestimate severity based on "over-the-counter" status - high-dose ingestions can cause shock, status epilepticus, and require ICU-level care 4
- Always assess for co-ingestions, particularly acetaminophen, which is commonly combined with dextromethorphan in cough preparations 1
Disposition
All patients require psychiatric evaluation before discharge if intentional overdose. 4 Refer to substance abuse treatment programs for confirmed abuse cases. 3 Early identification and intervention in younger adolescents may prevent progression to broader substance abuse. 6