What is the management for a dextromethorphan (cough syrup) overdose with no co-administered drugs?

Management of Dextromethorphan Overdose

For isolated dextromethorphan overdose, the cornerstone of management is supportive care with close monitoring, as most patients recover fully with symptomatic treatment alone. 1

Immediate Triage and Disposition

All patients with suicidal intent or intentional abuse must be referred to an emergency department immediately. 1

Dose-Based Risk Stratification

• Ingestions >7.5 mg/kg require emergency department evaluation due to increased risk of severe toxicity 1
• Ingestions of 5-7.5 mg/kg warrant poison center follow-up every 2 hours for up to 4 hours post-ingestion, with ED referral if more than mild symptoms develop 1
• Asymptomatic patients >4 hours post-ingestion can be observed at home 1

Symptom-Based Referral Criteria

Patients exhibiting more than mild effects (frequent vomiting, significant somnolence, altered consciousness, seizures) require immediate ED referral. 1 Severe overdoses can present with refractory status epilepticus, shock, and reversible cranial nerve reflex loss, necessitating intensive care 2, 3

Emergency Department Management

Airway and Supportive Care Priority

The primary focus is aggressive supportive care, particularly airway management and seizure control. 2, 3

• Endotracheal intubation is indicated for patients with altered consciousness, refractory seizures, or respiratory depression 2, 3
• Standard BLS/ACLS protocols take precedence over specific antidotal therapy 4

Decontamination Considerations

• Do not induce emesis 1
• Activated charcoal may be considered only if the patient presents within 1 hour of ingestion, is asymptomatic, has no contraindications, and administration does not delay transport 1
• Gastric lavage can be performed after intubation in severe cases presenting early 3

Seizure Management

Use intravenous benzodiazepines as first-line therapy for seizures. 1 Refractory status epilepticus may require propofol and midazolam infusions in the ICU setting 2

Naloxone Consideration

For sedated or comatose patients with respiratory depression, naloxone in usual opioid overdose doses can be considered for prehospital or ED administration. 1 However, dextromethorphan is not a true opioid, and naloxone response is inconsistent—do not delay other supportive measures while awaiting naloxone effect 1

Serotonin Syndrome Management

If hyperthermia >40°C (104°F) develops, administer benzodiazepines and implement external cooling measures immediately. 1 This is particularly relevant if the patient takes serotonergic medications (SSRIs, MAOIs), which dramatically increases risk even at lower dextromethorphan doses 1

Hemodynamic Support

Shock from massive dextromethorphan overdose requires vasopressor support with norepinephrine. 3 Monitor for decreased cerebral perfusion pressure, which can precipitate seizures 3

Monitoring and Observation

Duration of Observation

• Asymptomatic patients require 4 hours of observation post-ingestion 1
• Patients on serotonergic medications need poison center follow-up every 2 hours for 8 hours due to prolonged serotonin syndrome risk 1
• Severe cases may require ICU admission for several days until neurological recovery is complete 2

Clinical Course Expectations

Most patients with isolated dextromethorphan overdose improve with supportive care alone 1, 5, 6. Even massive overdoses (>20,000 mg) can result in full recovery without sequelae if intensive supportive care is provided 2. Pediatric accidental ingestions typically present with mild lethargy only and rarely require hospitalization 6

Critical Pitfalls to Avoid

• Never assume dextromethorphan is the only ingestion—carefully assess for co-ingested substances, particularly acetaminophen, which is commonly combined in cough preparations and requires specific antidotal therapy 1
• Do not delay emergency transport to administer activated charcoal 1
• Do not rely on naloxone as definitive treatment—it may provide partial benefit but is not a substitute for comprehensive supportive care 1
• Do not underestimate the severity of intentional overdoses—these can cause life-threatening complications including refractory seizures and shock requiring ICU-level care 2, 3

Pharmacokinetic Considerations

In severe overdoses, dextromethorphan itself (rather than its metabolite dextrorphan) appears responsible for toxicity, with serum concentrations decreasing over 2-4 days 2. This prolonged elimination supports the need for extended monitoring in severe cases 2.