How should I assess and manage an adolescent or young adult abusing high‑dose dextromethorphan (DXM)?

Assessment and Management of Dextromethorphan (DXM) Abuse in Adolescents

Immediate Assessment Priorities

All adolescents presenting with suspected or confirmed DXM abuse require immediate evaluation for suicidal intent, intentional abuse, or malicious circumstances (e.g., peer pressure, coercion), and should be referred to an emergency department. 1

Clinical Presentation Recognition

DXM produces dose-dependent toxicity with effects similar to phencyclidine (PCP), including:

• Altered mental status with confusion, agitation, or flat affect 2, 3
• Horizontal nystagmus (key physical finding) 3
• Tachycardia (heart rate >110 bpm) 3
• Seizure-like activity or tonic-clonic movements that may be misdiagnosed as new-onset epilepsy 3
• Dissociative symptoms ranging from mild euphoria to complete dissociation depending on dose 2, 4
• Respiratory depression in severe cases 1
• Hyperthermia (>104°F) with serotonin syndrome 1

Critical History Elements

Obtain specific information about:

• Exact dose ingested: Megadoses are defined as 5-10 times therapeutic doses; >7.5 mg/kg requires ED referral 1, 4
• Formulation used: Coricidin HBP Cough & Cold tablets ("triple C"), pure powder from internet sources, or cough syrups 4
• Co-ingested substances: Acetaminophen, chlorpheniramine, guaifenesin, pseudoephedrine add significant toxicity 4
• Concurrent medications: SSRIs, MAOIs, or other serotonergic drugs dramatically increase risk of serotonin syndrome 5, 1
• Timing of ingestion: Symptoms typically appear within 2-4 hours 1
• Suicidal ideation or intent 1
• Pattern of use: Frequency, duration, escalation, and social context (parties, before/after school) 4

Emergency Department Referral Criteria

Refer immediately to ED if any of the following are present:

• More than mild symptoms (beyond light somnolence or infrequent vomiting) 1
• Ingestion >7.5 mg/kg 1
• Seizure activity or suspected seizures 3
• Altered mental status beyond mild sedation 1
• Respiratory depression 1
• Hyperthermia >104°F 1
• Concurrent use of SSRIs or MAOIs (serotonin syndrome risk) 5, 1
• Any suicidal intent or malicious circumstances 1

Outpatient Monitoring Protocol

For patients with ingestion of 5-7.5 mg/kg who are asymptomatic or mildly symptomatic:

• Poison center-initiated follow-up every 2 hours for up to 4 hours post-ingestion 1
• Refer to ED if more than mild symptoms develop during observation 1
• Patients asymptomatic >4 hours post-ingestion can be observed at home 1
• If concurrent SSRI/MAOI use: extend monitoring to every 2 hours for 8 hours 1

Acute Management in Emergency Setting

Decontamination

• Do NOT induce emesis 1
• Do NOT administer activated charcoal at home 1
• Activated charcoal may be given by healthcare professionals within 1 hour of ingestion if no contraindications exist, but do not delay transport 1

Pharmacological Interventions

• Naloxone in standard opioid overdose doses for sedated/comatose patients with respiratory depression (prehospital administration appropriate) 1
• Intravenous benzodiazepines for seizure control 1
• Benzodiazepines plus external cooling for hyperthermia >104°F associated with serotonin syndrome 1

Diagnostic Testing

• Urine drug screen: May produce false-positive for phencyclidine (PCP) 4
• Serum DXM level: Therapeutic range is ~100 ng/mL; toxic levels can exceed 900-1000 ng/mL 3
• Acetaminophen level: Essential if co-ingestion suspected 1, 4
• Comprehensive metabolic panel: Assess for complications 3
• ECG: Rule out arrhythmias, especially with co-ingested substances 3

Substance Abuse Assessment

Before initiating any treatment for co-occurring conditions (e.g., ADHD), assess for substance abuse symptoms and ensure the patient is off abusive substances. 5

Screening Tools

• CRAFFT screening tool (Car, Relax, Alone, Forget, Friends, Trouble): Takes <2 minutes, validated for adolescents, can be interview or self-report 5
• Screen for alcohol and other illicit drug use, which is highly associated with DXM abuse 6

Risk Factors for DXM Abuse

• Easy accessibility: Over-the-counter availability, no prescription required 4, 6
• Low cost: Inexpensive or easily shoplifted 4
• Decreased perception of harm: "Legal" status reduces perceived danger 6
• Internet availability: Pure powder available in gram quantities from websites including eBay 4
• Peer influence: Use at parties, social settings 4
• Co-occurring mental health conditions: Bipolar disorder, depression 3

Pharmacogenetic Consideration

Approximately 5% of persons of European ethnicity lack normal CYP2D6 metabolism, leading to rapid accumulation of toxic DXM levels even at lower doses. 4 This population is at higher risk for severe toxicity.

Behavioral Intervention and Referral

Immediate Actions

• Refer all cases with suicidal intent, intentional abuse, or malicious circumstances to ED 1
• Mandatory referral to drug rehabilitation program for confirmed abuse 3
• Assess for substance use disorder: Adolescents meeting DSM criteria require formal treatment, not just prevention interventions 5

Prevention Counseling

The evidence for behavioral interventions to prevent drug use in adolescents is limited, with only 6 fair-to-good quality studies showing minimal improvements in health outcomes 5. However:

• Early identification and treatment of DXM abuse may prevent broader substance abuse progression 2
• Address the serious potential for harm despite "legal" status 6
• Educate about risks: altered judgment leading to injury, potential for dependence, co-ingestion toxicity 6
• Discuss consequences beyond frequent use: risk-taking behaviors while intoxicated (driving, unsafe sexual activity, violence) 5

Family Involvement

• Educate parents about DXM abuse signs: empty medication bottles, internet searches for extraction methods, behavioral changes 4
• Secure medications at home: Lock cabinets, monitor inventory 5
• Screen family members for substance abuse: Parents or family may abuse the adolescent's medications 5

Common Pitfalls to Avoid

• Misdiagnosing DXM toxicity as new-onset seizure disorder: Always consider DXM abuse in adolescents presenting with unexplained seizure-like activity 3
• Relying solely on urine drug screen: Standard screens do not detect DXM and may show false-positive for PCP 4, 3
• Missing co-ingested substances: Acetaminophen toxicity can be life-threatening and requires specific management 1, 4
• Failing to assess for serotonin syndrome: Particularly dangerous with concurrent SSRI/MAOI use 5, 1
• Underestimating accessibility: Pure powder and concentrated forms are easily obtained online 4
• Assuming "legal" means "safe": Over-the-counter status creates false sense of security among adolescents 6

Follow-Up and Monitoring

• Cancel unnecessary diagnostic testing (e.g., epilepsy workup) once DXM abuse confirmed 3
• Coordinate with drug rehabilitation services for ongoing treatment 3
• Monitor for polysubstance abuse: High association with alcohol and other illicit drugs 6
• Reassess at regular intervals for treatment adherence and relapse prevention 5