What should be done for a relative who has overdosed on dextromethorphan (+ guaifenesin) syrup, experiencing hallucinations and a 'floating' sensation?

Dextromethorphan Overdose Management

Contact poison control immediately (1-800-222-1222) and transport your relative to the emergency department now—the "floating" sensation indicates significant CNS toxicity from dextromethorphan overdose that requires medical evaluation and monitoring. 1, 2

Immediate Actions Required

• Call poison control center right away for expert toxicology guidance, as board-certified medical toxicologists can provide specialized treatment recommendations for this specific overdose 3, 1
• Transport to emergency department immediately because your relative is experiencing more than mild symptoms (the dissociative "floating" sensation indicates moderate-to-severe CNS effects) 2
• Do not induce vomiting at home—this is contraindicated in dextromethorphan overdose 2
• Do not attempt activated charcoal at home—if indicated, this should only be administered by healthcare professionals in a medical setting 2

Why Emergency Evaluation Is Critical

• Dextromethorphan causes dose-dependent CNS effects ranging from mild sedation to severe dissociation, hallucinations, and psychosis at high doses (>1500 mg/day can induce PCP-like psychological symptoms including delusions and paranoia) 4
• The "floating" sensation your relative describes is a dissociative symptom indicating significant drug effect that requires medical monitoring 4
• Patients who exhibit more than mild effects after acute dextromethorphan ingestion should be referred to an emergency department 2
• Any patient who has ingested more than 7.5 mg/kg should be referred to emergency department for evaluation 2

Specific Risks to Monitor For

Serotonin Syndrome Risk

• If your relative takes antidepressants (SSRIs, SNRIs), MAO inhibitors, or other serotonergic medications, the risk of life-threatening serotonin syndrome is significantly elevated 5
• Dextromethorphan increases serotonin levels, and combining it with other serotonergic medications can cause potentially fatal serotonin toxicity characterized by agitation, confusion, rapid heart rate, high blood pressure, dilated pupils, muscle rigidity, and hyperthermia 5

Respiratory Depression

• Dextromethorphan can cause respiratory depression in overdose, similar to opioids 2
• Naloxone may be considered by emergency medical services if respiratory depression develops, though dextromethorphan is not a true opioid 2

Severe Psychiatric Symptoms

• Dextromethorphan-induced psychosis can include severe delusions, hallucinations, paranoia, and dangerous behaviors including suicidal and homicidal ideation 6, 4
• One documented case involved a middle-aged woman who attempted to kill both herself and a relative after excessive dextromethorphan use 6

What Emergency Department Will Do

• Establish airway patency and monitor respiratory function, providing bag-mask ventilation or intubation if needed 3
• Monitor vital signs continuously including oxygen saturation, blood pressure, heart rate, and temperature 7
• Perform serial neurological assessments to track level of consciousness and watch for worsening symptoms 7
• Treat seizures with intravenous benzodiazepines if they occur 2
• Manage hyperthermia (>104°F/40°C) with benzodiazepines and external cooling if serotonin syndrome develops 2
• Provide supportive care as there is no specific antidote for dextromethorphan overdose 2

Critical Information to Provide

When you arrive at the emergency department or call poison control, have this information ready:

• Exact product name and formulation (dextromethorphan + guaifenesin syrup) 2
• Total amount ingested (how many milliliters or bottles) 2
• Time of ingestion (when did they take it) 2
• All other medications your relative takes, especially antidepressants, MAO inhibitors, or any serotonergic drugs 5, 2
• Current symptoms beyond the floating sensation (confusion, agitation, hallucinations, rapid heartbeat, fever, muscle stiffness) 2
• Whether this was intentional abuse, accidental overdose, or suicidal intent (this affects disposition and psychiatric evaluation needs) 2

Guaifenesin Component

• The guaifenesin in the combination product is generally not toxic and works as an expectorant to thin mucus 8
• Guaifenesin does not cause the CNS effects your relative is experiencing—the dextromethorphan is responsible for the "floating" sensation and dissociative symptoms 8, 4

Common Pitfall to Avoid

Do not assume this will resolve on its own at home—while isolated dextromethorphan overdose can be managed with supportive care and has good prognosis when treated appropriately, the dissociative symptoms indicate significant toxicity requiring medical evaluation 2, 4. Dextromethorphan is not detected on standard urine drug screens, so you must specifically inform healthcare providers about this ingestion 4.