Dextromethorphan HBr plateaus

Box 1: “Plateaus” of dextromethorphan toxicity*,2,3. Plateau 0 Total dose 20mg to 45mg. You can barely feel it at all, but it relieves cough. Plateau 0.5 Total dose 45mg to 100mg Antidepressant effects (especially when stacked with 100mg of Wellbutrin SR) Plateau 1 (1.5–2.5 mg/kg) Total intake 100–200 mg (4–6 capsules or 35–60 mL of syrup) Restlessness, euphoria Plateau 2 (2.5–7.5 mg/kg) Total dose 200–500 mg (7–18 capsules or 60–185 mL of syrup) Exaggerated auditory and visual sensations, closed-eye hallucinations, imbalance Plateau 3 (7.5–15 mg/kg) Total dose 500–1000 mg (18–33 capsules or 185–375 mL of syrup) Visual and auditory disturbances, altered consciousness, delayed reaction times, mania, panic, partial dissociation Plateau 4 (> 15 mg/kg) Total dose > 1000 mg (> 33 capsules or > 375 mL of syrup) Hallucinations, delusions, ataxia, complete dissociation *Assuming a 75-kg person, 30-mg capsules and 3 mg per millilitre of syrup.