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.
