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.
5Total
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.
