An 18-month-old child who weighs 17 kg has a fever. Acetaminophen (Tylenol) 15 mg/kg is ordered. How many milligrams should be given?

• A. 120
• B. 255
• C. 200
• D. 148

Answer: (B)

Dosing in children uses mg per kg. To find how many milligrams to give, multiply the child’s weight by the prescribed milligrams per kilogram. Here, 17 kg × 15 mg/kg = 255 mg. So the single dose should be 255 mg. This amount corresponds to the typical per-dose guideline of 15 mg/kg for acetaminophen, and is within usual safety limits for a one-time dose, with the total daily dose limited by the standard 75 mg/kg/day maximum and the dosing interval. If you needed the liquid amount, you would convert 255 mg to milliliters using the suspension’s concentration, but the required dose in milligrams is 255 mg.