Acetaminophen Dosing for an 80-Pound Child with Fever
For an 80-pound (36.4 kg) child with fever, give acetaminophen 10-15 mg/kg per dose (approximately 360-545 mg), administered every 4-6 hours as needed, not exceeding 60 mg/kg per day (approximately 2,184 mg/day) or 5 doses in 24 hours. 1
Weight-Based Calculation
- An 80-pound child weighs approximately 36.4 kg (80 lbs ÷ 2.2 = 36.4 kg)
- Single dose range: 364-546 mg (10-15 mg/kg × 36.4 kg) 1
- Practical dosing: Give 400-500 mg per dose using available formulations (typically 160 mg/5 mL liquid or tablets) 2
- Maximum daily dose: 2,184 mg (60 mg/kg × 36.4 kg), which should never be exceeded 1
Dosing Interval and Frequency
- Administer every 4-6 hours as needed for fever or discomfort 1
- Do not give more than 5 doses in 24 hours, regardless of the interval used 1
- Oral syrup formulation is absorbed more rapidly and provides more consistent response compared to rectal suppositories 1
Key Safety Considerations
- The 10 mg/kg dose is more conservative and commonly used in the UK, while 15 mg/kg is standard in Australia and the US for adequate antipyretic effect 3, 4
- Doses below 10 mg/kg may provide inadequate fever control, as studies show minimal antipyretic effect at 5 mg/kg 4
- Chronic overdosing (>140 mg/kg/day for several days) carries risk of serious hepatotoxicity, even though single therapeutic doses are remarkably safe 3
- For this 36.4 kg child, never exceed approximately 2,200 mg in 24 hours to maintain the safety margin 1
Clinical Context for Fever Management
- Acetaminophen will improve comfort but does not prevent febrile seizures, as demonstrated in multiple randomized controlled trials 5
- For children with history of febrile seizures, acetaminophen 15 mg/kg can be given prophylactically at the time of vaccination and every 4 hours for 24 hours, though this prevents vaccine-related fever discomfort rather than seizure recurrence 5, 1
- Fever alone requires no treatment unless associated with discomfort or pain, at which point acetaminophen offers effective relief 3
Common Pitfalls to Avoid
- Underdosing is common in practice: Studies show 27% of parents give less than 10 mg/kg, resulting in inadequate fever control 6
- Overdosing also occurs: 12% of parents in one study gave 20 mg/kg or more per dose, risking toxicity with repeated administration 6
- Do not confuse maximum single dose with maximum daily dose: A 15 mg/kg single dose is appropriate, but cumulative daily exposure must stay under 60 mg/kg 1
- Avoid combining with other acetaminophen-containing products (many cold/flu medications contain acetaminophen), as this increases risk of inadvertent overdose 3