Acetaminophen Dosing in Children
The recommended dose of acetaminophen for children is 10-15 mg/kg per dose, administered every 4-6 hours, with a maximum of 5 doses per day (not exceeding 75 mg/kg/day or 4000 mg/day, whichever is lower). 1, 2
Standard Dosing Regimen
Single Dose
- 10-15 mg/kg per dose is the evidence-based range that provides effective antipyretic and analgesic effects 3, 1, 2
- Doses below 10 mg/kg have minimal antipyretic effect, while 20 mg/kg as a single dose is more effective than 10 mg/kg 3
- A loading dose of 25 mg/kg followed by maintenance doses of 12.5 mg/kg every 6 hours can be used for optimal effect 3
Dosing Interval
Maximum Daily Dose
- 75 mg/kg/day for children, but never exceeding 4000 mg/day regardless of weight 2
- In the UK and Australia, total daily doses range from 40-60 mg/kg/day divided into 4-6 hour intervals 2
Administration Considerations
Route of Administration
- Oral suspension is preferred over suppositories due to more consistent absorption and response 3
- For infants and young children, use an appropriate measuring device such as a 3-mL or 5-mL oral syringe for accurate measurement 5
Age-Specific Considerations
- Acetaminophen is the only recommended analgesic for children under 3 months of age 6
- Dosing schedules can be adapted to age-based or weight-based approaches, with weight-based being more accurate 1
Special Populations
Hepatic Impairment
- Reduce doses and extend intervals in children with hepatic impairment to minimize hepatotoxicity risk 7
Renal Impairment
- Standard dosing can generally be used, but monitor for accumulation in severe cases 7
Safety Considerations and Toxicity Prevention
Hepatotoxicity Risk
- Single ingestions of more than 10 times the recommended dose (>140 mg/kg) are potentially toxic 2
- Chronic exposures greater than 140 mg/kg/day for several days carry risk of serious liver toxicity and failure 8, 2
- Overdose can result in liver and kidney failure, particularly with repeated supratherapeutic ingestions 8
Common Dosing Errors
- In community practice, only 61% of parents administer appropriate doses, with 12% giving overdoses (≥20 mg/kg) and 27% giving underdoses (<10 mg/kg) 4
- Proper parent education is essential to prevent inadequate or excessive administration 4
Combination Products
- Exercise caution when using combination opioid-acetaminophen products to prevent excess acetaminophen dosing 9
- The FDA has limited acetaminophen content in prescription combination products to 325 mg per dosage unit 8
Clinical Efficacy
Antipyretic Effect
- Plasma concentrations of 4-18 mg/L are appropriate for antipyretic effect 3
- More than 10 mg/kg is required to maintain temperature 1.5°C below baseline for 6 hours 3
- Half-life is 1-3.5 hours in children 3
Analgesic Effect
- Effective for mild to moderate pain in children 2, 6
- Provides significant additive analgesic effect when combined with opiates for severe pain 2
- Equivalent efficacy to aspirin at the same dose (10-15 mg/kg) 3
Second-Line Options
- If acetaminophen is ineffective for fever management, ibuprofen may be considered as second-line treatment 5