Acetaminophen Dosing for a 6-Month-Old Infant
For a 6-month-old infant, give acetaminophen 10-15 mg/kg per dose every 4-6 hours, not exceeding 60 mg/kg per day or 5 doses in 24 hours. 1
Weight-Based Dosing Approach
- Use 15 mg/kg per dose for infants under 10 kg to ensure adequate therapeutic effect, as this is the dose specifically recommended by the American Academy of Pediatrics for young infants 1
- Administer every 4-6 hours as needed, with a minimum 4-hour interval between doses 1
- The maximum daily dose must never exceed 60 mg/kg per day 1
Formulation Selection
- Oral syrup is strongly preferred over rectal suppositories because it provides more rapid absorption and consistent therapeutic response 1
- Rectal acetaminophen has erratic absorption and should only be considered if the infant is actively vomiting 1
- Some infants may receive inadequate analgesia with rectal formulations while others risk drug accumulation with repeated dosing 1
Common Dosing Pitfalls to Avoid
- Age-based dosing leads to errors in up to 30% of cases—always calculate the dose based on the infant's actual weight 2
- Doses of 10 mg/kg may not achieve adequate plasma concentrations (10-20 μg/mL) needed for antipyresis, which is why 15 mg/kg is preferred for young infants 2
- Parents frequently underdose (27% give less than 10 mg/kg) or overdose (12% give 20 mg/kg or more), emphasizing the need for clear weight-based instructions 3
Special Circumstances
- For post-vaccination fever prevention, acetaminophen 15 mg/kg can be given at the time of vaccination and every 4 hours for 24 hours 4, 1
- For infants with a history of febrile seizures, the same prophylactic dosing (15 mg/kg every 4 hours for 24 hours) can reduce fever-related discomfort, though it does not prevent seizure recurrence 1
- At 6 months of age, acetaminophen remains the only recommended analgesic, as ibuprofen is generally not recommended for infants under 6 months 1
Practical Calculation Example
- For a 7 kg infant: 7 kg × 15 mg/kg = 105 mg per dose
- For an 8 kg infant: 8 kg × 15 mg/kg = 120 mg per dose
- For a 9 kg infant: 9 kg × 15 mg/kg = 135 mg per dose