Tylenol Dosage for 11-Pound Baby
For an 11-pound (5 kg) baby, give 50-75 mg of acetaminophen (Tylenol) every 4-6 hours as needed, using the 15 mg/kg dose which is most effective for infants. 1
Weight-Based Dosing Calculation
- An 11-pound baby weighs 5 kg (11 lbs ÷ 2.2 = 5 kg)
- Standard dosing is 10-15 mg/kg per dose 1
- For a 5 kg infant:
- 10 mg/kg = 50 mg per dose
- 15 mg/kg = 75 mg per dose 1
The 15 mg/kg dose (75 mg) is preferred for infants under 10 kg, as pharmacokinetic modeling demonstrates that 10 mg/kg doses fail to reach therapeutic plasma concentrations (10-20 μg/mL) needed for effective antipyresis. 2, 3
Practical Administration
- Using infant acetaminophen drops (160 mg/5 mL concentration):
- For 50 mg: give 1.6 mL
- For 75 mg: give 2.3 mL 1
- Dosing interval: Every 4-6 hours as needed 1
- Maximum: 5 doses in 24 hours (never exceed 60 mg/kg per day) 1
Critical Safety Considerations
For infants under 3 months of age, acetaminophen is the only recommended analgesic—ibuprofen should not be used. 1 This 11-pound baby is likely 2-4 months old based on typical growth patterns, making acetaminophen the appropriate choice.
Oral syrup formulation is absorbed more rapidly and provides more consistent response compared to rectal suppositories, which have erratic absorption. 1, 4 Use oral administration whenever possible.
Parents must ensure regular feeding to reduce hypoglycemia risk. If the infant becomes unwell and feeding is reduced, stop acetaminophen until normal feeding resumes. 5
Common Dosing Errors to Avoid
Up to 62% of parents give inaccurate acetaminophen doses, with infants under 1 year at highest risk for dosing errors. 6 The most common mistake is using age-based rather than weight-based dosing, which leads to underdosing in smaller infants. 2, 6
Weight-based dosing significantly reduces dosing errors compared to age-based recommendations. 6 Always calculate the dose based on the infant's actual weight in kilograms, not age or manufacturer's age-based charts.
Never use adult formulations or concentrations for infants, as this dramatically increases the risk of calculation errors and potential overdose. 1