What is the appropriate pediatric acetaminophen (Tylenol) dose for a child weighing 35.5 kg?

Acetaminophen Dosing for a 35.5 kg Child

For a child weighing 35.5 kg, administer acetaminophen 10-15 mg/kg per dose (355-533 mg) every 4-6 hours as needed, not exceeding 60 mg/kg/day (2,130 mg/day), using pediatric weight-based dosing rather than adult dosing since the child is under the 40 kg threshold. 1, 2, 3

Weight-Based Dosing Calculation

• This child requires pediatric weight-based dosing because they weigh less than 40 kg, which is the critical threshold for transitioning to adult dosing regimens 1, 3
• The recommended dose is 10-15 mg/kg per dose, which calculates to 355-533 mg per dose for this 35.5 kg child 2
• A practical middle-range dose would be approximately 450-500 mg per dose 2

Dosing Interval and Maximum Daily Dose

• Administer every 4-6 hours as needed for pain or fever 1, 2
• Maximum daily dose is 60 mg/kg/day, which equals 2,130 mg/day for this child 2
• This maximum is well below the adult maximum of 3,000-4,000 mg/day, reinforcing that pediatric dosing parameters must be used 1, 4

Formulation and Administration

• Tablets are the most practical formulation for a child of this weight, though liquid formulations with appropriate measuring devices (oral syringes) can be used if preferred 1
• Common tablet strengths include 325 mg and 500 mg; for this child, one 500 mg tablet per dose would be appropriate and falls within the recommended range 1
• If using 325 mg tablets, administering 1.5 tablets (487.5 mg) would provide optimal dosing 1

Critical Safety Considerations

• Counsel caregivers to avoid all other products containing acetaminophen, including over-the-counter cold and flu remedies, to prevent inadvertent overdose 2
• Do not use adult dosing simply because the child may be older—weight is the determining factor, not age 3
• Hepatotoxicity risk is minimal when staying within the 60 mg/kg/day maximum, as toxic levels require plasma concentrations far exceeding therapeutic ranges 5, 6

Common Pitfalls to Avoid

• Do not assume this child can receive adult doses (650-1,000 mg) despite being close to 40 kg—the threshold has not been reached 1, 3
• Ensure calculations use actual body weight (35.5 kg), not ideal body weight or age-based estimates 3
• Verify that pediatric weight-based calculations do not inadvertently exceed standard adult maximum doses when calculating daily totals 3