What is the appropriate acetaminophen (paracetamol) suppository dose for a 4‑year‑old child weighing 38 lb?

Acetaminophen Suppository Dosing for a 4-Year-Old Weighing 38 Pounds

For a 4-year-old child weighing 38 pounds (17.3 kg), administer 173–260 mg of acetaminophen per dose rectally every 4–6 hours, not exceeding 5 doses in 24 hours or a maximum daily dose of 1,038 mg. 1

Weight-Based Calculation

• The standard acetaminophen dose is 10–15 mg/kg per dose. 1
• For a 38-pound child (17.3 kg):
  • Lower end: 10 mg/kg × 17.3 kg = 173 mg per dose
  • Upper end: 15 mg/kg × 17.3 kg = 260 mg per dose 1, 2
• Maximum daily dose: 60 mg/kg/day = 1,038 mg/day (not to exceed 5 doses in 24 hours). 1

Practical Suppository Dosing

• Most pediatric acetaminophen suppositories come in 80 mg, 120 mg, 160 mg, or 325 mg strengths.
• For this child, use a 160 mg suppository (falls within the 173–260 mg range) or two 80 mg suppositories (160 mg total). 3
• Alternatively, a 200 mg suppository (if available) would be appropriate and closer to the mid-range dose of 216 mg. 4

Critical Caveats About Rectal Administration

• Rectal acetaminophen has erratic and unpredictable absorption compared to oral formulations. 1
• Oral syrup is absorbed more rapidly and provides a more consistent response than suppositories. 1
• Use suppositories only when the oral route is not feasible (e.g., active vomiting, perioperative setting, or child refusal). 1
• Because of erratic absorption, some children may receive inadequate analgesia while others risk drug accumulation with repeated dosing. 1

Dosing Interval and Frequency

• Administer every 4–6 hours as needed. 1, 2
• Do not exceed 5 doses in 24 hours to prevent hepatotoxicity. 1
• The maximum daily dose of 60 mg/kg/day (1,038 mg for this child) must never be exceeded. 1

Special Considerations for Dose Reduction

• If the child has chronic malnutrition, has fasted for more than 8 hours, or is on cytochrome P450-inducing medications (e.g., isoniazid), reduce the dose to 10 mg/kg (173 mg per dose). 1
• For children with known liver disease, also use the reduced 10 mg/kg dose, though acetaminophen remains safer than NSAIDs in this population. 1

Common Pitfalls to Avoid

• Do not use acetaminophen suppositories as first-line therapy when oral administration is possible, as absorption variability may lead to treatment failure or toxicity. 1
• Avoid chronic overdosing: Exposures greater than 140 mg/kg/day for several days carry a risk of serious hepatotoxicity. 2
• Single ingestions of more than 10 times the recommended dose (>1,730 mg for this child) are potentially toxic and require immediate medical evaluation. 2