Acetaminophen Suppository Dosing for a 4-Year-Old Weighing 38 Pounds
For a 4-year-old child weighing 38 pounds (17.2 kg), you can administer two 80 mg acetaminophen suppositories (160 mg total) per dose, given every 4-6 hours, with a maximum of 4 doses in 24 hours.
Weight-Based Dose Calculation
The standard acetaminophen dose is 10-15 mg/kg per dose every 4-6 hours, with a maximum daily dose of 60 mg/kg per day 1, 2, 3.
For a 38-pound child (17.2 kg):
- 10 mg/kg dose = 172 mg per dose
- 15 mg/kg dose = 258 mg per dose
- Maximum daily dose = 1,032 mg (60 mg/kg × 17.2 kg) 1
Using 80 mg suppositories, two suppositories (160 mg) falls within the recommended 10-15 mg/kg range (9.3 mg/kg), though it is at the lower end 1, 3.
Practical Dosing Recommendation
Give 2 suppositories (160 mg) every 4-6 hours as needed for fever or pain 1.
Maximum frequency: 4 doses in 24 hours (total 640 mg/day), which remains well below the 1,032 mg maximum daily limit 1, 2.
If inadequate fever or pain control occurs with 160 mg, consider switching to oral formulation at 15 mg/kg (258 mg) for more consistent absorption 1, 4.
Critical Caveats About Rectal Administration
Rectal acetaminophen has erratic absorption compared to oral formulations, meaning some children may receive inadequate analgesia while others risk accumulation with repeated dosing 1.
Oral syrup formulation is absorbed more rapidly and provides more consistent response than suppositories 1, 4.
Rectal administration should be reserved for children who are actively vomiting or unable to take oral medication 1.
Safety Considerations
Never exceed 60 mg/kg per day (1,032 mg for this child) or 5 doses in 24 hours to prevent hepatotoxicity 1, 2.
Verify that no other medications containing acetaminophen (cold/flu remedies, combination products) are being given concurrently—this is the most common cause of inadvertent overdosing 5.
Single ingestions exceeding 140 mg/kg/day for several days carry risk of serious liver toxicity 2.
When to Use Reduced Dosing (10 mg/kg Instead of 15 mg/kg)
If the child has chronic malnutrition or has fasted for more than 8 hours, use 10 mg/kg (172 mg = 2 suppositories) to minimize hepatotoxicity risk 1.
If the child is taking cytochrome P450-inducing medications (e.g., isoniazid), use 10 mg/kg 1.
If the child has known liver disease, use 10 mg/kg, though acetaminophen remains safer than NSAIDs in this population 1.