What is the appropriate intramuscular dose of paracetamol for a 20‑kg child?

Intramuscular Paracetamol Dose for 20 kg Child

For a 20 kg child, administer 300 mg of intramuscular paracetamol (15 mg/kg), which can be repeated every 4-6 hours as needed, not exceeding 60 mg/kg per day (1200 mg/day maximum for this child). 1

Weight-Based Dosing Calculation

• The standard pediatric dose of paracetamol is 10-15 mg/kg per dose, with the higher end (15 mg/kg) being more effective for adequate analgesia and antipyresis 1, 2
• For a 20 kg child: 20 kg × 15 mg/kg = 300 mg per dose 1
• The lower dose of 10 mg/kg (200 mg) may be used in children with hepatotoxicity risk factors, but is generally subtherapeutic 1, 2

Dosing Interval and Maximum Daily Dose

• Administer every 4-6 hours as needed for pain or fever 1
• Maximum daily dose: 60 mg/kg/day (1200 mg/day for this 20 kg child) 1, 3
• Do not exceed 5 doses in 24 hours 1

Preparation and Administration Considerations

• Commercial IV/IM paracetamol preparations are typically 10 mg/mL concentration 4
• For 300 mg dose: administer 30 mL of the 10 mg/mL solution 4
• Can be diluted in 0.9% normal saline or 5% dextrose if needed for volume adjustment 4

Clinical Context: When to Use Lower Doses (10 mg/kg)

Reduce to 10 mg/kg (200 mg) in these high-risk situations:

• Chronic malnutrition or fasting >8 hours without adequate caloric intake 1
• Concurrent use of cytochrome P450-inducing medications (e.g., isoniazid) 1
• Pre-existing liver disease (though paracetamol remains safer than NSAIDs in this population) 1

Route Comparison: IM vs Oral

• Oral syrup formulations are absorbed more rapidly and provide more consistent response compared to rectal suppositories 1
• IM route should be reserved for situations where oral intake is not possible (active vomiting, perioperative settings, inability to swallow) 1
• The evidence provided does not specifically address IM absorption characteristics, but injectable formulations are generally reliable when oral route is contraindicated 4

Critical Safety Points

• Recent evidence demonstrates that 15 mg/kg dosing is significantly more effective than placebo and at least as effective as NSAIDs, while older studies using ≤10 mg/kg showed inferior efficacy 2
• Chronic overdosing (>140 mg/kg/day for several days) carries risk of serious hepatotoxicity 3
• Single ingestions >10 times the recommended dose are potentially toxic 3
• Monitor for adequate pain/fever relief; if 15 mg/kg dosing is ineffective, consider alternative diagnoses or additional analgesics rather than exceeding maximum daily dose 2