Pediatric Paracetamol Calculator

The Pediatric Paracetamol Calculator provides comprehensive dosing for paracetamol (acetaminophen) across all routes of administration including oral, rectal, and intravenous, using international dosing guidelines. Paracetamol is the most frequently used analgesic and antipyretic worldwide for children, available in virtually every country under numerous brand names including Calpol, Panadol, Tylenol, and many generic preparations.

Dosing varies by route of administration due to differences in bioavailability. Oral paracetamol has approximately 60-90% bioavailability and is dosed at 15 mg/kg per dose every 4-6 hours. Rectal paracetamol has lower and more variable bioavailability (approximately 30-40%) and is therefore dosed higher at 15-20 mg/kg per dose every 6-8 hours. Intravenous paracetamol achieves 100% bioavailability and is dosed at 15 mg/kg for children over 10 kg and 7.5 mg/kg for neonates and infants under 10 kg.

The maximum daily dose is critical for safety. For children weighing more than 10 kg, the maximum is 60 mg/kg/day or 4,000 mg/day (whichever is less) for oral and rectal routes. For intravenous administration in infants under 10 kg, the maximum daily dose is reduced to 30 mg/kg/day. These limits are designed to prevent hepatotoxicity, which is the most serious adverse effect of paracetamol overdose.

Oral paracetamol is available in multiple concentrations internationally. In the UK and Europe, the standard pediatric suspension is 120 mg per 5 mL (24 mg/mL). The six-plus formulation contains 250 mg per 5 mL. In the US and some other markets, the standard is 160 mg per 5 mL (32 mg/mL). This calculator uses the 120 mg/5 mL concentration common in international practice; adjust volume calculations accordingly if using a different concentration.

Rectal administration is used when oral dosing is not feasible, such as in vomiting children, perioperative settings, or when NPO (nil per os) status is required. Rectal suppositories are available in various strengths (60, 80, 120, 125, 240, 250, 325, and 500 mg). The higher rectal dose compensates for lower bioavailability, but absorption is more variable and onset is slower than oral dosing.

Intravenous paracetamol (brand name Perfalgan or Ofirmev) is used in hospital settings for perioperative pain management and when other routes are unavailable. It provides rapid and reliable drug levels. For infants and neonates weighing 10 kg or less, the reduced dose of 7.5 mg/kg reflects their immature hepatic metabolism and reduced glutathione stores, which increase susceptibility to hepatotoxicity.

This calculator provides route-specific dosing with appropriate safety limits, supporting accurate paracetamol administration across clinical scenarios. All doses should be verified against current formulary guidelines, and hepatic function should be considered in children with liver disease, malnutrition, or those receiving enzyme-inducing medications.