Pediatric Weight-Based Drug Dosing
Pediatric drug dosing is weight-based because children have significantly different pharmacokinetics from adults — higher metabolic rates, different volume of distribution, and immature hepatic and renal function that evolves throughout childhood. Using adult doses in children risks both under-dosing (treatment failure) and overdose (toxicity).
Key Principles
- Always use current weight — estimated or parent-reported weights introduce significant error; weigh the child whenever possible.
- Apply maximum dose caps — once a child reaches approximately 40 kg or the adult dose threshold, whichever is lower, cap at the adult dose. This calculator supports entering a maximum dose.
- Double-check concentration — liquid medicines come in varying concentrations (e.g. paracetamol 120 mg/5 mL for infants vs 250 mg/5 mL for older children). Always confirm the concentration on the label.
- Round sensibly — round to the nearest 0.1 mL for volumes; round to a measurable dose that can be reliably administered with available equipment.
Common Pediatric Drug Doses Reference
| Drug | Dose | Frequency | Max Single Dose |
|---|---|---|---|
| Paracetamol (oral) | 15 mg/kg | QDS | 1,000 mg |
| Ibuprofen (oral) | 5–10 mg/kg | TDS | 400 mg |
| Amoxicillin | 25 mg/kg/day | TDS (÷3) | 500 mg/dose |
| Co-amoxiclav | 25 mg/kg/day (amoxicillin) | TDS | 500 mg/dose |
| Cetirizine (>6yr) | 5 mg/day | OD | 10 mg/day |
| Dexamethasone (croup) | 0.15 mg/kg single dose | Once | 10 mg |
| Salbutamol (oral) | 0.1–0.2 mg/kg | TDS–QDS | 4 mg |
Related Tools on MediCalc Pro
For BSA-based dosing (oncology), see BSA Calculator. For adult weight-based dosing, see Weight-Based Dose Calculator. For pediatric fluid requirements (Holliday-Segar), see Pediatric Fluid Requirement. For pediatric growth assessment, see Growth Chart Percentile. For IV drug infusion rates, see IV Drip Rate Calculator. For drug concentration conversions, see Drug Concentration Converter.
References
- Paediatric Formulary Committee. BNF for Children 2023–2024. BMJ Group, 2023.
- Taketomo CK, et al. Pediatric & Neonatal Dosage Handbook. 30th ed. Lexicomp, 2023.
- World Health Organization. WHO Model Formulary for Children. WHO Press, 2010.
⚠️ Safety Warning: Always verify all pediatric drug doses against a current formulary (BNFc, Lexicomp Pediatric) before prescribing or administering. Pediatric dosing errors are among the most common and serious medication errors. This calculator is a calculation aid only — it does not replace clinical judgement or formulary verification.