How the doses are worked out

  • Weight-based dose: dose (mg) = weight (kg) × dose per kg (mg/kg). The dose is never allowed to go above the maximum single dose you enter, which for older or heavier children is usually the adult dose.
  • Liquid volume: volume (mL) = dose (mg) ÷ strength (mg per mL). A bottle labelled "120 mg/5 mL" contains 24 mg in each mL.
  • Daily total: single dose × number of doses a day, checked against the daily maximum.

Reference doses used for the presets

Medicine Dose Interval Maximum Common liquids
Paracetamol 15 mg/kg Every 4 to 6 hours, no more than 4 doses in 24 hours 1 g per dose; 60 mg/kg (and 4 g) a day 120 mg/5 mL, 250 mg/5 mL
Ibuprofen 10 mg/kg Every 8 hours (3 times a day) with food 400 mg per dose; 30 mg/kg a day 100 mg/5 mL
Amoxicillin (pneumonia) 40 mg/kg Twice a day for 5 days 1 g per dose 125 mg/5 mL, 250 mg/5 mL

Doses differ between countries, conditions and formulary editions. These presets are a starting point for checking, not a prescription.

Giving liquid medicine to a child safely

  • Use the oral syringe or measuring spoon that comes with the medicine, never a kitchen spoon.
  • Check the strength on the bottle: the same medicine comes in different strengths.
  • Write down the time of each dose so it is not repeated too soon, and check other medicines (for example cold remedies) do not contain the same ingredient.
  • Ibuprofen is not for babies under 3 months or under 5 kg, or for children who are dehydrated. Ask before giving paracetamol to a baby under 3 months.
For students & clinicians (technical detail)
  • Weight estimate (APLS): 0 to 12 months: (0.5 × age in months) + 4; 1 to 5 years: (2 × age) + 8; 6 to 12 years: (3 × age) + 7.
  • Holliday–Segar maintenance fluid: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg, 20 mL/kg/day above 20 kg (4-2-1 mL/kg/h). Many units now give 2/3 of this as isotonic fluid; check local policy.
  • Body surface area (Mosteller): BSA (m²) = √(height cm × weight kg ÷ 3600).
  • Ideal body weight (Devine): male 50 kg, female 45.5 kg, plus 2.3 kg for each inch over 5 feet.
  • Adjusted body weight: IBW + 0.4 × (actual weight − IBW), often used when actual weight is more than 120% of IBW (for example aminoglycosides).
  • Cockcroft–Gault creatinine clearance: (140 − age) × weight × (0.85 if female) ÷ (0.814 × creatinine in µmol/L), in mL/min. Many drug labels use this, not eGFR, for renal dose bands.
  • Infusion rate: mL/h = dose per hour ÷ concentration. Drops/min = mL/h × drop factor ÷ 60.