Flucloxacillin Pediatric Dose Calculator
Weight-based flucloxacillin dosing for children — 12.5–25 mg/kg/dose · every 6 hours, 1 hour before food · max 500 mg/dose. Enter age and weight for the dose in mg and syrup mL, capsules or injection volume.
Pediatric dosing
Staphylococcal skin / soft-tissue infection (oral)
Severe staphylococcal infection — IV (hospital) Hospital
Flucloxacillin dose chart by age and weight
Staphylococcal skin / soft-tissue infection (oral). Weights are WHO/IAP reference medians for age — always dose on the measured weight.
| Age | Weight | Dose (mg) | Suspension 125 mg/5 mL | Frequency |
|---|---|---|---|---|
| 1 month | 4.3 kg | 53.8 mg | 2.2 mL | Every 6 hours, 1 hour before food |
| 3 months | 6.1 kg | 76.3 mg | 3.1 mL | Every 6 hours, 1 hour before food |
| 6 months | 7.6 kg | 95 mg | 3.8 mL | Every 6 hours, 1 hour before food |
| 9 months | 8.6 kg | 107.5 mg | 4.3 mL | Every 6 hours, 1 hour before food |
| 1 year | 9.3 kg | 116.3 mg | 4.7 mL | Every 6 hours, 1 hour before food |
| 18 months | 10.6 kg | 132.5 mg | 5.3 mL | Every 6 hours, 1 hour before food |
| 2 years | 11.8 kg | 147.5 mg | 5.9 mL | Every 6 hours, 1 hour before food |
| 3 years | 14.1 kg | 176.3 mg | 7.1 mL | Every 6 hours, 1 hour before food |
| 4 years | 16.2 kg | 202.5 mg | 8.1 mL | Every 6 hours, 1 hour before food |
| 5 years | 17.5 kg | 218.8 mg | 8.8 mL | Every 6 hours, 1 hour before food |
| 6 years | 19 kg | 237.5 mg | 9.5 mL | Every 6 hours, 1 hour before food |
| 8 years | 24.4 kg | 305 mg | 12 mL | Every 6 hours, 1 hour before food |
| 10 years | 31.1 kg | 388.8 mg | 15.5 mL | Every 6 hours, 1 hour before food |
| 12 years | 39.4 kg | 492.5 mg | 19.5 mL | Every 6 hours, 1 hour before food |
Strengths in the calculator
- Suspension 125 mg/5 mL (Oral)
- Capsule 250 mg (Oral)
- Capsule 500 mg (Oral)
- 500 mg vial (reconstitute as per product insert) (Intravenous / Intramuscular)
- 1 g vial (reconstitute as per product insert) (Intravenous)
Different strength on your bottle? Use “Different strength on the bottle?” under the result.
Safety
Contraindications and cautions
- Penicillin allergy.
- History of flucloxacillin-associated jaundice or hepatic dysfunction.
Pregnancy and breastfeeding
Legacy FDA category B. Not known to be harmful.
Compatible with breastfeeding.
Clinical notes
Absorption falls with food: give on an empty stomach. Cloxacillin is a closely related alternative where flucloxacillin is unavailable.
Adult and adolescent (≥40 kg) dose
250 mg–1 g — Every 6 hours, 1 hour before food (max 1 g per dose, 4 g per day).
Other names and brands
Also known as Floxacillin.
- UK: Floxapen
Brand examples only — products and strengths vary by country. Always check the label.
Frequently asked questions
What is the flucloxacillin dose for children?
Staphylococcal skin / soft-tissue infection (oral): 12.5–25 mg/kg/dose · every 6 hours, 1 hour before food · max 500 mg/dose. Usual duration: 5–7 days. Always use the child's measured weight and check the strength on the bottle.
How many mL of suspension 125 mg/5 mL for an 11.8 kg child?
For staphylococcal skin / soft-tissue infection (oral), an 11.8 kg child (about 2 years) needs 147.5 mg per dose — 5.9 mL of Suspension 125 mg/5 mL, every 6 hours, 1 hour before food. Recalculate with the child's actual weight.
From what age can flucloxacillin be given?
Age range in PediaRx: 1 month – adult. The calculator does not calculate a dose below 1 month. Each indication can have its own age and weight limits, shown with its regimen.
Is flucloxacillin safe in pregnancy?
Legacy FDA category B. Not known to be harmful.
Sources and editorial process
- BNF for Children — Flucloxacillin — NICE / BMJ Group / Royal Pharmaceutical Society
Dosing data last updated 2026-09-27. PediaRx is built and maintained by Dr. Shounak Pal, MBBS (Medical Officer, Government of West Bengal, India — founder and developer of PediaRx). Every regimen is encoded with explicit units, maximum doses and age/weight limits and is checked by automated tests before publication. Report an error: hello@pediarx.com.
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Clinical disclaimer: reference tool for qualified health professionals. Verify every dose against current guidance and the product label before prescribing.
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