Cephalexin Pediatric Dose Calculator

Weight-based cephalexin dosing for children — 6.25–25 mg/kg/dose · every 6 hours · max 500 mg/dose. Enter age and weight for the dose in mg and syrup mL or capsules.

Category: AntibioticAges: 1 month – adultUpdated: 2026-09-27For: clinicians

Pediatric dosing

Skin / soft-tissue infection, UTI

6.25–25 mg/kg/dose · every 6 hours · max 500 mg/dose

Duration: 5–10 days · 50 mg/kg/day. Severe infection: up to 25 mg/kg every 6 hours (max 1 g per dose).

Streptococcal pharyngitis (non-anaphylactic penicillin allergy)

20 mg/kg/dose · every 12 hours · max 500 mg/dose

Duration: 10 days

Cephalexin dose chart by age and weight

Skin / soft-tissue infection, UTI. Weights are WHO/IAP reference medians for age — always dose on the measured weight.

Computed with the PediaRx dose engine from the regimen above; caps and age limits applied.
Age	Weight	Dose (mg)	Suspension 125 mg/5 mL	Suspension 250 mg/5 mL	Frequency
1 month	4.3 kg	53.8 mg	2.2 mL	1.1 mL	Every 6 hours
3 months	6.1 kg	76.3 mg	3.1 mL	1.5 mL	Every 6 hours
6 months	7.6 kg	95 mg	3.8 mL	1.9 mL	Every 6 hours
9 months	8.6 kg	107.5 mg	4.3 mL	2.2 mL	Every 6 hours
1 year	9.3 kg	116.3 mg	4.7 mL	2.3 mL	Every 6 hours
18 months	10.6 kg	132.5 mg	5.3 mL	2.7 mL	Every 6 hours
2 years	11.8 kg	147.5 mg	5.9 mL	3 mL	Every 6 hours
3 years	14.1 kg	176.3 mg	7.1 mL	3.5 mL	Every 6 hours
4 years	16.2 kg	202.5 mg	8.1 mL	4.1 mL	Every 6 hours
5 years	17.5 kg	218.8 mg	8.8 mL	4.4 mL	Every 6 hours
6 years	19 kg	237.5 mg	9.5 mL	4.8 mL	Every 6 hours
8 years	24.4 kg	305 mg	12 mL	6.1 mL	Every 6 hours
10 years	31.1 kg	388.8 mg	15.5 mL	7.8 mL	Every 6 hours
12 years	39.4 kg	492.5 mg	19.5 mL	9.9 mL	Every 6 hours

Strengths in the calculator

Suspension 125 mg/5 mL (Oral)
Suspension 250 mg/5 mL (Oral)
Capsule 250 mg (Oral)
Capsule 500 mg (Oral)

Different strength on your bottle? Use “Different strength on the bottle?” under the result.

Safety

Contraindications and cautions

Cephalosporin allergy; avoid after anaphylaxis to penicillin.

Pregnancy and breastfeeding

Legacy FDA category B. Widely used in pregnancy; no evidence of harm.

Compatible with breastfeeding.

Clinical notes

First-generation cephalosporin — good for impetigo, cellulitis and staphylococcal skin infection.

Adult and adolescent (≥40 kg) dose

250–500 mg — Every 6 hours (max 500 mg per dose, 2 g per day).

Severe infection: up to 1 g every 6 hours.

Other names and brands

Also known as Cefalexin.

India: Phexin, Sporidex
USA: Keflex

Brand examples only — products and strengths vary by country. Always check the label.

Frequently asked questions

What is the cephalexin dose for children?

Skin / soft-tissue infection, UTI: 6.25–25 mg/kg/dose · every 6 hours · max 500 mg/dose. Usual duration: 5–10 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 skin / soft-tissue infection, UTI, 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. Recalculate with the child's actual weight.

From what age can cephalexin 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 cephalexin safe in pregnancy?

Legacy FDA category B. Widely used in pregnancy; no evidence of harm.

Sources and editorial process

BNF for Children — Cefalexin — NICE / BMJ Group / Royal Pharmaceutical Society
Practice guidelines for skin and soft tissue infections (Stevens et al., Clin Infect Dis 2014) — IDSA
Clinical practice guideline for group A streptococcal pharyngitis (Shulman et al., Clin Infect Dis 2012) — IDSA

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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