Cotrimoxazole Pediatric Dose Calculator
Weight-based pediatric dosing for Co-trimoxazole (TMP–SMX). Also known as Septra, Bactrim, Oriprim. Built for busy OPDs and emergency settings — free, offline after first load.
Typical pediatric dosing
UTI / chest (by TMP): 4 mg/kg BD — max 160 mg/dose — 5–7 days — Dose on trimethoprim. Syrup 5 mL ≈ 40 mg TMP.; PCP prophylaxis: 2.5 mg/kg OD (3 days/week) — max 160 mg/dose — As advised
Syrup strengths: 240 mg/5mL
For a typical 5-year-old (~18 kg), one dose is about 72 mg — use the calculator for exact syrup mL by strength.
Complete Co-trimoxazole (TMP–SMX) details
- Age range
- ≥6 weeks – adult
- Min age
- 1.5 months
- Pregnancy
- Category D — Avoid 1st trimester and near term when possible.
- Clinical notes
- Avoid G6PD deficiency and sulpha allergy.
- Also known as
- septra, bactrim, tmp-smx, co-trimoxazole
Indications & regimens
- UTI / chest (by TMP): 4 mg/kg BD — max 160 mg/dose — 5–7 days — Dose on trimethoprim. Syrup 5 mL ≈ 40 mg TMP.
- PCP prophylaxis: 2.5 mg/kg OD (3 days/week) — max 160 mg/dose — As advised
Formulations
- Oral syrup / suspension: 240 mg/5mL (40 TMP + 200 SMX / 5 mL)
- Tablets: 480 mg (80+400), 960 mg (160+800 Forte)
Adult dosing
960 mg; BD; max single 960 mg
Contraindications & cautions
See product insert and local protocol for contraindications and cautions.
Medical trust & authorship (EEAT)
Who owns and developed PediaRx? Dr. Shounak Pal, MBBS — Founder, clinical author, and sole developer of PediaRx. The clinical database was authored for the developer’s own practice and peer-tested with clinical colleagues; it is not a third-party “review-only” widget.
Qualifications: Practising physician (MBBS). Profile: https://www.shounakpal.com.
References: BNFc, IAP Drug Formulary, WHO guidance, NNF neonatal schedules (where applicable), and product inserts. Primary jurisdiction: India (IN). Useful globally — always verify against local formularies.
Last drug-record review: 2026-07 (formulary DB v4.0). Live updates sync from db.pediarx.com; corrections are issued via formulary version bumps.
Privacy: No patient identifiers collected. Weight/age stay on-device. Intended for clinicians, not patient self-medication.
How to report an error: [email protected] · Disclaimer · Privacy
Common questions
What is the pediatric dose of Co-trimoxazole (TMP–SMX)?
UTI / chest (by TMP): 4 mg/kg BD — max 160 mg/dose — 5–7 days — Dose on trimethoprim. Syrup 5 mL ≈ 40 mg TMP.; PCP prophylaxis: 2.5 mg/kg OD (3 days/week) — max 160 mg/dose — As advised Always verify against current national guidelines and the product label.
How do I calculate Co-trimoxazole (TMP–SMX) syrup dose for a child?
Enter the child's age and weight in the calculator on this page (right column on desktop; above the article on mobile). PediaRx shows mg per dose, syrup mL by strength, tablet fractions, and IV volume when available — using the live formulary from db.pediarx.com. Brand names include Septra, Bactrim, Oriprim.
Who built and maintains the Co-trimoxazole (TMP–SMX) dosing data in PediaRx?
PediaRx was built and clinically authored by Dr. Shounak Pal, MBBS — a practising physician — for personal clinical use and peer-tested with colleagues. It is not a third-party review of someone else's calculator.
What references support these doses?
Doses are curated from BNFc, IAP Drug Formulary, WHO guidance, and NNF schedules where applicable. India (IN) is the primary formulary region; always confirm against your local protocol and product insert.
Does PediaRx collect patient information?
No. Age, weight, and sex stay on your device. Calculations run locally. Anonymous analytics (page views) may be collected; no clinical inputs are transmitted.
Is PediaRx for clinicians or patients?
PediaRx is a clinical reference for qualified healthcare professionals (GDMOs, paediatricians, medical officers, family physicians). It is not intended as a consumer self-medication tool.
Is PediaRx free?
Yes. Free clinical reference — no ads, no subscriptions, no accounts. Works offline after first load.
What is the pregnancy category for Co-trimoxazole (TMP–SMX)?
Category D. Avoid 1st trimester and near term when possible.
Clinical disclaimer: Reference tool for qualified professionals only. Verify every dose against IAP/NNF/BNFc/product insert before prescribing. Clinical aid only. Verify every dose with IAP/NNF/BNFc/product insert/local protocol before prescribing.
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