Amoxicillin Dose Calculator
India · Paediatric & Adult · mg/kg Weight-Based Dosing · Augmentin · Amoxil · Mox
Amoxicillin Dose Calculator
Amoxicillin Dosing Reference Table — India
| Indication | Dose | Frequency | Duration | Notes |
|---|---|---|---|---|
| Tonsillitis / pharyngitis (child) | 40 mg/kg/day | TDS (every 8h) | 7–10 days | Max 1.5g/day |
| Otitis media (child) | 80–90 mg/kg/day | BD or TDS | 5–10 days | High dose for resistant S. pneumoniae |
| URTI / mild chest (adult) | 500 mg | TDS | 5–7 days | Standard adult dose |
| CAP — community pneumonia (adult) | 1g | TDS | 5–7 days | NICE/BTS guidelines |
| UTI — uncomplicated | 500 mg | TDS | 3–7 days | Check local resistance patterns |
| H. pylori (with clarithromycin + PPI) | 1g | BD | 7–14 days | Part of triple therapy |
| Augmentin 625 (adult) | 625 mg (500+125) | TDS | 5–7 days | Animal bites, diabetic foot, sinusitis |
| IV — severe infection (adult) | 1–2g | TDS–QDS | As directed | Hospital setting, IV access |
| Neonate (<1 month) | 30 mg/kg/dose | BD | As directed | Specialist supervision required |
TDS = three times daily · BD = twice daily · QDS = four times daily. Always use weight-based dosing for children under 12 years.
About Amoxicillin — Clinical Guide for Indian Doctors
Amoxicillin is a broad-spectrum aminopenicillin antibiotic and one of the most widely prescribed drugs in India. It is bactericidal, acting by inhibiting bacterial cell wall synthesis through binding to penicillin-binding proteins (PBPs). It covers most Gram-positive cocci (Streptococcus, Enterococcus) and several Gram-negative organisms (Haemophilus influenzae, E. coli, Salmonella). It does not cover beta-lactamase-producing bacteria, which is where Augmentin (amoxicillin-clavulanate) becomes relevant.
In the Indian context, amoxicillin remains a cornerstone drug for primary care — used in community-acquired respiratory tract infections, otitis media, streptococcal tonsillitis, uncomplicated UTIs, H. pylori eradication, and dental infections. It is on the WHO Essential Medicines List and is available in multiple affordable formulations across India, including the widely recognised brands Novamox, Mox, and Augmentin.
Paediatric dosing — what Indian doctors need to know
Weight-based dosing is essential for children — age-based estimates can lead to significant under- or over-dosing. The standard paediatric dose is 25–50 mg/kg/day divided into three doses (every 8 hours). For high-priority infections such as otitis media (where Streptococcus pneumoniae resistance is increasing in India), the IAP recommends high-dose amoxicillin at 80–90 mg/kg/day. This calculator supports both standard and high-dose regimens depending on the indication selected.
For the syrup formulations most used in Indian paediatric practice — Novamox 125mg/5ml and Amoxil 250mg/5ml — the calculator outputs the exact volume in millilitres, reducing the risk of dispensing errors. Note that 125mg/5ml and 250mg/5ml have very different concentrations; always check the label before dispensing.
Augmentin (Amoxicillin-Clavulanate) dosing
Augmentin adds clavulanate to amoxicillin, protecting it from beta-lactamase-producing organisms. It is the drug of choice for animal bites, sinusitis that has failed plain amoxicillin, diabetic foot infections (mild), aspiration pneumonia, and secondary bacterial infections of the skin. In India, the most common adult formulations are Augmentin 625mg (500mg amoxicillin + 125mg clavulanate, given TDS) and Augmentin 1g (875mg + 125mg, given BD). The dose calculation in this tool is based on the amoxicillin component.
Resistance patterns in India
Beta-lactamase production is widespread among common Indian pathogens — particularly H. influenzae, E. coli, and Klebsiella. Plain amoxicillin is therefore not appropriate for urinary tract infections without local sensitivity data, and is not used for Klebsiella, MRSA, or Pseudomonas infections. For Salmonella typhi (typhoid), significant amoxicillin resistance has been documented in India, and it is no longer recommended as empirical treatment for typhoid fever — azithromycin or ceftriaxone are the current first-line options per NVBDCP and WHO guidelines.
Renal dose adjustment
Amoxicillin is predominantly renally excreted. For patients with CrCl below 30 mL/min, the dosing interval should be extended rather than the dose reduced. For CrCl 10–30 mL/min: extend to every 12 hours. For CrCl <10 mL/min or dialysis: extend to every 24 hours. High doses (for CAP or severe infections) should be used with caution in renal impairment. Use our Creatinine Clearance Calculator to determine the patient's CrCl first.
Drug interactions
- Warfarin: Amoxicillin can increase INR — monitor closely in patients on warfarin.
- Methotrexate: Penicillins reduce methotrexate renal clearance — risk of methotrexate toxicity.
- Oral contraceptives: Theoretical reduction in efficacy — advise additional contraception during course (debated evidence).
- Allopurinol: Increases risk of amoxicillin-induced skin rash — avoid combination where possible.
- Probenecid: Reduces renal tubular secretion of amoxicillin, increasing plasma levels — can be used deliberately to increase levels in selected infections.