Ceftriaxone Dose Calculator
India · Paediatric mg/kg · Neonatal · Adult · Meningitis · Sepsis · Typhoid · CAP · UTI · Monocef · Oframax
Ceftriaxone Dose Calculator
✓ Streptococcus pneumoniae (meningitis, CAP)
✓ Neisseria meningitidis / gonorrhoeae
✓ H. influenzae
✓ Salmonella typhi (typhoid)
✓ E. coli, Klebsiella (UTI, sepsis)
✗ Pseudomonas (use ceftazidime)
✗ MRSA · Enterococcus · Anaerobes
✗ Listeria (neonatal meningitis — add ampicillin)
Ceftriaxone Dosing Reference — Paediatric, Neonatal & Adult
| Indication | Paediatric dose | Adult dose | Frequency | Duration |
|---|---|---|---|---|
| Bacterial meningitis | 100 mg/kg/day (max 4g) | 2g every 12 hours | BD (q12h) for meningitis | 7–10d (pneumococcal); 7d (meningococcal) |
| Sepsis / severe infection | 50–80 mg/kg/day (max 4g) | 2g once daily | OD or BD | 7–14 days (guided by clinical response) |
| Typhoid — severe / IV | 75 mg/kg/day (max 2.5g) | 2–3g once daily | Once daily | 10–14 days |
| Community pneumonia (CAP) | 50 mg/kg/day (max 2g) | 1–2g once daily | Once daily | 5–7 days |
| Complicated UTI | 50 mg/kg/day (max 2g) | 1–2g once daily | Once daily | 10–14 days |
| Gonorrhoea (single dose) | 125–250 mg IM (single) | 500mg IM (single) — WHO 2016 | Single dose | Single dose |
| Surgical prophylaxis | 50 mg/kg (max 2g) | 1–2g | Single dose 30–60 min pre-incision | Single dose |
| Neonatal sepsis (term) | 50 mg/kg OD | — | Once daily | 10–14 days |
| Neonatal meningitis | 50 mg/kg BD | — | Every 12 hours | 21 days |
Ceftriaxone — Clinical Guide India
Ceftriaxone is a third-generation cephalosporin and one of the most widely used IV/IM antibiotics in Indian hospitals. It provides broad Gram-negative and Gram-positive coverage with excellent tissue penetration, including the central nervous system — making it first-line for bacterial meningitis in India. Its long half-life (6–9 hours) allows once-daily dosing for most indications, reducing nursing workload and improving compliance. Available as Monocef and Oframax in 250mg, 500mg, 1g, and 2g vials.
Meningitis — the highest-dose indication
Bacterial meningitis requires the highest ceftriaxone doses because adequate CSF drug levels are essential and the blood-brain barrier limits CNS penetration. Paediatric dose: 100 mg/kg/day — given as 50 mg/kg every 12 hours. Adult dose: 2g every 12 hours. Always give dexamethasone 0.15 mg/kg IV before or with the first antibiotic dose in suspected bacterial meningitis — this significantly reduces hearing loss (particularly in H. influenzae meningitis) and meningeal inflammation. If Listeria monocytogenes is possible (neonates, immunocompromised, elderly), add ampicillin — ceftriaxone does not cover Listeria.
Critical neonatal caution — calcium interaction
Ceftriaxone is contraindicated in neonates receiving calcium-containing IV fluids simultaneously — including total parenteral nutrition (TPN) and Ringer's lactate. Ceftriaxone-calcium precipitates form in the lungs and kidneys and have caused neonatal deaths. Use cefotaxime instead in neonates requiring concurrent calcium administration. This is a critical patient safety issue — the interaction is not relevant in older children and adults at the doses used clinically.
IM reconstitution — reducing injection pain
For IM ceftriaxone, the vial should be reconstituted with 1% lignocaine (lidocaine) solution (not water) to significantly reduce injection pain. For a 1g vial: add 3.5ml of 1% lignocaine. For a 500mg vial: add 2ml of 1% lignocaine. Inject deep IM into the upper outer gluteal quadrant. Never exceed 1g per injection site — if 2g is needed IM, give 1g at each gluteal site. Never reconstitute with lignocaine for IV use.
Typhoid — when to use ceftriaxone vs azithromycin
For uncomplicated typhoid in ambulatory patients, azithromycin oral remains the first-line agent in India (see Azithromycin page). Ceftriaxone IV is used when: the patient cannot take oral medications (vomiting), severe typhoid with complications (intestinal perforation, hepatitis, encephalopathy), failed oral azithromycin, or when confirmed ceftriaxone-sensitive isolate on culture. Duration: 10–14 days IV for severe cases.