How the dose is calculated
Ciprofloxacin is generally reserved for specific indications in children (fluoroquinolone use is limited by a cartilage-toxicity signal in animal studies), such as complicated UTI, typhoid fever, or infections with no safer alternative. Dose is calculated in mg/kg/day divided every 12 hours, with the maximum dose depending on the route: oral dosing caps at 750 mg/dose (1500 mg/day), while IV dosing caps lower, at 400 mg/dose (800 mg/day) — IV ciprofloxacin achieves higher bioavailability than the equivalent oral dose, so its ceiling is set lower.
Typical dosing by indication
| Indication | Dose | Frequency | Max (oral) | Max (IV) |
|---|---|---|---|---|
| Standard | 20 mg/kg/day | every 12h (2×/day) | 1500 mg/day (750 mg/dose) | 800 mg/day (400 mg/dose) |
| Severe/complicated | 30 mg/kg/day | every 12h (2×/day) | 1500 mg/day (750 mg/dose) | 800 mg/day (400 mg/dose) |
Clinical use
- Fluoroquinolones like ciprofloxacin are generally reserved in children for infections where no equally effective, safer alternative exists (e.g. complicated UTI, typhoid fever, pseudomonal infection), because of an animal-model signal for cartilage toxicity — this has not been definitively shown to be clinically significant in children at recommended doses, but caution and specialist guidance are still advised.
- Excellent oral bioavailability makes oral ciprofloxacin a reasonable step-down from IV therapy once a patient is clinically stable — note the maximum dose is lower for IV (400 mg/dose, 800 mg/day) than oral (750 mg/dose, 1500 mg/day).
- Absorption is reduced by co-administration with calcium, iron, zinc, or antacids — separate dosing by at least 2 hours.
- Can prolong the QT interval and lower seizure threshold — use caution with relevant comorbidities or interacting medications.
- Topical ciprofloxacin (ear drops for otitis externa/media with perforation, eye drops for bacterial conjunctivitis/keratitis) is a completely different, much lower-dose formulation from the oral/IV systemic dosing on this page — not calculated the same way.
Frequently asked questions
Why is ciprofloxacin not first-line in children?
Animal studies showed a cartilage-toxicity signal with fluoroquinolones, so their use in children is generally reserved for infections (like complicated UTI, typhoid fever, or pseudomonal infection) where no equally effective and safer alternative is available.
What is the maximum ciprofloxacin dose per day?
1500 mg/day (750 mg per dose, twice daily) orally, or 800 mg/day (400 mg per dose, twice daily) IV — the IV maximum is lower because IV ciprofloxacin reaches higher blood levels than the equivalent oral dose.
Can ciprofloxacin be taken with milk or antacids?
It's best avoided — calcium, iron, zinc, and antacids all reduce ciprofloxacin absorption significantly. Separate dosing from these by at least 2 hours.
What is ciprofloxacin used for in typhoid fever?
It's one of several effective oral options for typhoid fever in regions without high fluoroquinolone resistance, dosed by weight and given for the course length specified by local/WHO treatment guidance.
Are ciprofloxacin ear drops different from the oral/IV dose?
Yes — ciprofloxacin ear drops (for otitis externa, or otitis media with a perforated eardrum/grommet) are a topical formulation at a much lower local concentration, dosed as a fixed number of drops rather than by weight. They're a separate product from the oral/IV dosing calculated on this page.
Are ciprofloxacin eye drops different from the oral/IV dose?
Yes — ciprofloxacin eye drops, used for bacterial conjunctivitis and some corneal infections, are a topical ophthalmic formulation dosed as a fixed number of drops per eye at a set interval, not calculated by body weight like the oral/IV regimens above.
What are the side effects of ciprofloxacin?
Common effects include nausea, diarrhoea, and headache. Less common but more serious effects include tendon rupture/tendinopathy (particularly the Achilles tendon), QT prolongation, and (rarely) peripheral neuropathy or CNS effects such as seizures in susceptible patients — these are part of why fluoroquinolones are reserved rather than used as routine first-line therapy.
Does ciprofloxacin need adjusting for kidney function?
Yes — ciprofloxacin is renally cleared, so the dose or dosing interval needs adjustment in significant renal impairment. Check local renal dosing guidance.
References
- World Health Organization. Guidelines for the Management of Typhoid Fever.
- American Academy of Pediatrics Red Book — Fluoroquinolone use in children.
- British National Formulary for Children (BNFc) — Ciprofloxacin.