Ciprofloxacin Dosing for Bacterial Infections
For most bacterial infections, ciprofloxacin is dosed at 500 mg orally twice daily, with duration and dose adjustments based on infection severity and site: 250 mg twice daily for uncomplicated UTIs (3-7 days), 500 mg twice daily for moderate infections (7-14 days), and 750 mg twice daily for severe/complicated infections (7-14 days to 6 weeks depending on site). 1
Standard Dosing by Infection Type
Urinary Tract Infections
- Uncomplicated cystitis: 250 mg orally twice daily for 3 days (minimum effective dose) 2, though fluoroquinolones should be reserved as alternatives when other agents cannot be used 3
- Complicated UTI/Pyelonephritis: 500 mg orally twice daily for 7 days 3, 1
- Extended-release formulation: 1000 mg once daily for 7 days is equally effective as 500 mg twice daily 3, 4
- Initial IV therapy option: 400 mg IV may be given before switching to oral therapy, particularly if local fluoroquinolone resistance exceeds 10% 3
Respiratory Tract Infections
- Mild to moderate: 500 mg orally twice daily for 7-14 days 1
- Severe/complicated: 750 mg orally twice daily for 7-14 days 1
- Community-acquired pneumonia: 750 mg orally twice daily for 3-6 days, then 500 mg twice daily for 4-7 days has shown 100% success rates 5
Skin and Soft Tissue Infections
- Mild to moderate: 500 mg orally twice daily for 7-14 days 1
- Severe/complicated: 750 mg orally twice daily for 7-14 days 1
- Bite wounds (animal/human): 500-750 mg orally twice daily 6
Bone and Joint Infections
- All severities: 500 mg (mild/moderate) to 750 mg (severe) orally twice daily for ≥4-6 weeks 1
Gastrointestinal Infections
- Infectious diarrhea: 500 mg orally twice daily for 5-7 days 1
- Traveler's diarrhea (empiric): 500 mg orally twice daily for 3-7 days 6
- Salmonella gastroenteritis in HIV patients: 750 mg orally twice daily for 14 days 6
- Typhoid fever: 500 mg orally twice daily for 10 days 1
Inhalational Anthrax (Post-Exposure)
- Adults: 500 mg orally twice daily for 60 days 6, 1
- Children: 15 mg/kg (maximum 500 mg per dose) orally twice daily for 60 days 6, 1
Other Infections
- Chronic bacterial prostatitis: 500 mg orally twice daily for 28 days 1
- Acute sinusitis: 500 mg orally twice daily for 10 days 1
- Intra-abdominal (complicated): 500 mg orally twice daily for 7-14 days 1
- Uncomplicated gonorrhea: 250 mg single dose (though resistance now limits this use) 1
Pediatric Dosing
Fluoroquinolones should be used with extreme caution in children and only when no alternatives exist due to concerns about joint/cartilage toxicity. 6
- Complicated UTI/Pyelonephritis:
- Inhalational anthrax: 15 mg/kg (maximum 500 mg) orally every 12 hours for 60 days 6, 1
- Maximum daily dose: Should not exceed 1 gram per day in children 6
- Consultation recommended: Pediatric infectious diseases specialist consultation is suggested before using ciprofloxacin in children 6
Special Populations
Renal Impairment
Dosing adjustments are required based on creatinine clearance 1:
- CrCl >50 mL/min: Standard dosing
- CrCl 30-50 mL/min: 250-500 mg every 12 hours
- CrCl 5-29 mL/min: 250-500 mg every 18 hours
- Hemodialysis/peritoneal dialysis: 250-500 mg every 24 hours (after dialysis)
- Severe infections with severe renal impairment: 750 mg may be used at the above intervals with careful monitoring 1
Pregnancy
Fluoroquinolones should be avoided during pregnancy. 6 However, for life-threatening infections (e.g., inhalational anthrax), ciprofloxacin may be used as the risk of infection outweighs drug risks 6. Adverse effects on developing teeth and bones are dose-related, so short-term use (7-14 days) before six months of gestation may be considered for serious infections 6.
HIV-Infected Patients
- Traveler's diarrhea prophylaxis: 500 mg orally once daily when prophylaxis is deemed necessary 6
- Salmonella gastroenteritis treatment: 750 mg orally twice daily for 14 days to prevent extraintestinal spread 6
IV to Oral Conversion
Patients may be switched from IV to oral therapy when clinically appropriate 1:
- 200 mg IV every 12 hours = 250 mg oral every 12 hours
- 400 mg IV every 12 hours = 500 mg oral every 12 hours
- 400 mg IV every 8 hours = 750 mg oral every 12 hours
Sequential IV/oral therapy is as effective as continuous IV therapy and allows earlier hospital discharge 7.
Critical Clinical Considerations
Resistance Patterns
- Obtain cultures before initiating therapy for pyelonephritis and serious infections 3
- If local fluoroquinolone resistance exceeds 10%, administer an initial long-acting parenteral antimicrobial before starting oral ciprofloxacin 3
- Reserve fluoroquinolones for situations where other antimicrobials cannot be used for uncomplicated cystitis due to resistance concerns 3
Drug Interactions
- Separate from multivalent cations: Take ciprofloxacin at least 1-2 hours before, or 4 hours after, antacids, calcium, or aluminum-containing preparations 6
- Monitor anticoagulation: Enhanced effects of warfarin and other vitamin K antagonists 6
- QT prolongation risk: Baseline ECG, repeat at 2 weeks and after adding any QT-prolonging medications 6
Common Pitfalls
- Pneumonia failures: Most treatment failures occur with pneumonia (2 of 5 ciprofloxacin failures in one study) 7
- Meningitis: Doxycycline may be preferred over ciprofloxacin for CNS infections due to better penetration 6
- Enterococcal coverage: Ciprofloxacin lacks reliable enterococcal activity; consider alternative agents for suspected enterococcal infections 7
- Fungal superinfections: Occur in 26% of patients, most commonly genitourinary with indwelling catheters 7