Ciprofloxacin
Brand names: Ciproxin
Ciprofloxacin is a fluoroquinolone antibiotic with broad Gram-negative activity, used for urinary, respiratory, gastrointestinal and certain other infections including those caused by Pseudomonas.
Adult dose
Paediatric dose
Dose adjustments
CrCl 30-60 mL/min/1.73m2: 250-500 mg every 12 h. CrCl <30 mL/min/1.73m2: 250-500 mg every 24 h. Haemodialysis: 250-500 mg every 24 h (after dialysis). Peritoneal dialysis: 250-500 mg every 24 h. No dose adjustment needed in hepatic impairment.
Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.
Cystic fibrosis: 20 mg/kg twice daily (max 750 mg/dose) for 10-14 days. Complicated UTI and pyelonephritis: 10 to 20 mg/kg twice daily (max 750 mg/dose) for 10-21 days. Inhalation anthrax post-exposure prophylaxis/treatment: 10 to 15 mg/kg twice daily (max 500 mg/dose) for 60 days. Other severe infections: 20 mg/kg twice daily (max 750 mg/dose). Dosing in children with renal/hepatic impairment has not been studied. Verify paediatric dosing against a current children's formulary.
Contraindications
- Hypersensitivity to ciprofloxacin, other quinolones, or any excipient
- Concomitant administration with tizanidine
Side effects
- Nausea (most common)
- Diarrhoea (most common)
- Vomiting
- Gastrointestinal and abdominal pain
- Headache, dizziness
Interactions
- Tizanidine (contraindicated)
- Dairy products and mineral-fortified juice reduce absorption (avoid taking together)
Clinical monograph
How it works
It inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, preventing DNA replication and leading to bacterial cell death.
Prescribing in practice
- MHRA warns of disabling and potentially irreversible tendon, musculoskeletal and neuropsychiatric reactions; stop at the first sign of tendon pain or inflammation and avoid in patients at high risk.
- It prolongs the QT interval and can cause aortic aneurysm/dissection, so use caution with other QT-prolonging drugs and in those with aneurysm risk factors.
- Ciprofloxacin inhibits CYP1A2 and markedly raises theophylline and tizanidine levels; it also potentiates warfarin and chelates with calcium, antacids and iron.
Monitoring
Monitor for tendon, neurological and psychiatric symptoms throughout treatment, and review interacting drugs such as theophylline and warfarin.
Counselling the patient
- Stop and seek advice immediately if you develop tendon pain or swelling.
- Avoid taking it at the same time as dairy products, antacids or iron, which block absorption.
- Report new numbness, tingling, mood changes or palpitations.
Evidence & guidelines
The MHRA has issued repeated safety warnings (2019 and 2023) restricting fluoroquinolone use because of the risk of long-lasting and disabling adverse effects.
Reference: MHRA Quinolone Safety Update 2018/2019; NICE NG112 (UTI in Adults); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.
- Centor / McIsaac Score for Strep Pharyngitis · Throat
- CISNE Score for Febrile Neutropenia · Febrile Neutropenia
- FeverPAIN Score for Strep Throat · Throat
- Jarisch-Herxheimer Reaction Severity Assessment · Treatment Reactions
- PID Severity (CDC Diagnostic Criteria) · Gynaecological Infections
- Gustilo-Anderson Classification (Open Fractures) · Fracture Classification
- Sepsis Screening and Sepsis Six · UK Sepsis Trust; NICE NG51; Surviving Sepsis Campaign 2021
- Unintentional Weight Loss Workup · NICE NG12; BSG
- Chronic Fatigue Workup · NICE NG206; BMJ Best Practice
- Lymphadenopathy Workup · NICE NG12; BMJ Best Practice
- Pre-op Medical Clearance · NICE NG45; ESC 2022
- Secondary Hypertension Workup · NICE NG136; ESH 2023