Fluoroquinolone Antibiotic Pregnancy: Avoid — theoretical risk of fetal arthropathy (cartilage damage seen in animal studies). Use alternatives (cephalosporins, penicillins) in pregnancy.

Ciprofloxacin

Brand names: Ciproxin

Adult dose

Dose: UTI (complicated): 500mg BD for 7–14 days. Prostatitis: 500mg BD for 28 days. Community-acquired pneumonia (Gram-negative cover): 500–750mg BD for 7–14 days. Salmonella/Shigella (travellers' diarrhoea): 500mg BD for 3–5 days. Intra-abdominal infections (with metronidazole): 400mg IV BD.

Route: Oral / IV

Frequency: Twice daily

Max: 750mg BD (oral); 400mg TDS (IV — severe infections)

MHRA 2018 and 2019 safety restrictions: quinolone-class drugs are associated with disabling and potentially permanent side effects — tendinopathy, tendon rupture, peripheral neuropathy, central nervous system effects, and aortic aneurysm. Reserve for situations where other antibiotics are inappropriate. Avoid in patients aged >60 years with concurrent corticosteroids (tendon rupture risk).

Paediatric dose

Dose: 10 mg/kg

Route: Oral / IV

Frequency: Twice daily

Max: 400mg BD (oral); 400mg TDS (IV)

BNFc: Licensed for complicated UTI, pseudomonal lung infections in cystic fibrosis, and anthrax prophylaxis/treatment in children. 1 month–17 years: 10mg/kg BD (max 400mg BD oral). Generally avoid in children unless no suitable alternative — risk of arthropathy. Seek specialist paediatric opinion.

Dose adjustments

Renal

eGFR 15–29: 250–500mg BD. eGFR <15 / dialysis: 250–500mg OD.

Hepatic

Severe hepatic impairment: reduce dose — hepatic metabolism.

Paediatric weight-based calculator

Patient weight (kg)

Clinical pearls

MHRA 2019: quinolones should only be prescribed for serious infections where other antibiotics are inappropriate — their risk profile (tendinopathy, neuropathy, aortic events) outweighs benefit for minor infections like simple UTI, acute LRTI, or acute exacerbation of COPD
Tendon rupture: stop ciprofloxacin immediately if patient develops pain, swelling, or inflammation in any tendon — most commonly Achilles. Rest, immobilise, and do not rechallenge
Food/drug separation: antacids, iron, and dairy products dramatically reduce absorption — take ciprofloxacin 2h before or 6h after these
Theophylline: always check theophylline level before starting ciprofloxacin in patients on theophylline — toxicity (arrhythmia, seizures) can occur within 24h of starting ciprofloxacin

Contraindications

Previous tendinopathy with quinolone
Concurrent corticosteroid use + age >60 (tendon rupture risk — MHRA)
QT prolongation
Epilepsy (lowers seizure threshold)
Hypersensitivity to quinolones

Side effects

Tendinopathy and tendon rupture (Achilles most common — stop immediately if tendon pain)
Peripheral neuropathy (potentially irreversible)
CNS effects (dizziness, headache, insomnia, rarely seizures, psychosis)
QTc prolongation
GI upset, nausea
C. difficile-associated diarrhoea
Photosensitivity
Aortic aneurysm (rare — MHRA warning)
Dysglycaemia (particularly if on antidiabetic drugs)

Interactions

Antacids, iron, calcium, dairy products — reduce ciprofloxacin absorption by up to 90%; separate by 2h
Warfarin — potentiates anticoagulant effect; monitor INR
Theophylline — ciprofloxacin inhibits CYP1A2; theophylline levels rise (toxicity risk); reduce theophylline dose
NSAIDs — additive seizure risk
QT-prolonging drugs — additive

Monitoring

Response to treatment (48–72h)
Tendon symptoms (ask at every review)
Blood glucose (dysglycaemia monitoring)
Theophylline levels (if co-prescribed)
ECG (QTc if risk factors)

Reference: BNFc; BNF 90; MHRA Quinolone Safety Update 2018/2019; NICE NG112 (UTI in Adults). Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

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