Ciprofloxacin (Cipro)
ciprofloxacin hydrochloride — also marketed as Cipro XR (extended-release), Cipro IV
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Complicated UTI and pyelonephritis | Adults; pediatrics (cUTI/pyelonephritis only) | Monotherapy | FDA Approved |
| Uncomplicated UTI (acute cystitis) | Adults | Monotherapy (reserve) | FDA Approved |
| Chronic bacterial prostatitis | Adults | Monotherapy | FDA Approved |
| Lower respiratory tract infections | Adults | Monotherapy or combination | FDA Approved |
| Skin and skin structure infections | Adults | Monotherapy | FDA Approved |
| Bone and joint infections | Adults | Monotherapy or combination | FDA Approved |
| Infectious diarrhea (Shigella, Campylobacter, E. coli) | Adults | Monotherapy | FDA Approved |
| Typhoid fever (S. typhi) | Adults | Monotherapy | FDA Approved |
| Inhalational anthrax (post-exposure) | All ages | First-line | FDA Approved |
| Plague (Y. pestis) | All ages | First-line | FDA Approved |
| Acute sinusitis and AECB | Adults (reserve for no alternative) | Monotherapy | FDA Approved |
Ciprofloxacin is a second-generation fluoroquinolone with potent activity against gram-negative organisms, including Pseudomonas aeruginosa, making it one of the few oral antibiotics effective against this pathogen. Its excellent tissue penetration, oral bioavailability, and broad spectrum have made it a mainstay for urinary tract infections, prostatitis, bone and joint infections, and enteric infections. However, FDA safety communications have progressively restricted its use: the 2016 boxed warning and subsequent updates advise reserving ciprofloxacin for infections without alternative treatment options when used for acute sinusitis, AECB, and uncomplicated UTI.
Spontaneous bacterial peritonitis prophylaxis: 500 mg daily in patients with cirrhosis and ascites. Widely guideline-supported. Evidence quality: High.
Neutropenic fever prophylaxis: 500 mg q12h in high-risk haematological patients. Supported by ASCO/IDSA guidelines. Evidence quality: High.
Intra-abdominal infections (with metronidazole): IDSA-recommended combination regimen. Evidence quality: High.
Malignant otitis externa: Extended course for Pseudomonas-associated skull base osteomyelitis. Evidence quality: Moderate.
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Acute uncomplicated cystitis | 250 mg q12h | 250 mg q12h | 250 mg q12h | 3 days (FDA PI); reserve for no alternative XR: 500 mg daily x 3 days |
| Complicated UTI / pyelonephritis | 500 mg q12h | 500 mg q12h | 500 mg q12h | 7–14 days (FDA PI) XR: 1000 mg daily x 7–14 days; IV: 400 mg q12h |
| Chronic bacterial prostatitis | 500 mg q12h | 500 mg q12h | 500 mg q12h | 28 days (FDA PI) |
| Lower respiratory tract infection | 500–750 mg q12h | 500–750 mg q12h | 750 mg q12h | 7–14 days; 500 mg for mild/moderate, 750 mg for severe IV: 400 mg q8–12h |
| Bone and joint infection | 500–750 mg q12h | 500–750 mg q12h | 750 mg q12h | 4–8 weeks (FDA PI) IV: 400 mg q8–12h |
| Skin & soft tissue infection | 500–750 mg q12h | 500–750 mg q12h | 750 mg q12h | 7–14 days |
| Infectious diarrhea (Shigella, Campylobacter) | 500 mg q12h | 500 mg q12h | 500 mg q12h | 5–7 days |
| Typhoid fever (S. typhi) | 500 mg q12h | 500 mg q12h | 500 mg q12h | 10 days |
| Inhalational anthrax (post-exposure) | 500 mg q12h | 500 mg q12h | 500 mg q12h | 60 days (FDA PI) IV: 400 mg q12h; switch to oral when feasible |
| Plague (Y. pestis) | 500–750 mg q12h | 500–750 mg q12h | 750 mg q12h | 14 days (FDA PI) IV: 400 mg q8–12h |
| Acute sinusitis (reserve) | 500 mg q12h | 500 mg q12h | 500 mg q12h | 10 days; use only if no alternative (FDA boxed warning) |
Pediatric Dosing (FDA-approved indications only)
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Complicated UTI / pyelonephritis (1–17 y) | 6–10 mg/kg IV q8h or 10–20 mg/kg PO q12h | Same | 400 mg IV or 750 mg PO per dose | 10–21 days; not first choice due to arthropathy risk (FDA PI) |
| Inhalational anthrax (post-exposure, all ages) | 10–15 mg/kg q12h PO/IV | 10–15 mg/kg q12h | 500 mg per dose | 60 days |
| Plague (1–17 y) | 10–15 mg/kg q8–12h | 10–15 mg/kg q8–12h | 500 mg per dose | 14 days (FDA PI) |
Renal Impairment Adjustments
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| CrCl >50 mL/min | No adjustment | Standard dose | Standard | Normal dosing interval (StatPearls) |
| CrCl 30–50 mL/min | 250–500 mg q12h | 250–500 mg q12h | 500 mg q12h | Standard dose q12h (StatPearls) |
| CrCl 5–29 mL/min | 250–500 mg q18h | 250–500 mg q18h | 500 mg q18h | Extended interval; XR: reduce to 500 mg daily (FDA PI) |
| Haemodialysis / peritoneal dialysis | 250–500 mg q24h | 250–500 mg q24h | 500 mg q24h | Administer after dialysis session (FDA PI) |
Ciprofloxacin achieves ~70% oral bioavailability with rapid absorption (Tmax 1–2 h), making early IV-to-oral switch feasible for most indications once the patient can tolerate oral intake. This is a key advantage for outpatient parenteral antibiotic therapy (OPAT) and reduces hospital length of stay. Oral 750 mg produces serum levels comparable to IV 400 mg.
Pharmacology
Mechanism of Action
Ciprofloxacin is a bactericidal antibiotic that acts by inhibiting two essential bacterial enzymes: DNA gyrase (topoisomerase II) and topoisomerase IV. DNA gyrase introduces negative supercoils into double-stranded DNA, a process critical for DNA replication, transcription, and repair. Topoisomerase IV is required for the separation (decatenation) of daughter chromosomes during cell division. By trapping these enzymes in complexes with cleaved DNA, ciprofloxacin causes double-strand DNA breaks that trigger the bacterial SOS repair response and ultimately result in cell death. This dual-target mechanism underpins ciprofloxacin’s concentration-dependent killing kinetics, where higher peak concentrations relative to the MIC (Cmax/MIC ratio) correlate with better bactericidal activity. Ciprofloxacin’s primary strength is against gram-negative aerobes, particularly Enterobacterales and Pseudomonas aeruginosa, with more modest activity against gram-positive organisms compared with respiratory fluoroquinolones like levofloxacin or moxifloxacin.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | ~70% bioavailable (oral); Tmax 1–2 h; food does not significantly impair absorption but divalent/trivalent cations (Ca, Mg, Fe, Al, Zn) and dairy products markedly reduce it | Can take with food to reduce GI upset; must separate from antacids, iron, calcium, sucralfate by ≥2 h before or 6 h after ciprofloxacin |
| Distribution | Vd 2–3 L/kg; protein binding 20–40%; excellent penetration into lung, prostate, kidney, bile, bone; crosses into CSF at ~10% of serum levels | Low protein binding enhances tissue availability; high prostate and urinary concentrations support UTI and prostatitis efficacy; good bone penetration supports osteomyelitis use |
| Metabolism | ~15–20% hepatically metabolised; 4 metabolites with limited antimicrobial activity; potent inhibitor of CYP1A2; minor inhibition of CYP3A4 | CYP1A2 inhibition drives major interactions (theophylline, tizanidine, duloxetine, caffeine); hepatic dose adjustment not established but use with caution in severe liver disease |
| Elimination | t½ 3–5 h (normal renal function); ~8 h in ESRD; renal excretion 40–60% unchanged (glomerular filtration + tubular secretion); faecal 20–35% | Predominantly renal elimination requires dose reduction in CrCl <50 mL/min; haemodialysis removes only small amounts; maintain adequate hydration to prevent crystalluria |
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| No individual AE ≥10% | — | Ciprofloxacin has a favourable tolerability profile; no single adverse effect reaches ≥10% incidence in adult clinical trials. All common AEs fall in the 1–10% range (see below). |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Nausea | 2.5–5.2% | Most common GI complaint in clinical trials. Taking with food may reduce symptoms. |
| Diarrhea | 1.6–4.8% | Monitor for C. difficile if persistent or bloody; more common in paediatric studies (4.8%) |
| Vomiting | 1–4.8% | Higher rates in paediatric trials |
| Liver function tests abnormal | 1.9% | Usually transient elevations of transaminases; discontinue if clinical hepatitis develops |
| Rash | 1–1.6% | Distinguish from serious hypersensitivity; discontinue if systemic features present |
| Headache | ~1–2% | Commonly reported in postmarketing; usually mild |
| Abdominal pain / dyspepsia | 1.7–3.3% | GI effects generally dose-related |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Tendinitis and tendon rupture [BOXED WARNING] | Uncommon; risk increased with age >60, corticosteroids, organ transplant | Hours to months; may occur after discontinuation | Discontinue immediately at first sign of tendon pain, swelling, or inflammation. Avoid exercise until tendinitis excluded. Achilles tendon most common site. |
| Peripheral neuropathy [BOXED WARNING] | Rare; may be irreversible | Days to weeks; may occur after first dose | Discontinue immediately if symptoms of neuropathy develop (pain, burning, tingling, numbness, weakness). May be irreversible. |
| CNS effects (seizures, psychosis, increased ICP, tremors) [BOXED WARNING] | Rare | Any time during therapy | Discontinue ciprofloxacin. Use with caution in patients with CNS disorders or seizure history. NSAIDs may increase seizure risk. |
| Myasthenia gravis exacerbation [BOXED WARNING] | Rare; may be fatal | Any time | Avoid in known myasthenia gravis. Discontinue immediately if muscle weakness worsens. |
| Aortic aneurysm and dissection [BOXED WARNING] | Rare; epidemiological association | During or within months of therapy | Avoid in patients with known aortic aneurysm, Marfan syndrome, Ehlers-Danlos, or elderly with hypertension unless no alternative exists. |
| QT prolongation / torsades de pointes | Rare | Any time | Avoid in patients with known QT prolongation, hypokalaemia, or concurrent QT-prolonging drugs. Monitor ECG if risk factors present. |
| Hepatotoxicity (hepatitis, hepatic failure) | Rare | Days to weeks | Discontinue if jaundice or significant LFT elevation develops; fatalities reported |
| Clostridioides difficile-associated diarrhea | Uncommon | During or up to 2 months after therapy | Stool C. difficile toxin assay; discontinue ciprofloxacin; treat with oral vancomycin or fidaxomicin |
| Hypersensitivity / anaphylaxis | Rare | After first or subsequent doses | Discontinue immediately; emergency treatment. Cross-reactivity with other fluoroquinolones possible. |
| Blood glucose disturbances (hypoglycaemia/hyperglycaemia) | Uncommon | Any time; higher risk with concurrent glucose-lowering agents | Monitor blood glucose in diabetic patients; cases of hypoglycaemic coma reported (FDA PI) |
| Photosensitivity / phototoxicity | Uncommon | During therapy | Advise sun avoidance; discontinue if severe sunburn-like reaction occurs |
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| GI intolerance (nausea, diarrhea, vomiting) | ~1–2% | Most common single reason across adult trials |
| CNS effects (dizziness, headache, insomnia) | <1% | Fluoroquinolone class effect |
| Rash / hypersensitivity | <1% | Requires evaluation for SJS/TEN if severe |
Fluoroquinolones, including ciprofloxacin, have been associated with disabling and potentially irreversible serious adverse reactions that may occur together, including tendinitis and tendon rupture, peripheral neuropathy, and CNS effects. Discontinue ciprofloxacin immediately and avoid fluoroquinolones in patients who experience any of these serious adverse reactions. Fluoroquinolones may also exacerbate muscle weakness in persons with myasthenia gravis and should be avoided in these patients. Because fluoroquinolones have been associated with serious adverse reactions, reserve ciprofloxacin for use in patients who have no alternative treatment options for acute sinusitis, AECB, and uncomplicated UTI.
Drug Interactions
Ciprofloxacin is a potent CYP1A2 inhibitor with moderate CYP3A4 inhibitory effects. This distinguishes it from most other antibiotics and creates clinically significant interactions with narrow-therapeutic-index CYP1A2 substrates. Chelation with polyvalent cations is the other major absorption-reducing interaction.
Monitoring
- Renal FunctionBaseline; periodically during prolonged therapy
RoutineCrCl or eGFR to guide dose adjustment. Maintain adequate hydration to prevent crystalluria, particularly in alkaline urine. - Hepatic FunctionIf symptoms arise
Trigger-basedMonitor LFTs if signs of hepatitis develop (jaundice, dark urine, abdominal pain). Discontinue if significant hepatotoxicity confirmed. - Tendon AssessmentOngoing throughout therapy
RoutineAsk about tendon pain, swelling, or stiffness at each visit. Counsel patients to stop ciprofloxacin and rest the affected limb immediately if symptoms arise. Risk highest in patients >60 y, on corticosteroids, or post-transplant. - Neurological StatusOngoing
RoutineAssess for CNS effects (confusion, tremor, seizures) and peripheral neuropathy (pain, burning, tingling, numbness). Discontinue if any neurological symptoms develop. - Blood GlucoseIn patients on glucose-lowering agents
Trigger-basedMonitor for hypoglycaemia or hyperglycaemia, especially in diabetic patients. Cases of hypoglycaemic coma have been reported. - INR (if on warfarin)Within 3–5 days of starting
Trigger-basedCiprofloxacin may enhance anticoagulant effect. Adjust warfarin dose as indicated. - Theophylline LevelBefore and during co-administration
Trigger-basedCYP1A2 inhibition increases theophylline levels. Fatal theophylline toxicity has been reported. Monitor levels closely and reduce theophylline dose as needed.
Contraindications & Cautions
Absolute Contraindications
- Hypersensitivity to ciprofloxacin or any fluoroquinolone
- Concurrent tizanidine — contraindicated due to severe hypotension and sedation (FDA PI)
Relative Contraindications (Specialist Input Recommended)
- Myasthenia gravis: May exacerbate muscle weakness; fatalities reported. Avoid unless no alternative (FDA boxed warning).
- Known aortic aneurysm or aortic connective tissue disorder (Marfan, Ehlers-Danlos): Epidemiological data suggest increased risk of aortic dissection.
- Known QT prolongation or concurrent QT-prolonging drugs: Risk of torsades de pointes.
- History of tendon disorders related to fluoroquinolone use: Do not re-challenge.
- Epilepsy or conditions predisposing to seizures: Fluoroquinolones lower seizure threshold; concurrent NSAIDs further increase risk.
Use with Caution
- Age >60 years: Increased risk of tendinitis, tendon rupture, and QT prolongation.
- Concurrent corticosteroid use: Additive tendon injury risk.
- Organ transplant recipients: Elevated tendinopathy risk.
- Renal impairment (CrCl <50 mL/min): Dose reduction required.
- Diabetes: Blood glucose disturbances reported; monitor closely.
- Pregnancy: Avoid if alternative available; arthropathy risk in animal models. Limited human data have not confirmed teratogenicity.
- Paediatric patients: Use only for FDA-approved indications (cUTI, anthrax, plague) due to arthropathy risk.
Fluoroquinolones, including ciprofloxacin, have been associated with disabling and potentially irreversible serious adverse reactions including tendinitis and tendon rupture, peripheral neuropathy, and central nervous system effects. These reactions can occur simultaneously in the same patient. Discontinue ciprofloxacin immediately and avoid fluoroquinolones in patients who experience any of these serious adverse reactions. Fluoroquinolones may also exacerbate muscle weakness in persons with myasthenia gravis. Avoid use in patients with a known history of myasthenia gravis. Because fluoroquinolones, including ciprofloxacin, have been associated with serious adverse reactions, reserve ciprofloxacin for use in patients with acute sinusitis, acute exacerbation of chronic bronchitis, and uncomplicated urinary tract infections who have no alternative treatment options.
Patient Counselling
Purpose of Therapy
Ciprofloxacin is a powerful antibiotic that kills bacteria by preventing them from copying their DNA. It is used for a range of serious infections, including urinary tract infections, bone infections, and certain life-threatening conditions such as anthrax and plague. Complete the full course as directed, even if you feel better early.
How to Take
Ciprofloxacin can be taken with or without food, but should be swallowed with a full glass of water. Stay well hydrated throughout treatment. Extended-release tablets (Cipro XR) should be swallowed whole and not crushed or chewed. Avoid taking ciprofloxacin at the same time as antacids, iron supplements, calcium products, or multivitamins — space these by at least 2 hours before or 6 hours after your ciprofloxacin dose. Avoid dairy products and calcium-fortified juices close to your dose.
Sources
- CIPRO (ciprofloxacin HCl) Tablets and Oral Suspension — Full Prescribing Information. Revised 9/2024. accessdata.fda.govCurrent FDA label with boxed warning, dosing for all approved indications, adverse reaction incidence data, and CYP1A2 interaction guidance.
- CIPRO XR (ciprofloxacin) Extended-Release Tablets — Full Prescribing Information. Revised 2020. accessdata.fda.govXR formulation label with once-daily dosing for UTI/pyelonephritis and renal dose adjustment guidance.
- CIPRO IV (ciprofloxacin) — Full Prescribing Information. Revised 2011. merck.comIV formulation label with dosing for severe infections and parenteral-to-oral conversion guidance.
- Patel K, Goldman JL. Safety concerns surrounding quinolone use in children. J Clin Pharmacol. 2016;56(9):1060-1075. doi:10.1002/jcph.715Review of musculoskeletal safety data in paediatric populations, supporting restricted use of fluoroquinolones in children.
- Daneman N, Lu H, Redelmeier DA. Fluoroquinolones and collagen associated severe adverse events: a longitudinal cohort study. BMJ Open. 2015;5(11):e010077. doi:10.1136/bmjopen-2015-010077Large cohort study quantifying risk of tendon rupture, retinal detachment, and aortic aneurysm associated with fluoroquinolone use.
- Gupta K, Hooton TM, Naber KG, et al. International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women: A 2010 Update by the IDSA and ESMID. Clin Infect Dis. 2011;52(5):e103-e120. doi:10.1093/cid/ciq257IDSA/ESMID UTI guideline recommending fluoroquinolones as alternatives when first-line agents cannot be used.
- Solomkin JS, Mazuski JE, Bradley JS, et al. Diagnosis and Management of Complicated Intra-abdominal Infection in Adults and Children: Guidelines by the SIS and the IDSA. Clin Infect Dis. 2010;50(2):133-164. doi:10.1086/649554IDSA guideline recommending ciprofloxacin plus metronidazole as a first-line option for community-acquired intra-abdominal infection.
- FDA Drug Safety Communication: FDA advises restricting fluoroquinolone antibiotic use for certain uncomplicated infections. July 2016 (updated 2018). fda.govKey FDA safety communication establishing restriction of fluoroquinolones for uncomplicated UTI, sinusitis, and bronchitis when alternatives exist.
- Aldred KJ, Kerns RJ, Osheroff N. Mechanism of quinolone action and resistance. Biochemistry. 2014;53(10):1565-1574. doi:10.1021/bi5000564Detailed review of DNA gyrase and topoisomerase IV inhibition, explaining concentration-dependent killing and resistance mechanisms.
- Drlica K, Zhao X. DNA gyrase, topoisomerase IV, and the 4-quinolones. Microbiol Mol Biol Rev. 1997;61(3):377-392. doi:10.1128/mmbr.61.3.377-392.1997Foundational review establishing the dual-target mechanism (DNA gyrase + topo IV) of fluoroquinolone antibacterials.
- Vance-Bryan K, Guay DR, Rotschafer JC. Clinical pharmacokinetics of ciprofloxacin. Clin Pharmacokinet. 1990;19(6):434-461. doi:10.2165/00003088-199019060-00003Comprehensive PK review establishing bioavailability (~70%), Vd (1.74–5.0 L/kg), t½ (3–4 h), protein binding, and renal/hepatic dose considerations.
- Junkert AM, Pinheiro LB, Borges KB, et al. Pharmacokinetics of oral ciprofloxacin in adult patients: a scoping review. Br J Clin Pharmacol. 2024;90(2):381-405. doi:10.1111/bcp.15933Recent scoping review consolidating PK data across 48 studies, addressing dose-adjusted AUC variability and implications for dose adjustments.
- Ciprofloxacin. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 (updated Aug 2023). ncbi.nlm.nih.govCurrent clinical pharmacology reference covering dosing adjustments in renal impairment, CRRT dosing, and paediatric PK parameters.