Ciprofloxacin
Ciprofloxacin HCl
Also known as: Cipro XR · Cipro I.V. · Ciloxan · ciprofloxacine · ciprofloxacinum · ciprofloxacino · Bay-q-3939
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5-15 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| UTI | 10 mg/kg PO once daily (q24h) | PO | q24h | 7-14 days | 🌎 NA |
| Skin, soft tissue infections | 10-15 mg/kg PO once daily (q24h) | PO | q24h | 7-14 days | 🌎 NA |
| Bone systemic infections, bacteremia and more resistant pathogens (e.g., Enterobacter) | 20 mg/kg PO once daily (q24h) | PO | q24h | 7-14 days | 🌎 NA |
| Pyoderma | 11 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Ocular infections | 1 drop to affected eye | topical | q6h | Not specified | 🌍 EU |
| Severe ocular infections (intensive therapy) | 1 drop to affected eye | topical | q30-120mins | 1-2 days | 🌍 EU |
- Susceptible infections: Avoid or reduce dosage in severe renal failure; avoid in young animals or pregnant/breeding animals.
- Ocular infections: Standard therapy
- Severe ocular infections (intensive therapy): For short-term intensive use
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5-15 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Ocular infections | 1 drop to affected eye | topical | q6h | Not specified | 🌍 EU |
| Severe ocular infections (intensive therapy) | 1 drop to affected eye | topical | q30-120mins | 1-2 days | 🌍 EU |
- Susceptible infections: Avoid or reduce dosage in severe renal failure; avoid in young animals or pregnant/breeding animals.
- Ocular infections: Standard therapy
- Severe ocular infections (intensive therapy): For short-term intensive use
Small Mammals
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections (Rabbits) | 5-20 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Susceptible infections (Chinchillas, Gerbils, Guinea Pigs, Hamsters, Mice, Rats) | 7-20 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Pasteurellosis (Rabbits) | 15-20 mg/kg PO twice daily | PO | twice daily | minimum of 14 days in mild cases and up to several months in chronic infections | 🌎 NA |
- Pasteurellosis (Rabbits): ciprofloxacin or enrofloxacin
Ferrets
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5-15 mg/kg PO twice daily | PO | twice daily | — | 🌎 NA |
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible gram-negative infections | 20-40 mg/kg PO twice daily | PO | twice daily | — | 🌎 NA |
| Susceptible gram-negative infections | 20 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Susceptible gram-negative infections | 10-15 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Susceptible infections (Ratites) | 3-6 mg/kg PO twice daily | PO | twice daily | — | 🌎 NA |
- Susceptible gram-negative infections: Using ciprofloxacin 500 mg tablets. Crushed tablet goes into suspension well, but must be shaken well before administering.
- Susceptible gram-negative infections: Using crushed tablets
- Susceptible gram-negative infections: Using crushed tablets or suspend
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Ciprofloxacin is a second-generation fluoroquinolone antibiotic widely used in human medicine and frequently utilized off-label in veterinary medicine.
- Spectrum of Activity: Broad-spectrum, highly effective against many gram-negative bacilli and cocci (including Pseudomonas aeruginosa, E. coli, Klebsiella spp.) and some gram-positive organisms (like Staphylococcus spp., including methicillin-resistant strains). It has weak activity against anaerobes and most Streptococci.
- Pharmacokinetic Pearl: In dogs, its oral bioavailability is significantly lower and more erratic than enrofloxacin (only ~40-50% compared to enrofloxacin's >80%). Therefore, it is generally not considered a direct 1:1 oral substitute for enrofloxacin in canines.
- Clinical Utility: Often selected when a true intravenous (IV) fluoroquinolone formulation is required, for specific culture-directed therapies, or when a larger oral dosage form is desired.
Mechanism of action
Ciprofloxacin is a bactericidal, concentration-dependent antibiotic.
- It enters the bacterial cell and inhibits two key type-II topoisomerase enzymes: DNA gyrase (primary target in gram-negative bacteria) and Topoisomerase IV (primary target in gram-positive bacteria).
- Inhibition of these enzymes → prevents DNA supercoiling and relaxation → halts DNA replication and transcription → rapid bacterial cell death (within 20-30 minutes of exposure).
- Exhibits a significant post-antibiotic effect (PAE), meaning bacterial growth continues to be suppressed even after drug concentrations fall below the minimum inhibitory concentration (MIC).
Safety & warnings
Contraindications
- Hypersensitivity to fluoroquinolones
- Small and medium breed dogs 2-8 months of age (due to cartilage damage)
- Large and giant breed dogs during their rapid growth phase (past 8 months of age)
- Known hypersensitivity to ciprofloxacin or other fluoroquinolones
Adverse effects
- GI distress (vomiting, anorexia)
- Cartilage abnormalities in young, growing animals
- CNS stimulation (dizziness, seizures)
- Crystalluria
- Hypersensitivity reactions
- Local irritation after application
- Local burning and itching (reported in humans)
- Lid margin crusting (reported in humans)
- Hyperaemia (reported in humans)
- Taste disturbances (reported in humans)
- Corneal staining (reported in humans)
- Keratitis (reported in humans)
- Lid oedema (reported in humans)
- Lacrimation (reported in humans)
- Photophobia (reported in humans)
- Corneal infiltrates (reported in humans)
- Nausea (reported in humans)
- Visual disturbances (reported in humans)
Precautions
Caution: Use with care in patients with severe renal or hepatic impairment (dosage adjustments may be required to prevent accumulation).
- Hydration: Animals should not be allowed to become dehydrated during therapy due to the risk of crystalluria.
- Neurologic: Use with caution in patients with seizure disorders due to potential CNS stimulation.
- Feline Retinal Toxicity: Use high doses in cats with caution. While retinal toxicity appears less likely than with enrofloxacin (as ciprofloxacin is less lipophilic), caution is still advised.
Drug interactions
May bind to ciprofloxacin and prevent its absorption; separate doses by at least 2 hours
Synergism may occur against some bacteria (particularly Pseudomonas aeruginosa)
May exacerbate nephrotoxicity and reduce the metabolism of cyclosporine
Severe hypoglycemia possible
Decreased ciprofloxacin absorption; separate doses by at least two hours
Increased MTX levels possible with resultant toxicity
May antagonize the antimicrobial activity of fluoroquinolones; concomitant use not recommended
May alter phenytoin levels
Blocks tubular secretion of ciprofloxacin and may increase its blood level and half-life
Increased risk for cardiotoxicity
May inhibit absorption of ciprofloxacin; separate doses by at least 2 hours
May increase theophylline blood levels
Potential for increased warfarin effects
Monitoring
- Clinical efficacy
- Adverse effects (GI signs, CNS stimulation)
- Hydration status
- Clinical resolution of ocular infection
- Corneal healing (via fluorescein staining)
- Signs of local irritation or hypersensitivity
Pharmacokinetics
Half-life
Absorption
Well absorbed after oral administration in most species, but in dogs, bioavailability is at least half that of enrofloxacin. Poorly absorbed in ponies (2-12%). Oral bioavailability is ~50% in calves and ~40% in pigs.
Distribution
In humans, Vd is ~23.5 L/kg and 20-40% bound to serum proteins. Protein binding is ~70% in calves and ~23% in pigs.
Metabolism
Metabolized to various metabolites that are less active than the parent compound. (Note: Ciprofloxacin is itself a major active metabolite of enrofloxacin in many species).
Elimination
Approximately 15-50% eliminated unchanged into the urine by both tubular secretion and glomerular filtration. Metabolites are eliminated in both urine and feces.
Overdose
Little specific information is available for ciprofloxacin overdosage in veterinary species. Overdoses may result in GI distress, CNS signs (tremors, seizures), or renal toxicity (crystalluria). Treatment should consist of supportive care, maintaining adequate hydration to prevent crystalluria, and gastric decontamination if ingestion was recent. See the enrofloxacin monograph for more extrapolated information.
Available products
Formulations
- Extended-release oral tablets
- Microcapsules for oral suspension
- Solution for injection
- Ophthalmic: 0.3% solution in 5 ml bottle
Veterinary
- None
Human-labeled
- Ciprofloxacin Oral Tablets: 100 mg, 250 mg, 500 mg & 750 mg; Cipro®; generic
- Ciprofloxacin Extended-Release Oral Tablets: 500 mg & 1000 mg; Cipro XR®; generic
- Ciprofloxacin Microcapsules for Oral Suspension: 250 mg/5 mL (5%) & 500 mg/5 mL (10%) when reconstituted; Cipro®
- Ciprofloxacin Solution for Injection: 200 mg & 400 mg in 100 mL & 200 mL in 5% dextrose flexible containers (0.2%); Cipro® I.V.; generic
- Ciloxan 0.3% w/v eye drops, solution
Regulatory status
Subject to veterinary prescription. Fluoroquinolones are restricted for use only when other antibiotics are ineffective.
POM-V or POM (human crossover). Must adhere to responsible antimicrobial use guidelines.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets should be stored in tight containers at temperatures less than 30°C. Protect from strong UV light. The injection should be stored at 5°-25°C and protected from light and freezing.
Client information
Important: Give this medication exactly as prescribed, and do not skip doses to ensure the infection is fully treated.
- Administration: Best given on an empty stomach. If it causes stomach upset, a small treat is okay, but do not give with dairy products (cheese, milk, yogurt) as the calcium prevents the drug from being absorbed.
- Supplements: Separate from antacids, iron, or zinc supplements by at least 2 hours.
- Hydration: Ensure your pet has access to plenty of fresh water at all times to prevent crystal formation in the urine.
- Side Effects: Watch for vomiting, loss of appetite, or unusual neurologic signs (like dizziness or tremors). Contact your veterinarian if these occur.
- Growing Pets: This drug is generally avoided in young, growing animals as it can cause joint and cartilage problems.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.