• Type: Fluroquinolones
  • Dosage Forms: 200,300,400, topical/otic
  • Common Trade Names: Floxin, Floxin Otic

Adult Dosing

Infections, bacterial

  • 200-400mg PO q12h

Infections, chlamydial

  • 300mg PO q12h x 7d

Urethritis, nongonococcal

  • 300mg PO q12h x 7d


  • 300mg PO q12h x 10d

Typhoid fever

  • 400mg PO q12h x 7-14d

Otitis Externa

  • 5 drops in affected ear BID x 7 days[1]
    • Safe with perforations

Pediatric Dosing


  • >12yrs: 400mg PO BID x 14d

Typhoid fever

  • 20mg/kg BID x 10d, max 400mg/dose

Otitis Externa

  • 6mo-13 yo: 5 drops in affected ear BQD x 7 days
  • >13 yo: 5 drops in affected ear BID x 7 days[1]

Special Populations

  • Pregnancy: C (risk cannot be excluded)
  • Lactation: probably safe
  • Renal Dosing
    • Adult
      • GFR 20-50: give q24h
      • GFR < 20: give usual dose x1, then decrease dose 50% q24h
      • HD: give 100-200mg after dialysis
    • Pediatric
      • specific adjustment not defined though adjustment may be required
  • Hepatic Dosing
    • Adult
      • cirrhosis: max 400mg/24h
    • Pediatric
      • specific adjustment not defined though adjustment may be required


  • Allergy to class/drug
  • myasthenia gravis
  • prolonged QT
  • history of torsades de pointes
  • caution if ventricular arrhythmias, bradycardia, recent MI
  • caution if CHF, patient > 60
  • caution if history of renal, heart, lung transplant
  • caution in seizure disorder
  • caution in DM

Adverse Reactions


  • Anaphylaxis
  • Seizure
  • Phototoxicity
  • Superinfection
  • Increased ICP
  • Toxic psychosis
  • Vasculitis
  • Serum sickness
  • Hypersensitivity pneumonitis
  • QT prolongation
  • Torsades de pointes
  • Peripheral neuropathy
  • Hepatotoxicity
  • Nephrotoxicity
  • Crystalluria
  • Myelosuppression
  • Blood dyscrasias
  • Tendonitis or tendon rupture (black box warning) - increased risk in age >60, immunosuppressed, corticosteroid use
  • Myasthenia exacerbation
  • Severe Hypoglycemia [2]
  • mental health effects



  • Half-life: 4-8h, if GFR < 10 then 17-28h
  • Metabolism: liver minimally
  • Excretion: urine primarily (70-90% unchanged), bile/feces (4-8%)
  • Mechanism of Action: inhibits DNA gyrase and topoisomerase IV

Antibiotic Sensitivities[3]

Group Organism Sensitivity
Gram Positive Strep. Group A, B, C, G I
Strep. Pneumoniae I
Viridans strep R
Strep. anginosus gp R
Enterococcus faecalis U
Enterococcus faecium R
Staph. Epidermidis S
C. jeikeium R
L. monocytogenes R
Gram Negatives N. gonorrhoeae I
N. meningitidis S
Moraxella catarrhalis S
H. influenzae S
E. coli S
Klebsiella sp S
E. coli/Klebsiella ESBL+ S
E coli/Klebsiella KPC+ R
Enterobacter sp, AmpC neg S
Enterobacter sp, AmpC pos S
Serratia sp S
Serratia marcescens X1
Salmonella sp S
Shigella sp S
Proteus mirabilis S
Proteus vulgaris S
Providencia sp. S
Morganella sp. S
Citrobacter freundii S
Citrobacter diversus S
Citrobacter sp. S
Aeromonas sp S
Acinetobacter sp. I
Pseudomonas aeruginosa I
Burkholderia cepacia R
Stenotrophomonas maltophilia R
Yersinia enterocolitica S
Francisella tularensis X1
Brucella sp. X1
Legionella sp. S
Pasteurella multocida S
Haemophilus ducreyi X1
Vibrio vulnificus X1
Misc Chlamydophila sp S
Mycoplasm pneumoniae S
Rickettsia sp X1
Mycobacterium avium X1
Anaerobes Actinomyces I
Bacteroides fragilis R
Prevotella melaninogenica I
Clostridium difficile X1
Clostridium (not difficile) I
Fusobacterium necrophorum X1
Peptostreptococcus sp. I


  • S susceptible/sensitive (usually)
  • I intermediate (variably susceptible/resistant)
  • R resistant (or not effective clinically)
  • S+ synergistic with cell wall antibiotics
  • U sensitive for UTI only (non systemic infection)
  • X1 no data
  • X2 active in vitro, but not used clinically
  • X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
  • X4 active in vitro, but not clinically effective for strep pneumonia

See Also


  1. 1.0 1.1 Clinical Practice Guideline: Acute Otitis Externa Executive Summary. Otolaryngology -- Head and Neck Surgery 2014 150: 161 DOI: 10.1177/0194599813517659 PDF
  2. FDA updates warnings for fluoroquinolone antibiotics on risks of mental health and low blood sugar adverse reactions. US Food and Drug Administration. https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm612995.htm. Updated July 10, 2018. Accessed Oct 22, 2018.
  3. Sanford Guide to Antimicrobial Therapy 2014