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

Pediatric Dosing


  • >12yrs: 400mg PO BID x 14d

Typhoid fever

  • 20mg/kg BID x 10d, max 400mg/dose

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 [1]
  • 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[2]

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. 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.
  2. Sanford Guide to Antimicrobial Therapy 2014