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Pronunciation: nor-FLOX-a-sin
Class: Fluoroquinolone

Trade Names

- Tablets 400 mg

Apo-Norflox (Canada)
CO Norfloxacin (Canada)


Interferes with microbial DNA synthesis.

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Norfloxacin is rapidly absorbed; 30% to 40% absorbed in fasting patients. Food and dairy products decrease absorption. Steady state is 2 days, C max is 0.8 to 2.4 mcg/mL, and T max is approximately 1 h after dosing.


Protein binding is 10% to 15% and crosses the placenta.


Suggested as first-pass metabolism; however, further study is needed.


Norfloxacin is eliminated in urine (26% to 32% as norfloxacin, 5% to 8% as active metabolites) and feces (30%).

Special Populations

Renal Function Impairment

Renal insufficiency increases half-life. Alteration of dose is necessary.


No dosage adjustment is required based on age alone.

Indications and Usage

Treatment of UTIs caused by susceptible organisms; treatment of STDs caused by Neisseria gonorrhoeae ; prostatitis caused by  Escherichia coli .


Hypersensitivity or tendonitis associated with the use of norfloxacin or any member of the quinolone class of antimicrobial agents; hypersensitivity to any component of the product.

Dosage and Administration


PO Uncomplicated UTIs due to E. coli , Klebsiella pneumoniae , or Proteus mirabilis : 400 mg every 12 h for 3 days. Uncomplicated UTIs caused by other indicated organisms: 400 mg every 12 h for 7 to 10 days. Complicated UTIs: 400 mg every 12 h for 10 to 21 days.


PO 800 mg as single dose.

Prostatitis Caused By E. coli

PO 400 mg every 12 h for 28 days.

Renal function impairment

PO Patients who have a CrCl of 30 mL/min per 1.73 m 2 or less should receive 400 mg once daily.

General Advice

  • Tablets
  • Give 1 h before or 2 h after meals with full glass of water.
  • Do not administer antacids within 2 h of dose.


Store at controlled room temperature (59° to 86°F).

Drug Interactions

Antacids, didanosine, iron salts, multivitamins, sucralfate, zinc salts

May decrease oral absorption of norfloxacin.


Anticoagulant effect of warfarin may be increased.

Antineoplastic agents

Serum norfloxacin levels may be decreased.


Caffeine plasma concentrations may be elevated and the half-life may be prolonged.


Elevated serum cyclosporine levels.

CYP1A2 substrates (eg, caffeine, clozapine, ropinirole, tacrine, theophylline, tizanidine)

Plasma concentrations of these agents may be elevated, increasing the pharmacologic effects and adverse reactions.


The antimicrobial effect of norfloxacin may be reduced; coadministration is not recommended.


Risk of CNS convulsions and convulsive seizures may be increased.


Norfloxacin urinary elimination may be reduced.

Sulfonylureas (eg, glyburide)

Severe hypoglycemia has been reported. Monitor blood glucose during coadministration of these agents.


Decreased Cl and increased plasma levels of theophylline may result in toxicity.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Prolonged QTc interval and ventricular arrhythmia, including torsades de pointes (postmarketing).


Dizziness, headache (3%); asthenia (1%); ataxia; generalized seizures; Guillain-Barré syndrome; hypoesthesia; myoclonus; paresthesia; peripheral neuropathy; psychic disturbances, including psychotic reactions and confusion; tremors (postmarketing).


Erythema multiforme, exfoliative dermatitis, photosensitivity/phototoxicity, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria (postmarketing).


Diplopia, hearing loss, tinnitus (postmarketing).


Nausea (4%); dysgeusia, pancreatitis, pseudomembranous colitis, stomatitis (postmarketing).


Interstitial nephritis, renal failure (postmarketing).


Hepatic failure, including death; hepatitis; jaundice, including cholestatic jaundice and elevated LFTs (postmarketing).


Agranulocytosis, hemolytic anemia sometimes associated with G6PD deficiency, leukopenia, neutropenia, thrombocytopenia (postmarketing).


Angioedema; hypersensitivity, including anaphylactoid reactions; vasculitis (postmarketing).

Lab Tests

Eosinophilia, increased AST (2%); decreased neutrophil count, decreased platelets, decreased WBC, increased alkaline phosphatase, increased ALT, increased urine protein (1%).


Arthralgia, arthritis, elevated creatine kinase, exacerbation of myasthenia gravis, myalgia, tendonitis, tendon rupture (postmarketing).


Dyspnea (postmarketing).


Abdominal cramping (2%).




Norfloxacin has been associated with an increased risk of tendonitis and tendon rupture in patients of all ages. The risk is increased in patients older than 60 yr of age, in patients taking corticosteroids, and in patients with kidney, heart, or lung transplants.


Category C .




Safety and efficacy not established (oral form).

Renal Function

Reduced Cl may occur in patients with renal function impairment; adjust dose accordingly.


Use of antibiotics may result in bacterial or fungal overgrowth.


Moderate to severe reactions have occurred; avoid excessive sunlight and UV light.


CNS stimulation can occur; use drug with caution in patients with known or suspected CNS disorders.

Convulsions and toxic psychosis

Convulsions, increased intracranial pressure, and toxic psychosis have been reported with quinolone antibiotics. Quinolones may also cause CNS stimulation that may lead to tremors, restlessness, light-headedness, confusion, and hallucinations. Use with caution in patients with a history of seizures or other CNS disorders.


Has been reported when the recommended dose has been exceeded. As a precaution, the daily dose should not be exceeded; patients should drink sufficient fluids to ensure a proper state of hydration and adequate urinary output.


Serious and occasionally fatal hypersensitivity (anaphylactic) reactions has been reported.

Myasthenia gravis

May be exacerbated by norfloxacin, leading to life-threatening weakness of the respiratory muscles.

Peripheral nephropathy

Sensory or sensorimotor axonal polyneuropathy resulting in paresthesias, hypesthesia, dysesthesias, and weakness has been reported in patients taking quinolones.

Pseudomembranous colitis

Consider possibility in patients who develop diarrhea.

Serious reactions

Clinical manifestations of serious and sometimes fatal reactions that have been reported with norfloxacin include acute hepatic necrosis or failure, acute renal insufficiency or failure, agranulocytosis, allergic pneumonitis, anemia (including hemolytic and aplastic), arthralgia, fever, hepatitis, interstitial nephritis, jaundice, leukopenia, myalgia, pancytopenia, rash, serum sickness, Stevens-Johnson syndrome, thrombocytopenia (including thrombotic thrombocytopenic purpura), toxic epidermal necrolysis, vasculitis.



Crystalluria, possible QT prolongation.

Patient Information

  • Advise patient to take medication on empty stomach with full glass of water.
  • Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.
  • Advise patient not to double the dose if 1 dose is missed and to notify health care provider if more than 1 dose is missed.
  • Advise patient to notify health care provider of any diarrhea, dizziness, lethargy, nausea, rashes, shortness of breath, or unusual headache.
  • Instruct patient to maintain increased fluid intake (if not contraindicated) while taking this medication.
  • Advise patient to use caution when driving or performing tasks that require mental alertness until effects of medication are determined.
  • Remind patient to complete full course of therapy, even if symptoms of urinary tract or eye infection have resolved.
  • Instruct patient to stop treatment and inform health care provider if experiencing pain, inflammation, or rupture of tendon, and to rest or refrain from exercise until diagnosis of tendonitis or tendon rupture is excluded.

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