Nitrofurantoin  (PDF Version)


Antibiotic Class:



Antimicrobial Spectrum:

E. coli, Citrobacter spp., S. sapprophyticus, E. faecalis.


Mechanism of Action:

Inhibits bacterial enzymes responsible for cell wall synthesis



No data



Bioavailability: 90%, Tmax: 2 hours, Cmax (50mg PO): 0.4mcg/ml, Volume of distribution: 40L, Half-life: 1 hour


Adverse Effects:

CNS: Headache, dizziness, confusion

GI: nausea, vomiting, pancreatitis

Hematologic: Eosinophilia and fever

Other: Peripheral neuritis



Capsule, macrocrystal: 25, 50, 100 mg

Capsule, macrocrystal/monohydrate: 100 mg

Suspension, oral: 25 mg/5 mL


Adults   UTI, treatment: Oral: 50-100 mg/dose every 6 hours (not to exceed 400 mg/24 hours)

               UTI, prophylaxis:: Oral: 50-100 mg/dose at bedtime

Children: UTI, treatment: Oral: Children >1 month: 5-7 mg/kg/day in divided doses every 6               hours; maximum: 400 mg/day

               UTI, chronic therapy: Oral: 1-2 mg/kg/day in divided doses every 12-24 hours; maximum: 100 mg/day


Disease state based dosing:

Renal failure:  Contraindicated in patients with CrCl < 60ml/min, hemodialysis, peritoneal dialysis, and hemofiltration

Hepatic failure:  No data





Drug Interactions:

Phenytoin Increased metabolism of phenytoin suggested

Magnessium trisilicate antacids Decreased nitrofurantoin absorption

Probenecid Decreased tubular secretion of nitrofurantoin

Quinolones In-vitro antagonism clinical significance unknown



Category B: No evidence of risk in humans but studies inadequate.


Monitoring requirements:

Therapeutic: Culture and sensitivities, signs and symptoms of infection

Toxic:  Signs/Symptoms of polyneuropathy


Brand names/Manufacturer: