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Nitrofurantoin Dosage

Medically reviewed by Drugs.com. Last updated on Feb 24, 2020.

Applies to the following strengths: macrocrystals 50 mg; macrocrystals 100 mg; macrocrystals 25 mg; macrocrystals-monohydrate 100 mg; 25 mg/5 mL; macrocrystals

Usual Adult Dose for Cystitis

Capsules (macrocrystals) and oral suspension: 50 to 100 mg orally 4 times a day
Dual-release capsules (macrocrystals-monohydrate): 100 mg orally every 12 hours

Duration of Therapy:
-Capsules (macrocrystals) and oral suspension: 1 week or at least 3 days after sterility of urine obtained
-Dual-release capsules (macrocrystals-monohydrate): 7 days

Comments:
-Capsules (macrocrystals) and oral suspension: The lower dose is recommended for uncomplicated urinary tract infections (UTIs).
-Capsules (macrocrystals) and oral suspension: Reevaluation is needed with continued infection.

Uses:
-Capsules (macrocrystals) and oral suspension: For the treatment of UTIs when due to susceptible strains of Escherichia coli, enterococci, Staphylococcus aureus, and certain susceptible strains of Klebsiella and Enterobacter species
-Dual-release capsules (macrocrystals-monohydrate): For the treatment of acute uncomplicated UTIs (acute cystitis) due to susceptible strains of E coli or S saprophyticus

Usual Adult Dose for Urinary Tract Infection

Capsules (macrocrystals) and oral suspension: 50 to 100 mg orally 4 times a day
Dual-release capsules (macrocrystals-monohydrate): 100 mg orally every 12 hours

Duration of Therapy:
-Capsules (macrocrystals) and oral suspension: 1 week or at least 3 days after sterility of urine obtained
-Dual-release capsules (macrocrystals-monohydrate): 7 days

Comments:
-Capsules (macrocrystals) and oral suspension: The lower dose is recommended for uncomplicated urinary tract infections (UTIs).
-Capsules (macrocrystals) and oral suspension: Reevaluation is needed with continued infection.

Uses:
-Capsules (macrocrystals) and oral suspension: For the treatment of UTIs when due to susceptible strains of Escherichia coli, enterococci, Staphylococcus aureus, and certain susceptible strains of Klebsiella and Enterobacter species
-Dual-release capsules (macrocrystals-monohydrate): For the treatment of acute uncomplicated UTIs (acute cystitis) due to susceptible strains of E coli or S saprophyticus

Usual Adult Dose for Cystitis Prophylaxis

Capsules (macrocrystals) and oral suspension: Reducing dose to 50 to 100 mg orally once a day at bedtime may be adequate.

Comments:
-The benefits of therapy should be weighed against the potential risks (e.g., chronic pulmonary reactions).

Use: For long-term suppressive therapy

Usual Pediatric Dose for Cystitis

Capsules (Macrocrystals) and Oral Suspension:
1 month or older: 5 to 7 mg/kg/day orally in 4 divided doses
-Maximum dose: 400 mg/day

Fixed dosing recommendations (oral suspension):
-Weight 7 to 11 kg: 12.5 mg orally 4 times a day
-Weight 12 to 21 kg: 25 mg orally 4 times a day
-Weight 22 to 30 kg: 37.5 mg orally 4 times a day
-Weight 31 to 41 kg: 50 mg orally 4 times a day
-Weight at least 42 kg: 50 to 100 mg orally 4 times a day

Dual-Release Capsules (Macrocrystals-Monohydrate):
12 years or older: 100 mg orally every 12 hours

Duration of Therapy:
-Capsules (macrocrystals) and oral suspension: 1 week or at least 3 days after sterility of urine obtained
-Dual-release capsules (macrocrystals-monohydrate): 7 days

Comments:
-Capsules (macrocrystals) and oral suspension: Reevaluation is needed with continued infection.
-Capsules (macrocrystals) and oral suspension: The fixed dosing recommendations are based on an average weight in each range receiving 5 to 6 mg/kg/day in 4 divided doses; the adult dose is recommended for pediatric patients weighing at least 42 kg.

Uses:
-Capsules (macrocrystals) and oral suspension: For the treatment of UTIs when due to susceptible strains of E coli, enterococci, S aureus, and certain susceptible strains of Klebsiella and Enterobacter species
-Dual-release capsules (macrocrystals-monohydrate): For the treatment of acute uncomplicated UTIs (acute cystitis) due to susceptible strains of E coli or S saprophyticus

Usual Pediatric Dose for Urinary Tract Infection

Capsules (Macrocrystals) and Oral Suspension:
1 month or older: 5 to 7 mg/kg/day orally in 4 divided doses
-Maximum dose: 400 mg/day

Fixed dosing recommendations (oral suspension):
-Weight 7 to 11 kg: 12.5 mg orally 4 times a day
-Weight 12 to 21 kg: 25 mg orally 4 times a day
-Weight 22 to 30 kg: 37.5 mg orally 4 times a day
-Weight 31 to 41 kg: 50 mg orally 4 times a day
-Weight at least 42 kg: 50 to 100 mg orally 4 times a day

Dual-Release Capsules (Macrocrystals-Monohydrate):
12 years or older: 100 mg orally every 12 hours

Duration of Therapy:
-Capsules (macrocrystals) and oral suspension: 1 week or at least 3 days after sterility of urine obtained
-Dual-release capsules (macrocrystals-monohydrate): 7 days

Comments:
-Capsules (macrocrystals) and oral suspension: Reevaluation is needed with continued infection.
-Capsules (macrocrystals) and oral suspension: The fixed dosing recommendations are based on an average weight in each range receiving 5 to 6 mg/kg/day in 4 divided doses; the adult dose is recommended for pediatric patients weighing at least 42 kg.

Uses:
-Capsules (macrocrystals) and oral suspension: For the treatment of UTIs when due to susceptible strains of E coli, enterococci, S aureus, and certain susceptible strains of Klebsiella and Enterobacter species
-Dual-release capsules (macrocrystals-monohydrate): For the treatment of acute uncomplicated UTIs (acute cystitis) due to susceptible strains of E coli or S saprophyticus

Usual Pediatric Dose for Cystitis Prophylaxis

Capsules (Macrocrystals) and Oral Suspension:
1 month or older: Doses as low as 1 mg/kg/day orally in 1 or 2 divided doses may be adequate.
-Maximum dose: 100 mg/day

Comments:
-The benefits of therapy should be weighed against the potential risks (e.g., chronic pulmonary reactions).

Use: For long-term suppressive therapy

Renal Dose Adjustments

Anuria, oliguria, or significant renal dysfunction (CrCl less than 60 mL/min or significantly elevated creatinine): Contraindicated

Liver Dose Adjustments

Data not available

Precautions

CONTRAINDICATIONS:
-Anuria, oliguria, or significant renal dysfunction (CrCl less than 60 mL/min or clinically significant elevated serum creatinine)
-Pregnant patients at term (38 to 42 weeks gestation), during labor and delivery, or when the onset of labor is imminent (because of possibility of hemolytic anemia due to immature erythrocyte enzyme systems [glutathione instability])
-Neonates younger than 1 month (because of possibility of hemolytic anemia due to immature erythrocyte enzyme systems [glutathione instability])
-History of cholestatic jaundice/hepatic dysfunction associated with this drug
-Known hypersensitivity to the active component

Capsules (macrocrystals) and oral suspension: Safety and efficacy have not been established in patients younger than 1 month.
Dual-release capsules (macrocrystals-monohydrate): Safety and efficacy have not been established in patients younger than 12 years.

Consult WARNINGS section for additional precautions.

Dialysis

This drug is dialyzable; however, no dose adjustment guidelines have been reported.

Other Comments

Administration advice:
-Capsules (macrocrystals) and oral suspension: Administer with food to improve drug absorption and, in some patients, tolerance.
-Dual-release capsules (macrocrystals-monohydrate): Administer with food.
-Oral suspension: Shake vigorously before administration; use within 30 days.

Storage requirements:
-Capsules (macrocrystals): Store at 20C to 25C (68F to 77F); dispense in tight, light-resistant container.
-Dual-release capsules (macrocrystals-monohydrate): Store at 15C to 30C (59F to 86F).
-Oral suspension: Store between 20C to 25C (68F to 77F), excursions permitted to 15C to 30C (59F to 86F); protect from freezing; avoid exposure to strong light.

General:
-This drug is not indicated for the treatment of pyelonephritis or perinephric abscesses.
-To reduce the development of drug-resistant organisms and maintain effective therapy, this drug should be used only to treat or prevent infections proven or strongly suspected to be caused by susceptible bacteria.
-Culture and susceptibility information should be considered when selecting/modifying antibacterial therapy or, if no data are available, local epidemiology and susceptibility patterns may be considered when selecting empiric therapy.
-Urine specimens for culture and susceptibility testing should be obtained before and after completion of therapy.
-Nitrofurantoins lack the broader tissue distribution of other therapeutic agents approved for UTIs; thus, many patients treated with this drug are predisposed to persistence/reappearance of bacteriuria. If persistence/reappearance of bacteriuria occurs after using this drug, other therapeutic agents with broader tissue distribution are recommended.
-When considering the use of this drug, lower eradication rates should be balanced against increased potential for systemic toxicity and antimicrobial resistance if agents with broader tissue distribution are used.
-Many patients who cannot tolerate the microcrystalline formulation are able to take the macrocrystals formulation without nausea.

Monitoring:
-Hepatic: For changes in biochemical tests that would indicate liver injury (periodically during therapy)
-Renal: For changes in renal function (periodically during long-term therapy); renal function in elderly patients
-Respiratory: Pulmonary condition (closely during long-term therapy)

Patient advice:
-Take with food, avoid missing doses, and complete the entire course of therapy.
-Consult physician if any unusual symptoms occur during therapy.
-Consult physician at once if watery and bloody stools (with or without stomach cramps and fever) develop.
-Do not use antacid preparations containing magnesium trisilicate while taking this drug.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.