Nitrofurantoin

Nitrofurantoin is a prescription antibacterial medication specifically indicated for the treatment and prophylaxis of uncomplicated urinary tract infections (UTIs) caused by susceptible strains of Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, and certain strains of Klebsiella and Enterobacter species. As a nitrofuran derivative, it exerts its bactericidal effect by interfering with bacterial enzyme systems and cell wall synthesis. Its unique pharmacokinetic profile results in high concentrations in the urine and renal tissue, while achieving minimal systemic absorption, making it particularly suitable for lower urinary tract infections. Healthcare providers frequently prescribe nitrofurantoin due to its targeted action and generally favorable safety profile when used appropriately.

Features

• Contains nitrofurantoin as the active pharmaceutical ingredient
• Available in immediate-release capsules (25 mg, 50 mg, 100 mg) and macrocrystalline formulations (100 mg)
• Specifically concentrates in urinary tract tissues
• Bactericidal against common UTI pathogens
• Multiple dosage forms including oral suspension
• Typically prescribed as a 5-7 day course for acute infections
• Some formulations may be prescribed for long-term prophylaxis

Benefits

• Effectively eliminates susceptible bacteria causing urinary tract infections
• Reduces recurrence of UTIs when used prophylactically
• Minimal impact on gut flora compared to broad-spectrum antibiotics
• Lower risk of developing bacterial resistance compared to some other antibiotic classes
• Rapid relief from UTI symptoms when treatment is initiated promptly
• Well-established safety profile with decades of clinical use

Common use

Nitrofurantoin is primarily prescribed for the treatment of acute uncomplicated lower urinary tract infections, including cystitis, caused by susceptible strains of bacteria. It is particularly effective against E. coli, which accounts for approximately 75-90% of community-acquired UTIs. The medication is also commonly used for long-term suppression therapy in patients with recurrent UTIs, typically at a reduced dosage taken once daily at bedtime. Healthcare providers may prescribe nitrofurantoin prophylactically for patients undergoing urological procedures or those with anatomical abnormalities predisposing them to frequent infections. It is not indicated for the treatment of pyelonephritis or perinephric abscesses due to inadequate tissue penetration in the renal cortex.

Dosage and direction

For acute uncomplicated UTIs in adults and children ≥12 years: 50-100 mg four times daily with food or milk for 7 days, or 100 mg twice daily for 5 days (depending on formulation). For long-term prophylaxis: 50-100 mg once daily at bedtime. Pediatric dosing for children ≥1 month: 5-7 mg/kg/day divided into four doses, not to exceed 400 mg daily. Administration with food enhances absorption and reduces gastrointestinal upset. The macrocrystalline formulation may be taken with or without food. Patients should complete the full course of therapy even if symptoms improve earlier. Dosage adjustment is required in patients with renal impairment (CrCl <60 mL/min).

Precautions

Nitrofurantoin should be used with caution in patients with renal impairment (CrCl <60 mL/min) due to reduced efficacy and increased risk of toxicity. Monitor for pulmonary reactions, which may occur acutely or develop insidiously with long-term use. Periodic liver function tests are recommended during prolonged therapy. Hemolytic anemia may occur in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Use cautiously in elderly patients due to increased risk of adverse reactions. May cause tooth discoloration (yellow-brown) in pediatric patients. Peripheral neuropathy, which may become severe or irreversible, has been reported. Discontinue immediately if neurological symptoms develop.

Contraindications

Patients with known hypersensitivity to nitrofurantoin or other nitrofuran derivatives. Significant renal impairment (creatinine clearance <60 mL/min) due to inadequate drug concentration in urine and increased systemic exposure. Infants younger than one month due to risk of hemolytic anemia. Pregnancy at term (38-42 weeks gestation) and during labor and delivery due to risk of hemolytic anemia in the neonate. Patients with history of cholestatic jaundice or hepatic dysfunction associated with previous nitrofurantoin use. Those with history of nitrofurantoin-associated pulmonary reactions.

Possible side effect

Common: nausea (occurring in up to 8% of patients), headache, flatulence, and abdominal pain. Less frequent: vomiting, diarrhea, drowsiness, and dizziness. Serious but rare: pulmonary reactions (including interstitial pneumonitis and pulmonary fibrosis), hepatic reactions (hepatitis, cholestatic jaundice), peripheral neuropathy, hemolytic anemia (especially in G6PD deficiency), and Clostridium difficile-associated diarrhea. Hypersensitivity reactions including angioedema, urticaria, and anaphylaxis may occur. Superinfections with resistant organisms including fungi may develop. Skin reactions ranging from mild rash to Stevens-Johnson syndrome have been reported.

Drug interaction

Antacids containing magnesium trisilicate may reduce nitrofurantoin absorption and efficacy. Probenecid and sulfinpyrazone may inhibit renal tubular secretion of nitrofurantoin, increasing serum levels and toxicity risk while decreasing urinary concentrations. Drugs that cause renal impairment may alter nitrofurantoin excretion. May diminish the efficacy of live bacterial vaccines (BCG vaccine, typhoid vaccine). Concurrent use with other drugs known to cause pulmonary toxicity may increase risk of pulmonary reactions. Neurotoxic drugs may potentiate the risk of peripheral neuropathy.

Missed dose

If a dose is missed, take it as soon as remembered unless it is almost time for the next scheduled dose. Do not double the dose to make up for a missed dose. Maintain regular dosing intervals to ensure consistent therapeutic urinary concentrations. If multiple doses are missed, contact healthcare provider for guidance. For prophylactic regimens, resume regular schedule with the next dose.

Overdose

Symptoms may include nausea, vomiting, and dizziness. No specific antidote exists. Management involves symptomatic and supportive care, including gastric lavage if ingestion was recent. Adequate hydration should be maintained to promote urinary excretion. Hemodialysis may be of limited value due to nitrofurantoin’s rapid elimination and protein binding characteristics. Monitor for potential complications including neurotoxicity and hematological abnormalities. Contact poison control center or emergency medical services immediately for guidance.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) in the original container. Protect from light and moisture. Keep tightly closed. Do not store in bathroom or other humid areas. Keep out of reach of children and pets. Do not use after expiration date printed on packaging. Do not transfer capsules to other containers as this may affect stability. Suspension formulations should be shaken well before use and discarded after the prescribed treatment course is completed.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting, changing, or stopping any medication. The prescribing physician should be aware of the patient’s complete medical history, current medications, and allergies. Individual response to medication may vary. Proper diagnosis and treatment selection should be made by a healthcare provider familiar with the patient’s specific condition.

Reviews

Clinical studies demonstrate nitrofurantoin’s efficacy in treating uncomplicated UTIs with success rates of 85-95% for susceptible organisms. Many urologists consider it a first-line option for acute cystitis and long-term prophylaxis. Patients generally report symptom improvement within 24-48 hours of initiation. Some reviews note gastrointestinal side effects as the most common reason for discontinuation. Long-term safety data support its use for prophylaxis with appropriate monitoring. Recent surveillance data indicate maintained susceptibility among common uropathogens in many regions, though resistance patterns vary geographically.