Nitrofurantoin is a prescription antibacterial medication specifically designed to treat and prevent urinary tract infections (UTIs) caused by susceptible strains of bacteria. It belongs to the nitrofuran class of antibiotics and works by inhibiting bacterial enzyme systems, disrupting cell wall synthesis, and interfering with DNA and RNA production. This targeted mechanism makes it particularly effective against common uropathogens like Escherichia coli, Enterobacter spp., Klebsiella spp., and some strains of Staphylococcus. Unlike broad-spectrum antibiotics, nitrofurantoin concentrates primarily in the urinary tract, minimizing disruption to gut flora and reducing the risk of systemic side effects. It is available in multiple formulations, including macrocrystals and monohydrate/macrocrystal combinations, to optimize absorption and tolerability.

Features

• Antibacterial agent specifically active against common uropathogens
• Available in immediate-release and extended-release oral formulations
• High urinary concentration with low systemic absorption
• Multiple dosage strengths: 50 mg, 100 mg capsules; 25 mg/5 mL suspension
• Compatible with most concomitant medications under guidance
• Requires prescription and medical supervision for use

Benefits

• Effectively eliminates bacteria causing lower urinary tract infections
• Reduces recurrence of UTIs when used prophylactically
• Minimizes impact on gastrointestinal flora compared to broad-spectrum antibiotics
• Convenient oral administration with or without food
• Suitable for both acute treatment and long-term prevention in indicated patients
• Well-established safety profile with decades of clinical use

Common use

Nitrofurantoin is primarily indicated for the treatment of acute uncomplicated urinary tract infections, including cystitis and pyelonephritis, caused by susceptible strains of bacteria. It is also prescribed for long-term suppressive therapy in patients with recurrent UTIs, particularly in postmenopausal women, patients with neurogenic bladder, or those requiring intermittent catheterization. The drug is not appropriate for systemic infections or infections outside the urinary tract due to its limited tissue penetration. Healthcare providers often select nitrofurantoin based on local antibiogram data and individual patient factors, including renal function and allergy history.

Dosage and direction

Dosage varies based on indication, formulation, and patient factors. For acute uncomplicated UTIs: 50-100 mg orally four times daily for 7 days, or 100 mg twice daily for extended-release formulations. For prophylaxis: 50-100 mg once daily at bedtime. Pediatric dosing is weight-based at 5-7 mg/kg/day divided into four doses. Administration with food or milk enhances absorption and reduces gastrointestinal upset. Capsules should be swallowed whole; the suspension must be shaken well before use. Dosage adjustment is necessary in patients with renal impairment (CrCl <60 mL/min), and the drug is contraindicated when CrCl <30 mL/min due to inadequate urinary concentration and increased toxicity risk.

Precautions

Patients should complete the full prescribed course even if symptoms resolve earlier to prevent resistance. Regular monitoring of renal and hepatic function is advised during prolonged therapy. Pulmonary reactions, including interstitial pneumonitis and fibrosis, may occur with long-term use, requiring immediate evaluation of new respiratory symptoms. Hemolytic anemia may develop in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Peripheral neuropathy, though rare, has been reported and may become irreversible if not promptly addressed. Use during pregnancy requires careful risk-benefit assessment, particularly near term due to neonatal hemolysis risk.

Contraindications

Nitrofurantoin is contraindicated in patients with known hypersensitivity to nitrofurantoin or other nitrofuran derivatives. It must not be used in patients with significant renal impairment (CrCl <30 mL/min or on dialysis) due to inadequate efficacy and increased toxicity. Contraindications include a history of nitrofurantoin-associated hepatic dysfunction or cholestatic jaundice. The drug is not recommended for infants under one month old due to immature enzyme systems and potential hemolytic risk. Patients with pre-existing peripheral neuropathy should avoid nitrofurantoin unless no alternatives exist.

Possible side effect

Common side effects include nausea, vomiting, abdominal pain, diarrhea, and headache, often diminishing with continued use. Less frequently, patients may experience pulmonary reactions (cough, dyspnea, chest pain), hypersensitivity reactions (rash, pruritus, urticaria), or hepatic effects (elevated transaminases, hepatitis). Rare but serious adverse effects include hemolytic anemia (especially in G6PD deficiency), peripheral neuropathy, Clostridioides difficile-associated diarrhea, and opportunistic infections. Patients should seek immediate medical attention for signs of severe reactions, such as jaundice, dark urine, respiratory distress, or neurological symptoms.

Drug interaction

Nitrofurantoin may interact with drugs that affect renal excretion, such as probenecid, which can inhibit urinary secretion and reduce efficacy. Concomitant use with magnesium trisilicate-containing antacids may decrease absorption. Drugs that cause hemolysis (e.g., sulfonamides) should be used cautiously in susceptible patients. Nitrofurantoin may antagonize the bactericidal effects of quinolones in vitro, though clinical significance is uncertain. It can reduce the efficacy of live bacterial vaccines; consult guidelines for appropriate intervals. Always inform healthcare providers of all concomitant medications, including OTC products and supplements.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next dose. In that case, skip the missed dose and resume the regular schedule. Doubling doses to compensate for a missed dose is not recommended, as it may increase the risk of adverse effects. Patients on prophylactic regimens should maintain consistent timing to ensure continuous urinary antibacterial levels. Setting reminders or using pill organizers can help improve adherence.

Overdose

Acute overdose may exacerbate common side effects, particularly gastrointestinal distress. There is no specific antidote; management involves symptomatic and supportive care, including gastric lavage if ingestion was recent. Hemodialysis is not effective due to nitrofurantoin’s rapid metabolism and protein binding. Patients should seek immediate medical attention or contact a poison control center for guidance. Chronic overdose may lead to toxicities such as hepatic injury or pulmonary reactions, requiring discontinuation and appropriate medical management.

Storage

Store at controlled room temperature (20-25°C or 68-77°F), protected from light and moisture. Keep the container tightly closed, and do not transfer capsules to other containers. Suspension formulations should not be frozen and must be discarded after the expiration date or within the specified days after reconstitution. Keep all medications out of reach of children and pets. Do not flush unused medication; dispose of properly through take-back programs or following local guidelines.

Disclaimer

This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting, changing, or stopping any medication. Individual patient needs may vary based on health status, comorbidities, and other factors. The prescribing physician should be the primary source of guidance regarding nitrofurantoin therapy.

Reviews

Clinical studies and decades of use support nitrofurantoin’s efficacy and safety for uncomplicated UTIs. Many healthcare providers appreciate its targeted spectrum and low resistance rates. Patient reviews often note effective symptom relief within 24-48 hours, though some report gastrointestinal side effects. Long-term users on prophylaxis frequently describe reduced UTI frequency with manageable side effects. Ongoing research continues to evaluate its role in antimicrobial stewardship programs.