Nitrofurantoin is a nitrofuran-class antibiotic that has been in clinical use since the 1950s, primarily for the treatment and prevention of urinary tract infections (UTIs). It works by being reduced inside bacterial cells into reactive intermediates that damage DNA, ribosomal proteins, and other macromolecules. This multi-target mechanism contributes to its broad activity against common urinary pathogens, including Escherichia coli, Enterococcus faecalis, and some strains of Klebsiella and Staphylococcus saprophyticus. Resistance is relatively uncommon compared to other oral antibiotics, making nitrofurantoin a reliable option in an era of increasing antimicrobial resistance.
Unlike many systemic antibiotics, nitrofurantoin achieves therapeutic concentrations only in urine, as it is rapidly excreted by the kidneys. This property makes it ineffective for systemic infections or complicated pyelonephritis but highly effective for bladder infections (cystitis). The drug is absorbed well orally, and newer formulations like nitrofurantoin monohydrate/macrocrystals (Macrobid) provide sustained urinary concentrations with better gastrointestinal tolerability compared to older microcrystalline forms.
Nitrofurantoin is recommended as a first-line therapy for acute uncomplicated cystitis in many clinical guidelines, including those in Europe and North America. Its role extends to prophylaxis for recurrent UTIs, especially in women, where low nightly doses have proven safe and effective. Nevertheless, its long-term use requires careful monitoring due to rare but serious adverse effects such as pulmonary toxicity, hepatotoxicity, and neuropathy.
Most side effects are reversible if the drug is stopped promptly. Monitoring is essential during long-term prophylaxis.
Patients should be educated on warning signs (shortness of breath, persistent cough, jaundice, numbness/tingling) and instructed to seek care urgently if they arise.
Patients should provide a complete list of prescription, OTC, and herbal products before starting nitrofurantoin.
Overdose: Rare, usually presents with gastrointestinal upset, headache, dizziness. Severe cases may involve neuropathy or pulmonary reactions. Management is supportive—activated charcoal may be given if recent ingestion, with close monitoring of renal and hepatic function.
Accidental double dose: Typically not harmful but may cause transient nausea or dizziness. Skip the next scheduled dose if within a few hours and resume regular timing. Do not take extra tablets to compensate.
Missed dose: Take as soon as remembered unless close to the next scheduled dose. Never double up doses.
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