[16] Common side effects include nausea, loss of appetite, diarrhea, and headaches.

[22][23] The efficacy of nitrofurantoin in treating UTIs combined with a low rate of bacterial resistance to this agent makes it one of the first-line agents for treating uncomplicated UTIs as recommended by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases.

[28] Nitrofurantoin is not recommended for the treatment of pyelonephritis (kidney infection),[24] and intra-abdominal abscess,[29] because of extremely poor tissue penetration and low blood levels.

[33] In any case, in men with antibiotic-refractory or relapsing chronic bacterial prostatitis, prophylactic nitrofurantoin may be useful in preventing UTIs and managing symptoms.

[3] Newborns of women given this drug late in pregnancy had a higher risk of developing neonatal jaundice.

[41] Nitrofurantoin is contraindicated in patients with decreased renal function (CrCl < 60 ml/min) due to systemic accumulation and subtherapeutic levels reached in the urinary tract.

Nitrofurantoin is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency (G6PD) because of risk of intravascular hemolysis resulting in anemia.

[44][45] These reactions usually develop 3–8 days after the first dose of nitrofurantoin, but may occur from a few hours to a few weeks after starting the drug.

Chest radiograph will often show unilateral or bilateral infiltrates similar to pulmonary edema.

[9] This uncommon reaction may occur 1 month to 6 years after starting the drug and is usually related to its total lifetime dose.

[50] Similarly to other antibiotics, nitrofurantoin has been associated with increased risk of Clostridioides difficile infection and associated diarrhea.

[53] However, subsequent clinical studies failed to replicate these findings and the earlier results have been deemed erroneous.

In studies of dogs, the majority of urinary excretion is through glomerular filtration with some tubular secretion.

[56] Nitrofurantoin is concentrated in the urine, leading to higher and more effective levels in the urinary tract than in other tissues or compartments.

The broad mechanism of action for nitrofurantoin is likely responsible for the low development of resistance to its effects, as it affects many different processes important to the bacterial cell.

[59] Residues from the breakdown of nitrofuran veterinary antibiotics, including nitrofurantoin, have been found in chicken in Vietnam, China, Brazil, and Thailand.

[60] The European Union prohibited the use of nitrofurans in food producing animals by classifying it in ANNEX IV (list of pharmacologically active substances for which no maximum residue limits can be fixed) of the Council Regulation 2377/90.

Japan did not allocate MRLs for nitrofurans leading to the implementation of a "zero tolerance or no residue standard".

The Ministry of Agriculture and Cooperatives had already prohibited importation and use of furazolidone and nitrofurazone in animal feed in 1999 which was extended to all nitrofurans in 2002.

Several metabolites of nitrofurans, such as furazolidone, furaltadone and nitrofurazone cause cancer or genetic damage in rats.