Fatalities have been reported. Patients receiving long-term therapy should be monitored periodically for changes in renal function. If numbness or tingling occurs, discontinue use. Cases of hemolytic anemia of the primaquine sensitivity type have been induced by nitrofurantoin. Any sign of hemolysis is an indication to discontinue the drug.
Hemolysis ceases when the drug is withdrawn.
Pseudomonas is the organism most commonly implicated in superinfections in patients with nitrofurantoin preparations. Nitrofurantoin was not carcinogenic when fed to female Holtzman rats for 44.5 weeks or to female Sprague-Dawley rats for 75 weeks. Two chronic rodent bioassays utilizing male and female Sprague-Dawley rats and 2 chronic bioassays in Swiss mice and BDF1 mice revealed no evidence of carcinogenicity. Nitrofurantoin has demonstrated mutagenic potential in a variety of laboratory assays conducted in vitro with mammalian and non-mammalian cells exposed to therapeutically attainable and higher concentrations. Point and possibly other types of mutations were observed in bacteria, yeast and fungi.