RESUMO
Nitrofurantoin is considered optimal treatment for acute uncomplicated cystitis by the Infectious Diseases Society of America and is being increasingly recommended due to microbial resistance to sulfamethoxazole/trimethoprim and various fluoroquinolone antibiotics. Adverse effects of nitrofurantoin are generally considered mild, with gastrointestinal complaints being the most common. However, there have been isolated case reports describing a more severe systemic inflammatory response syndrome-like reaction, which leads to diagnostic challenges and treatment complications. We report the case of a patient with repeat episodes of systemic inflammatory response syndrome secondary to nitrofurantoin, which was initially attributed to recurrent urinary tract infections.