A78-21 When Treatment Turns Toxic: A Case of Nitrofurantoin-induced Interstitial Lung Disease

Abstract Introduction Nitrofurantoin is an antibiotic very commonly used to treat and prevent lower UTIs. Common adverse effects include gastrointestinal upset, headache, and hypersensitivity reactions. Rare but serious adverse events involve hepatotoxicity, peripheral neuropathy, and pulmonary toxicity. Nitrofurantoin-induced pulmonary toxicity (NIPT) is a well-recognised but infrequent complication, typically manifesting within days to weeks of exposure, presenting with fever, cough, dyspnea, and diffuse pulmonary infiltrates. Pulmonary toxicity in its acute form is seen in 1 in 5,000 users, while chronic pulmonary injury is seen in 1 in 750 users. This report describes a rare and life-threatening case of NIPT, highlighting the diagnostic challenges and emphasizing the importance of early recognition. Case Description An 82-year-old woman with a history of interstitial lung disease and recurrent urinary tract infections over the past five years, requiring multiple courses of nitrofurantoin, presented with worsening dyspnea and productive cough one week after restarting nitrofurantoin for a recurrent UTI. She had recently recovered from COVID-19 pneumonia diagnosed one month prior. Her inpatient symptoms progressed from mild respiratory distress to a persistent cough and continuous oxygen dependence, accompanied by rigors and low-grade fever.Initial chest radiography demonstrated bilateral patchy opacities and ground-glass changes. Laboratory evaluation ruled out infectious and cardiac etiologies. Histopathologic analysis revealed findings consistent with nonspecific interstitial pneumonia and giant cell interstitial pneumonia.Nitrofurantoin was promptly discontinued, and treatment with mycophenolate mofetil and a prednisone taper was initiated. The patient exhibited rapid clinical and radiologic improvement following therapy and has remained in remission since. Discussion NIPT manifests as acute, subacute, or chronic interstitial pneumonitis with a different mechanism of inflammation. The acute form results from a type III hypersensitivity reaction, whereas direct oxidative stress-mediated fibrosis leads to chronic injury. This case illustrates an overlap of NIPT on underlying pulmonary injury secondary to COVID pneumonia, chronic hypoxic respiratory failure, and Interstitial lung disease. NIPT typically affects patients above the age of 60; heightened awareness is essential to facilitate timely recognition and discontinuation of nitrofurantoin, preventing misdiagnosis as pneumonia, acute respiratory distress syndrome, or heart failure, which may lead to unnecessary interventions such as intubation while the offending drug is continued. Conclusion This case uniquely highlights the quick progression of respiratory distress to life-threatening hypoxemia after a short-term exposure to nitrofurantoin while drawing attention to the importance of distinguishing it from other preexisting pulmonary pathologies contributing to respiratory distress. It also accentuates the importance of early diagnosis in the successful reversal of symptoms and improving outcomes. This abstract is funded by: None