A patient on chronic nitrofurantoin therapy may develop a lung injury that has an insidious onset and that can be fatal if misdiagnosed.


Clinical setting: long-term nitrofurantoin therapy (minimum 10 months, up to several years) for the prevention of recurrent urinary tract infections, typically in the elderly and often in women


Clinical features:

(1) persistent cough

(2) increasing dyspnea

(3) bilateral changes in lung imaging studies (usually interstitial infiltrates on chest X-ray, or ground glass opacities on CT scan)

(4) usually abnormal pulmonary function tests (may be normal in early or mild disease)


A lung biopsy may be show nonspecific changes or show varying degrees of interstitial fibrosis with chronic inflammation.


The clinical changes may be ascribed to:

(1) pre-existing COPD

(2) pre-existing asthma or hypersensitivity

(3) lung injury caused by another drug

(4) rheumatologic condition

(5) other lung disease


Reversal of respiratory symptoms and the pulmonary infiltrate on discontinuation of therapy is the key diagnostic and therapeutic intervention.


Patients with severe disease may benefit from corticosteroid therapy.


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