Differential Dx includes anaphylaxis, pneumonia
The differential diagnosis for nitrofurantoin-induced lung disease includes anaphylaxis, asthma, bronchitis, and pneumonia. Drug anaphylaxis typically occurs within hours of administration and often has skin findings of urticaria, pruritus, and angioedema of the oral mucosa. Patients may present with dyspnea, wheezing, stridor, hypoxemia, and respiratory distress.8
Although asthma, bronchitis, and pneumonia can present with a fever, cough, and radiograph findings, they are not usually associated with a rash. Identifying and removing the offending agent—a medication—is key in differentiating this disease from other common lung ailments.
Stop the offending agent, consider corticosteroids
Immediately discontinuing nitrofurantoin is usually sufficient to resolve the symptoms of acute nitrofurantoin-induced lung disease, often within 24 to 48 hours. Chest radiograph and PFT changes resolve within weeks of discontinuation. (Reintroducing nitrofurantoin to the patient will produce similar symptoms with a more rapid onset.) Corticosteroids are often used to treat this lung injury, although their effectiveness remains unproven.
With the chronic reaction, nitrofurantoin therapy is stopped and most patients are started on corticosteroids, typically dosed at 20 to 40 mg per day with a prolonged taper over several months. With treatment, many patients recover from their chronic pulmonary reaction, although it may take months to years.3 Some patients may never fully recover and continue to have symptoms, radiographic findings, and PFT changes characteristic of pulmonary fibrosis.
More seriously, nitrofurantoin-induced lung disease may require hospitalization. Rare cases have required lung transplantation and others have resulted in death due to respiratory failure.1
A speedy recovery for our patient
We told our patient to discontinue the nitrofurantoin, and we opted not to start her on corticosteroids. Her symptoms resolved within 3 days of discontinuing the medication, and she had no return of her UTI symptoms. Her rash also resolved within 5 days.
CORRESPONDENCE: Drew C. Baird, MD, Department of Family and Community Medicine, Carl R. Darnall Army Medical Center, 36000 Darnall Loop, Fort Hood, TX 76544; drew.baird@us.army.mil