Nitrofurantoin pulmonary toxicity.

An elderly woman taking 50 mg of nitrofurantoin daily for six months for suppression of recurrent urinary tract infections developed increasing dyspnea and bilateral pulmonary infiltrates. An open-lung biopsy confirmed diffuse interstitial fibrosis consistent with chronic nitrofurantoin pulmonary reaction. A chronic disabling respiratory illness persists in this person 10 months after discontinuing nitrofurantoin. Nitrofurantoin produces adverse pulmonary reactions more commonly than any other antimicrobial. There is an acute and a chronic form of pulmonary reaction to nitrofurantoin. Each is thought to result from a separate immunologic and/or toxic injury to the lung. Both the acute and chronic form can rarely result in fatal pulmonary reactions. Physicians must maintain a high index of suspicion for adverse reaction to nitrofurantoin, particularly in the elderly in whom declining renal function may lead to inadvertent toxic accumulations. Use of alternative antimicrobial agents with higher benefit-to-risk ratios for treatment of urinary tract infections should be considered. Persons suffering serious adverse reactions to nitrofurantoin should carry written warnings about reexposure.