The urinary antiseptic nitrofurantoin (NF) commonly causes pulmonary reactions (PMID 891588). Most commonly, dyspnea, fever and chest pain occur acutely after few days-to-one or two weeks on the medication, sometimes in the context of moderat eosinophilia, to resolve in a few days off the drug. Less often, NF is associated with subacute chronic interstitial pneumonitis mimicking BOOP or pulmonary fibrosis. Autoimmunity can be present in the form of ANA or ANCA antibodies. Risk increases if renal failure present (PMID 23660771)