• One of the most common drug-induced pulmonary diseases
  • Toxicity occurs in <1% of all users of drug


  • Acute Nitrofurantoin Toxicity: unclear mechanism (studies have shown prolonged lymhocyte transformation factor and migration inhibition factor production)
  • Chronic Nitrofurantoin Toxicity: induction of oxygen radicals by parenchymal cells

Pathologic Patterns

  • Acute Nitrofurantoin Toxicity: proliferation of fibroblasts/lymhoplasmocytic infiltrate (IgA-laden plasma cells)/DIP-like features
    • Importantly, absence of eosinophilia in lung tissue (despite peripheral eosinophilia)
  • Chronic Nitrofurantoin Toxicity: mimics idiopathic pulmonary fibrosis

Adverse Effects

Pulmonary Adverse Effects

Acute Nitrofurantoin Toxicity (see Drug-Induced Pulmonary Eosinophilia, Pneumonia, Interstitial Lung Disease-Etiology, and Pleural Effusion-Exudate)

  • Epidemiology
    • Onset: few hrs to several days after initiation of nitrofurantoin
    • Incidence is 1 in 550-5400
    • More common in females (possibly due to increased use of drug in females for UTI’s)
    • Not dose-related (can occur after single dose)
  • Diagnosis
    • CBC: peripheral leukocytosis and eosinophilia (33% of cases)
    • Elevated ESR (50% of cases)
    • CXR/Chest CT
      • Basilar-predominant alveolar and/or interstitial infiltrates: may be unilateral or asymmetric
      • Pleural Effusion: usually unilateral
        • 20% of acute cases have infiltrate with effusion
        • 3% of acute cases have isolated effusion
    • PFT’s: obstruction
    • Pleural Fluid: may demonstrate pleural eosinophilia in some cases
  • Clinical
    • Fever (usually present)
    • Dyspnea (usually present)
    • Cough (66% of cases)
    • Bronchospasm (see Obstructive Lung Disease): may occur in the absence of parenchymal or pleural manifestations in some cases
    • Pleuritic Chest Pain (33% of cases)
    • Rales (most cases)
  • Treatment
    • Supportive care
    • Not clear that corticosteroids are effective -> probably not indicated
    • Re-challenge is contraindicated

Chronic Nitrofurantoin Toxicity (see Pneumonia, Interstitial Lung Disease-Etiology, and Pleural Effusion-Exudate)

  • Epidemiology
    • Chronic nitrofurantoin toxicity is less common than acute nitrofurantoin toxicity
    • Onset: 6 months-years after start of continuous or intermittent use of nitrofurantoin
    • More common in females
  • Diagnosis
    • CXR/Chest CT
      • Diffuse interstitial infiltrates
      • Pleural Effusion: 10% of chronic cases have effusion (no chronic cases have effusion without infiltrates)
    • PFT’s: restriction without obstruction
    • FOB-BAL: lymphocytosis
    • OLB: inflammatory cells and fibrosis
  • Clinical
    • Fever and eosinophilia are less common than in acute toxicity
    • Insidious onset of fever and cough
  • Treatment
    • Withdraw Nitrofurantoin: wait 2-4 mo to see if resolves (by CT + PFT’s) without steroids -> if not, then initiate a trial of corticosteroids

Drug-Induced SLE (see Systemic Lupus Erythematosus)

  • Few reported cases: present with pleuropulmonary disease with positive ANA

Cryptogenic Organizing Pneumonia (see Cryptogenic Organizing Pneumonia and Lung Nodule or Mass)

  • May appear as nodular infiltrates

Acute Lung Injury-ARDS (see Acute Lung Injury-ARDS)

Other Adverse Effects


  • 71% of all reactions are severe enough to require hospitalization
  • 1% of all cases were fatal: 4/49 with chronic fibrosis toxicity and 2/398 with acute toxicity


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