When Clopidogrel Reaches the Lung: A Case of Diffuse Interstitial Lung Disease

Drug-induced diffuse interstitial lung diseases are uncommon but potentially severe adverse reactions. Clopidogrel, a widely used antiplatelet agent for the prevention of thromboembolic events, has only rarely been associated with interstitial lung injury. We report the case of a 76-year-old former smoker with a history of dyslipidemia and triple-vessel coronary artery disease who was admitted for chest pain following a recent myocardial infarction. Coronary angiography revealed no new coronary lesions, and antiplatelet therapy was switched from ticagrelor to clopidogrel. Three days after clopidogrel initiation, the patient developed progressive dyspnea (New York Heart Association: NYHA class III), hypoxemia (partial pressure of oxygen or PaO₂, 58 mmHg), bilateral crackles, and diffuse interstitial lung involvement with bilateral ground-glass opacities on chest imaging. Infectious, thromboembolic, and other potential etiologies were excluded. Given the close temporal relationship between symptom onset and clopidogrel exposure, together with the exclusion of alternative causes, clopidogrel-induced diffuse interstitial lung disease was suspected. Discontinuation of clopidogrel led to rapid clinical, biological, and radiological improvement within three days. Drug causality assessment was considered probable according to the Bégaud method (C2S2, intrinsic score I3). Although generally well tolerated, clopidogrel should be recognized as a rare but potentially serious cause of reversible diffuse interstitial lung disease. Early recognition and prompt withdrawal of the offending drug may result in rapid recovery and help avoid unnecessary investigations and treatments.