A 64-year-old female patient with rheumatoid arthritis (RA) developed cough, expectoration, and shortness of breath 9 months after adjusting her long-term antirheumatic regimen to hydroxychloroquine sulfate, iguratimod, and methylprednisolone. Chest CT revealed newly emerged pulmonary lesions. Following initial and intensified anti-infective therapy, the symptoms showed no improvement, with persistent lesion progression and no definitive identification of causative microorganisms through etiological tests. Following a multidisciplinary consultation, the patient was diagnosed with drug-induced organizing pneumonia, with iguratimod suspected as the probable causative agent. After discontinuing iguratimod and initiating glucocorticoid therapy, the patient's respiratory symptoms gradually resolved. Chest CT scan showed complete resolution of pulmonary lesions after one month. Naranjo's Assessment Scale was used to evaluate the association between iguratimod and organizing pneumonia, the result was “possible”. Drug-induced lung injury caused by iguratimod is rarely reported. This case highlights the importance of remaining vigilant for drug-induced lung injury risk during clinical use of iguratimod. It is advisable to monitor patients for respiratory symptoms throughout treatment and to conduct regular chest CT scans and pulmonary function tests to enable early detection and timely intervention.

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