Methylphenidate causes chronic eosinophilic pneumonia.

A man who is 38 years old and diagnosed with attention-deficit hyperactivity disorder was prescribed methylphenidate. Three weeks later, he began experiencing progressive shortness of breath and coughing. Imaging of his chest showed patchy bilateral ground-glass opacities, and bronchoscopy revealed a 15% eosinophil count in his bronchoalveolar lavage. A transbronchial biopsy confirmed a diagnosis of eosinophilic pneumonia. The patient's condition improved when he was given steroids and stopped taking methylphenidate. However, he developed the same symptoms again a few days after restarting the medication, along with a skin rash. This strongly suggests that methylphenidate was the cause of his eosinophilic pneumonia.