Diltiazem-induced eosinophilic pleural effusion.

A 68-year-old woman developed eosinophilic pleural effusion and systemic eosinophilia 2 months after starting antihypertensive therapy with diltiazem. Several drugs are known to cause this disorder; however, the only other drug the patient had been taking was clonidine, which she had taken for the past 3-4 years. She was evaluated for all other possible causes of eosinophilia and eosinophilic pleural effusion, including malignancy, infection, and autoimmune disorders. Her symptoms resolved after diltiazem was discontinued, and no recurrence was noted on follow-up. To our knowledge, this is the first case report of eosinophilic pleural effusion caused by diltiazem. According to the Naranjo adverse drug reaction probability scale, a probable relationship existed between diltiazem and the patient's eosinophilia and pleural effusion. Although numerous drugs have been associated with eosinophilia and eosinophilic pleural effusion, the spectrum may actually be wider than is commonly thought and may include such unrecognized agents as diltiazem.