Valproic acid-induced eosinophilic pleural effusion: a case report and review of the literature.

We present a case of eosinophilic pleural effusion due to valproic acid (VPA), a rare adverse event that has been reported previously. A 30-year-old male patient presented with respiratory symptoms and right-sided pleuritic pain, within days of initiation of VPA treatment for a generalized seizure. Chest radiography revealed a moderate-sized right-sided pleural effusion, which was an exudate with a pH of 7.54 and 48% eosinophils. Symptoms resolved soon after discontinuation of the drug, as did the effusion in a repeat radiograph 3 weeks later. The likelihood that VPA was the cause of the effusion is examined.