Valproic acid-induced eosinophilic pleural effusion: An uncommon occurrence

A 43-year-old male using valproic acid (VA) for 2 years for seizure disorder presented with right-sided moderate pleural effusion. Pleural fluid analysis revealed exudative effusion with 42% eosinophils. There was no evidence of haemothorax, pneumothorax, malignancy, and parasitic infections. Suspecting a drug-related event, VA was discontinued. The patient showed clinical improvement with resolution of pleural effusion on chest radiograph three weeks later. VA is a popular drug used for variety of disorders like seizures, migraines, and schizophrenia. There is a paucity of literature on VA-induced pleural effusion. Though a rare phenomenon, clinicians should be aware of such a possibility to avoid erroneous diagnosis.