Excipients in valproic acid syrup may cause diarrhea: a case report. A 5-year-old child receiving valproic acid syrup for seizure control developed diarrhea probably from the excipient ingredients. Each 5 mL of valproic acid syrup contains sucrose 3 g, glycerin 0.75 g, and sorbitol 0.75 g, providing daily amounts of 36, 9, and 9 g of sucrose, glycerin, and sorbitol, respectively. The diarrhea resolved when the child was switched to another valproic acid product. Clinicians should be aware of potential problems that may occur from excipient ingredients in pharmaceutical products when evaluating adverse effects of medications. 