Aprepitant is used with other medications in adults and children 6 months of age and older to prevent nausea and vomiting that may occur after receiving cancer chemotherapy treatment. It is also used with other medications in adults and children 6 months of age and older to prevent delayed nausea and vomiting that may occur several days after receiving certain chemotherapy medications. Aprepitant is not used to treat nausea and vomiting that you already have. Aprepitant is in a class of medications called antiemetics.