Onsita 4 mg Tablets contain ondansetron, an antiemetic medication used to prevent and treat nausea and vomiting caused by chemotherapy, radiation therapy, and surgery. Each pack contains 10 tablets./Description: Onsita (ondansetron) is a selective 5-HT3 receptor antagonist that works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting. It is used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery.. Please Note that product description, color, ingredients, package and other information maybe different from the original pack kindly check the product for more accurate details.