Emadon orally disintegrating tablet is used to prevent nausea and vomiting caused by certain medical treatments. These treatments include: -chemotherapy. -radiation treatment. -surgery. It contains Ondansetron which belongs to a class of drugs called antiemetics. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions. Antiemetics are drugs that reduce nausea and vomiting. Ondansetron works by blocking the release of the chemical serotonin in the gut and the central nervous system. This keeps serotonin from causing nausea and vomiting.