Ondansetron is an anti-emetic used in the treatment of nausea and vomiting. Ondansetron is often following chemotherapy. Ondansetron is believed to be effective on both peripheral and central nerves. Ondansetron has the capability of reducing the activity of the vagus nerve that would further deactivate the vomiting center in the medulla oblongata and also blocks serotonin receptors. Ondansetron has no effect on the dopamine receptors or muscarinic receptors.