The benefits of nitrous oxide are many. The gas is administered with a comfortable mask placed over the nose, and the patient is instructed to breathe in through the nose and out through their mouth. As a precaution, patients should not eat anything for about two hours prior to use of the gas. The patient begins to feel a pleasant level of sedation anywhere from 30 seconds to three or four minutes. The cheeks and gums will also begin to feel numb in about a third of the patients.