Nitrous oxide, more commonly known as laughing gas, is often used as a conscious sedative during a dental visit. The gas is administered with a mixture of oxygen and has a calming effect that helps phobic or anxious patients relax during their dental treatment. Because it is a mild sedative, patients are still conscious and can talk to their dentist during their visit. After treatment, the nitrous is turned off and oxygen is administered for a few minutes to help flush any remaining gas. The effects wear off almost immediately. Nitrous oxide rarely has side effects, although some patients may experience minor nausea and constipation.