If you are a patient that has dental anxiety nitrous oxide may be a good option for you. Nitrous oxide is a safe and effective sedative agent that is mixed with oxygen and inhaled through a small mask that fits over your nose to help you relax. Nitrous oxide slows down your brain and your body's responses, and the effects of the drug varies depending on how much has been inhaled. Taking nitrous oxide can cause: feelings of euphoria, relaxation and calmness. fits of giggles and laughter – hence the nickname 'laughing gas' Nitrous oxide, sometimes called “laughing gas,” is one option your dentist may offer to help make you more comfortable during certain procedures.