Nitrous oxide, sometimes referred to as “laughing gas,” is an effective and safe sedation agent that is inhaled through a mask that fits over your nose to help you relax. Mixed with oxygen, Nitrous oxide allows you to breathe normally through your nose and within minutes you should start to feel the effects. You may feel light-headed or a tingling in your arms and legs. Some patients comment that their legs and arms feel heavy. Ultimately, you should feel comfortable and calm. The effects of nitrous oxide wear off quickly after the small mask is removed.