Nitrous oxide, commonly known as "laughing gas," is a colorless, non-flammable gas with anesthetic and analgesic properties. It has a long-standing history of use in dentistry and minor medical procedures, primarily for its anxiolytic (anxiety-reducing), sedative, and analgesic effects. The anxiolytic properties of nitrous oxide are scientifically validated, primarily for acute anxiety, such as procedural or dental anxiety, rather than chronic anxiety disorders.

Several clinical studies have demonstrated that inhaled nitrous oxide is effective at reducing anxiety levels in patients undergoing minor surgical or dental procedures. Its mechanism is believed to involve modulation of GABAergic and NMDA receptor activity in the brain, leading to mild sedation and reduced anxiety. A 2015 study published in "Biological Psychiatry" also explored nitrous oxide as a potential rapid-acting treatment for treatment-resistant depression, which often co-occurs with anxiety, though the evidence for chronic anxiety disorders is still limited.

However, nitrous oxide is not generally used or approved as a long-term treatment for generalized anxiety disorder, panic disorder, or other chronic anxiety conditions. Its use is primarily restricted to short-term, situational anxiety management due to concerns about cognitive effects, potential for abuse, and lack of long-term efficacy data. In summary, scientific evidence supports its use for acute, situational anxiety, but not as a standard treatment for chronic anxiety disorders.