Oxygen + nitrous oxide

Oxygen + nitrous oxide is a fixed-ratio combination medical gas, typically containing 50% nitrous oxide and 50% oxygen. It is administered via inhalation for its analgesic (pain-relieving) and anxiolytic (anxiety-reducing) effects. The mixture acts rapidly—onset within about 30 seconds—and the effects last for approximately one minute after cessation. Nitrous oxide functions primarily as an N-methyl-D-aspartate (NMDA) receptor antagonist in the central nervous system, producing dissociative anesthesia and analgesia while maintaining consciousness at sub-anesthetic doses. Oxygen ensures adequate tissue oxygenation during administration of nitrous oxide, which can otherwise displace atmospheric oxygen in the lungs. This combination is widely used for short-term pain relief during procedures such as childbirth, dental work, trauma care, and minor surgical interventions[5]. It is also used in emergency medicine settings due to its rapid onset and offset of action[5]. The product is supplied under various brand names such as Entonox or Nitronox[5].

Brand names

EntonoxNitronox

Other names

laughing gas and oxygen50% nitrous oxide/50% oxygen mixture