What is nitrous oxide (N2O), also known as laughing gas?

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Last updated: April 3, 2025 • View editorial policy

From the Guidelines

Laughing gas, also known as nitrous oxide, is a colorless gas used as an anesthetic and analgesic in medical settings, particularly for its rapid onset of action and lack of serious side effects, as noted in the BTS guideline for oxygen use in adults in healthcare and emergency settings 1. The use of nitrous oxide/oxygen mixtures, such as Entonox, has been widely accepted for many years, especially in providing analgesia during childbirth and in trauma patients. Key benefits of Entonox include:

  • Rapid onset of action, occurring within a few breaths
  • Lack of serious side effects, with the main side effect being drowsiness
  • Rapid washout, allowing patients to regain consciousness quickly
  • Self-administration using a facemask with a demand valve, which opens to allow gas to flow when it detects an inspiration However, it's crucial to consider the potential risks and contraindications, such as:
  • Contraindication in patients with known emphysema due to the mixture's potential to expand in air-filled cavities
  • Concerns about precipitating hypercapnia in patients at risk of hypercapnic respiratory failure
  • Risk of swinging from hyperoxaemia to hypoxaemia if the patient has a cause for hypoxaemia and releases the mask As stated in the guideline, Entonox is best avoided in patients who are at risk of hypercapnia or hypoxaemia 1.

From the FDA Drug Label

NITROUS OXIDE USP UN1070 Rx only. Nitrous Oxide The answer is: Nitrous Oxide is also known as laughing gas. 2

From the Research

Definition and Properties of Laughing Gas

  • Laughing gas, also known as nitrous oxide (N2O), is a small and simple inorganic chemical molecule with analgesic and anxiolytic properties 3.
  • It has been used for over 150 years in clinical dentistry for its analgesic and anxiolytic effects 3.

Medical Uses of Laughing Gas

  • Nitrous oxide is used worldwide for analgesia and anesthesia 4.
  • It is also used to treat neuropathic pain, and its effects can be enhanced when combined with oral opioids 5.

Recreational Use and Risks of Laughing Gas

  • Nitrous oxide is used for recreational purposes by some people, which can lead to major side effects such as myeloneuropathy, delusions, and emphysema when used in excess 4, 6.
  • The misuse of nitrous oxide can cause acute and chronic complications, including hypoxia, barotrauma, burns, and neuropsychiatric disorders 6.

Environmental Impact of Laughing Gas

  • Nitrous oxide is a potent greenhouse gas, approximately 300 times more damaging than carbon dioxide, with a longer lifetime in the atmosphere 7.
  • There is a need for further exploration and development of low-cost gas-sensing technologies to monitor and mitigate nitrous oxide emissions 7.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.