CMAJ | August 21, 2023 | Volume 195 | Issue 32 E1075 Nitrous oxide (N2O) has become a popular but dangerous recreational drug. Colloquially referred to as “laughing gas,” it was first used therapeutically in 1844 for patients undergoing dental surgery.1 Although a weak anesthetic, it remains in use today, especially for pediatric and dental procedures.2 Its recreational use is now recognized as...