Nitrous oxide (N2O; laughing gas) is clinically used as a safe anesthetic (dentistry, ambulance, childbirth) and appreciated
for its anti-anxiety effect. Since five years, recreational use of N2O is rapidly increasing especially in the dance and festival
scene. In the UK, N2O is the second most popular recreational drug after cannabis. In most countries, nitrous oxide is a legal
drug that is widely available and cheap. Last month prevalence of use among clubbers and ravers ranges between 40 and almost
80 percent. Following one inhalation, mostly from a balloon, a euphoric, pleasant, joyful, empathogenic and sometimes hallucinogenic
effect is rapidly induced (within 10 s) and disappears within some minutes. Recreational N2O use is generally moderate with
most users taking less than 10 balloons of N2O per episode and about 80% of the users having less than 10 episodes per year.
Side effects of N2O include transient dizziness, dissociation, disorientation, loss of balance, impaired memory and cognition,
and weakness in the legs. When intoxicated accidents like tripping and falling may occur. Some fatal accidents have been reported
due to due to asphyxia (hypoxia). Heavy or sustained use of N2O inactivates vitamin B12, resulting in a functional vitamin
B12 deficiency and initially causing numbness in fingers, which may further progress to peripheral neuropathy and megaloblastic
anemia. N2O use does not seem to result in dependence. Considering the generally modest use of N2O and its relative safety,
it is not necessary to take legal measures. However, (potential) users should be informed about the risk of vitamin B12-deficiency
related neurological and hematological effects associated with heavy use.