It is not known if nitrous oxide causes drug dependency but its use can be habit-forming. Death can result if it is inhaled in such a way that not enough oxygen is breathed in. While the pure gas is not acutely toxic, it inactivates vitamin B12, with continued use causing neurological damage due to peripheral and central demyelination. Symptoms are similar to B12 deficiency: anemia due to reduced hemopoiesis, neuropathy, tinnitus, and numbness in extremities. While vitamin B12 supplementation is unlikely to prevent neurotoxicity, it is recommended as a first-line treatment when combined with abstinence. Pregnant women should not use nitrous oxide recreationally, because chronic use is also teratogenic and foetotoxic.
