The bad news: Excessive use (e.g a case of 24 whippets every day for weeks on end) causes nerve damage. The good news: it's at least somewhat reversible, and you can control it not only be easing up on the nitrous, but by taking vitamin B-12 supplements (sublingual is absorbed best). link: http://www.ajnr.org/cgi/content/abstract/19/5/894 Myelopathy caused by nitrous oxide toxicity PJ Pema, HA Horak and RH Wyatt Department of Radiology, Ohio State University Medical Center, Columbus, USA. We describe a case of myeloneuropathy resulting from nitrous oxide abuse. MR imaging of the spine revealed symmetric abnormal signal in the posterior columns of the cervical cord. Myeloneuropathy is caused by inactivation of vitamin B12 by nitrous oxide. This syndrome can also be seen in patients with borderline vitamin B12 deficiency who have recently been anesthetized with nitrous oxide.