Functional Vitamin B12 Deficiency Induced by Nitrous Oxide: Case Report of Acute Psychosis and Severe Neuropathy
BJPsych Open June 1, 2026 Rishabh Bajaj, Ajay Baskaran, Asma Javed
Chronic nitrous oxide use can cause functional vitamin B12 deficiency even when serum B12 levels appear normal, leading to severe psychiatric and neurological symptoms. A middle-aged man with no psychiatric history presented with confusion, paranoia, and aggression after using 6 to 10 nitrous oxide canisters daily for four months. Initial treatment with intramuscular hydroxocobalamin improved his mental state, but he self-discharged and returned days later with lower-limb weakness, numbness, impaired balance, and ataxic gait. Nerve conduction studies showed severe motor axonal neuropathy. The case illustrates that nitrous oxide oxidizes vitamin B12's cobalt ion, impairing myelin synthesis, and that clinicians should suspect this toxicity in patients with unexplained neuropsychiatric or hematological symptoms.