Nitrous oxide (N2O) briefly displaces oxygen in the brain for the duration of its effect — hence the typical dizziness and, in some cases, brief fainting episodes (syncope). Direct respiratory arrest is rare; fall injuries, on the other hand, are common.
Long-term use (large amounts daily or weekly) causes vitamin B12 deficiency with sometimes irreversible neurological damage:
- Numbness or tingling in the legs/hands
- Unsteady gait
- Difficulty concentrating, depressive episodes
Anyone who uses nitrous oxide regularly and notices such symptoms: get a medical check-up with a vitamin B12 level test and a neurological examination.
Acute suffocation from large amounts without an oxygen supply is possible but rare — usually only with use in enclosed spaces or with mask setups that block oxygen.
Practical risk reduction: small balloon amounts, sitting or lying down, with breaks to breathe normal air in between, not alone, not in water.