Nitrous oxide (nitrogen gas) can provide rapid and short-term relief from severe depression, especially in patients who have not responded to conventional antidepressants. A meta-analysis showed a significant improvement in symptoms as early as 24 hours after a single inhalation of nitrous oxide for 60 minutes, with repeated treatment providing a more lasting effect. In younger patients, improvement was noted in approximately 85% of those treated. Side effects were mostly mild and transient, with patients reporting fewer side effects at lower doses of nitrous oxide compared to placebo. The research highlights the need for further larger and long-term studies to confirm the safety and effectiveness of this treatment. Administration of nitrous oxide should take place under the supervision of a psychiatrist to avoid inappropriate use and ensure the correct indication. This therapy represents a promising alternative for patients with resistant depression for whom conventional treatment methods have failed.