WEDNESDAY, Dec. 10, 2025 (HealthDay News) -- Nitrous oxide (N2O) can offer fast-acting depressive symptom relief, according to a review published online Nov. 30 in eBioMedicine.Kiranpreet Gill, from the University of Birmingham in the United Kingdom, and colleagues conducted a systematic literature review to identify data on the efficacy and safety of N2O in depressive disorders.Based on seven included clinical trials (247 participants), the researchers report that N2O was administered via inhalation at 25 percent or 50 percent, as single or repeated sessions, with comparators including air, oxygen, or midazolam. For the three trials administering 50 percent N2O in a single session, there were significant reductions in depressive symptoms at two hours and 24 hours. However, the effect was not significant at one week postinhalation. There were reports of mild and transient adverse events, with 25 percent N2O generally better tolerated. Most trials were early-phase and focused on short-term outcomes in adults with major depressive disorder or treatment-resistant depression."Our analyses show that N2O could form part of a new generation of rapid-acting treatments for depression," Gill said in a statement. "Importantly, it provides a foundation for future trials to investigate repeated and carefully managed dosing strategies that can further determine how best to use this treatment in clinical practice for patients who don’t respond to conventional interventions."Several authors disclosed financial ties to the pharmaceutical industry.Abstract/Full Text.Sign up for our weekly HealthDay newsletter