The Short Version
NAC has not been proven as a cure or effective treatment for OCD, bipolar disorder, or schizophrenia. Every high-authority peer-reviewed source describes NAC exclusively as an investigational adjunctive therapy with preliminary, mixed, or inconclusive results. No major regulatory authority — including the FDA, EMA, or WHO — has approved NAC for any of these three conditions. The largest NAC-OCD trial was still enrolling participants as of 2025, and researchers consistently call for additional large-scale trials before efficacy can be established.