Cysteine, particularly in the form of N-acetylcysteine (NAC), has been investigated for its potential to support individuals with alcohol use disorder (AUD). The rationale behind its use is primarily based on its role as a precursor to glutathione, a major antioxidant, and its effects on glutamatergic neurotransmission in the brain. Animal studies and some small clinical trials have suggested that NAC may help reduce alcohol-seeking behavior and cravings by modulating the reward pathways and oxidative stress associated with alcohol consumption.

However, the clinical evidence in humans is limited and mixed. A few small-scale studies and pilot trials have reported modest effects of NAC in reducing craving and relapse risk, but results are not robust or consistent. Most clinical guidelines do not include cysteine or NAC as a standard treatment for alcoholism due to insufficient evidence. The bulk of support comes from preclinical research and theoretical mechanisms rather than large, well-controlled trials in humans.

In summary, while there is a scientific rationale and some preliminary data supporting the use of cysteine (NAC) for alcoholism, the evidence is currently weak (rated 2/5), and more rigorous studies are needed before it can be recommended as a standard therapy.