N-Acetyl-L-Cysteine (NAC) is one of the most effective and versatile supplements on the market today. Clinicians in functional and integrative medicine, in addition to those treating mental health disorders, often use NAC as one of their primary supportive tools for their patients. NAC is a powerful antioxidant well known for its potent ability for detoxification, respiratory function, and cellular health. In the brain NAC can support clearance of over stimulating neurotransmitters that lead to irritability, anxiety, and obsessional thinking.