N-acetylcysteine (NAC) is a compound that is derived from the amino acid L-cysteine. It has antioxidant properties and is commonly used as a dietary supplement and medication for various health conditions. NAC is known for its ability to increase levels of the antioxidant glutathione, which helps to protect cells from damage caused by oxidative stress. Research has shown that NAC may have potential benefits for a range of conditions, including respiratory disorders, psychiatric disorders, liver disease, and other health issues. Studies have also investigated the use of NAC in combination with other treatments for improving outcomes in individuals with certain medical conditions.