N-Acetyl L-Cysteine (NAC) is a modified version of the amino acid L-cysteine. The acetyl group makes it more stable and easier for the body to absorb. Once inside, it acts as a building block for glutathione, a critical antioxidant your cells produce.
People take NAC to thin mucus and support lung health. It aids the liver's natural detox pathways. Researchers have also looked at its effects on mood and repetitive behaviors.
A typical daily dose splits 600 to 1800 mg into two separate servings. Taking it with food often prevents stomach upset. NAC can react with certain medicines, so check for interactions.
Nausea, headache, and digestive issues are the most common side effects. NAC may strengthen the effect of blood thinners. Anyone with asthma should use caution. The safety of taking high doses for long periods is not fully known.