NAC is used as a supplement by people seeking to benefit primarily from its mucolytic mechanism of action, or its role as a glutathione precursor to improve their general health. 

NAC is also used as an antidote to acetominophen (paracetamol) toxicity. 

One of the ways in which paracetamol may cause liver damage (as well as alcohol) is by decreasing glutathione levels. 

A deficiency in glutathione levels induces a weakened immune system and contributes to oxidative stress, where the athletic population is a group especially exposed to this.