NAC is a supplement and as such very few formal studies have been done because there's no money behind them. I recall a study in Japan that found only a lot of it, 2400 mg per day, does any good. Most of us take 1200, two 600 capsules per day.

There are several uses for this supplement and no known side effects. At least, none that I've heard of.

For many of us, NAC thins our sputum making it easier to get it up and out. In my case, it works to thin my thick taffy like sputum to honey like.