This is the product.
Okay, its used for ocd as well. I had a bad habit of staying in bed after I woke up. Just lazing away. I didnt like this but I was not motivated. I could stay in bed all day if I knew I could have gotten by with it. Saying this this was a behavior that was hard to change. However the morning after the very first day I took NAC I got up and made my bed which never happens. That was actually shocking to know its helped me in this manner. I havent lazed in bed since May 20. I thought it was March. I looked back in my phone calendar to make sure. Then I begin to notice more energy. Quicker thinking. Memory and my mood and disposition got better. I was happier and stopped worrying about a few personal stuff I didnt need to worry about. Then after months of being on it my asthma went away. It almost left with vitamin d3 at,10,000iu a day. But the nac did it for me. It also has helped with my blood glucose. I dont have the spikes like I used to. And I am so sensitive to carbs and dont eat breads or grains but will eat a potatoe or fruit at times it would spike. Anyway, I feel its helped me in more ways than any supplement ever had. And inflammation. I its helped inflammation in my knees. I now have incorporated jogging exercises in the evening for 20 minutes. Its converts to glutathione which is the master antioxidant that fights colds, flues infections, illnesses in general.
It also helps detox the liver. It is used in emergency rooms for tylenol toxcity. There are a lot out there. Many many people reported it helping with recovering from the C2 virux. Supposedly this is a reason many articles claim why the fda is banning the otc privileges.
Just my experience and what I feel it had done for me. With everything else you want to take asking your doctor wouldnt hurt.
In short to answer your question how long, immediately and then started experiencing more benefits I mentioned. Everyone is different so dont expect it to help ypu the same way. Also, find out if it interacts with any other medication you are taking. Always find out my googling or asking doctor or, pharmacist.