I have been taking 600 mg of NAC 3x a day for years . There have been some small studies showing that it is helpful in thinning mucus. I recently came across a nbi article reviewing 8 small studies looking at whether NAC works to dissolve biofilm in the lungs. Yowza! I had never heard that before. I have been looking for the article and if I find it I will post it. I get the NOW brand of MAC from Amazon.