I don't know...all I know is I just don't want to have one more thing wrong with me so I want it to be from the MG! It certainly gets worse and feels better when I'm better MG wise. I smoked from 15-25 and used to get a lot of bronchitis up until I was in my 30's. I have Chronic Lyme disease, bartonella and babesia, rocky mountain spotted fever I am always fighting.