I am only on 250 mg Azithromycin every other day for the past 11 months. During that time I have had zero exacerbations and the way I understand it, the Azithro acts as an anti-inflamatory. I would not say I have decreased mucus. I would say that with the 3% sodium chl. I have easy mucus, easy to expel. I think somehow the azithro helps clear out the lungs of the stuff. I don't think it makes mucus but does somehow help along with the 3% to get it out of your lungs which is the whole point of not getting an infection. I think it does other stuff too like making a bad environment for bugs but not sure how that works. I have pseudomonas and that is why I take it. I will probably be going off it for a while soon as 1 yr is what has been studied as far as I know. I still have coughing...but I am walking up a steep hill now so...the cough is now just an annoyance. In any case I feel better in a way that is not connected to mucus quantity or frequency of cough....if that helps?