@beatrixflower Hi Darla, I started with 7% because I hope to kill (or at least limit growth of) the MAC found in my lungs (See also tables 2 and 3 of the paper Sue referenced in the other thread). I've never had problems with 7%. The first time I used it, it caused me to sneeze and cough in the middle of the nebulizing, but that was the worst effect and only happened a few times. I talked my PCP when I was in Tucson into prescribing it for me after showing her the article at my annual physical. My ID doctor now prescribes it. (I'm in MIchigan now.)