We had been on TOBI for many years, on the 28 days on, 28 days off cycle. My daughter always felt better when she did the TOBI. She is off now as she is doing the Cayston 28 on, 28 off. The only side affect she had on TOBI was that her voice got really raspy, sounded kind of like an old women that had been a 2 pack a day smoker-we told her it made her sound sexy-she found that funny. We don't worry too much when the doc puts her on new meds, we just do it as prescribed. One thing that has made her stronger and her lungs stay healthy is exercise. She is a runner and her doc loves it. I wouldn't worry too much about how long Maggie needs to be on TOBI. all the meds and treatments are just a way of life. We are getting ready to send our daughter off into the college world in the fall-and that is way scarier than the CF.