I was off Tobi for a couple of years, because of those symptoms. I have been able to start it back though, and as long as I do my Advair before it (ask your dr. first if you want to try it <img src="i/expressions/face-icon-small-wink.gif" border="0"> ), I can tolerate it. Taking magnesium and GSH seem to have helped too for me. I don't really have a problem with Colistin (am doing it now).