Colleen. I'm not sure how to answer as I've been on and off Tobramycin for almost 5 years. Some of the time has been rough. I've had different treatment periods--14 days on and 14 off or 28 days on and 28 days off.) When I'd go off of it and begin to get my strength and appetite back I would have to go back on it. I had to be taken off it completely early this year. Currently I'm doing OK but just waiting to get the report back regarding M Abscessus. Hope this is helpful.