Hello Jennifer. I sometimes go on inhaled tobramycin for 28 days when my lungs start to feel like they are getting infected. During the first two weeks on it; I feel like it is making things worse. I'd feel more congested, had wetter lungs and would cough more. By the end of the 28 days; it would all clear up and I would feel good as new again. My guess is that the 'toby' was loosening up mucous plugs, etc and getting deep down into my lungs, and is why I would get those initial side effects. I was on an every-other-month regimen on this drug for four yrs. Now, I do it as needed. Try to hang in there with your arikayce if you can. Sometimes things have to get worse before they get better.