My 4 almost 5 year old has been on Pulmozyme since 2 years old even without any lung involvment at the time.
She has had a bad cough the past while and now the docs say possibly an asthma component. She is now on pulmozyme twice a day and albuterol 3 times a day. along with abx and increased treatments and Prednisone. Hopefully something helps! She has never had a cough til now either. She does culture Staph for the past 9 months though.
My 8 month olf has been on Hypertonic saline 7% mixed with Sodium Chloride .9% (I guess it make a 3%). She has been on that since about 2 months old. She has also been on Pulmozyme that whole time. Also albuterol.
I am sure she can get back to no cough. Don't stress too much. It will just take time.
Take care.