Hi Sally,

I have had my sputum samples rejected as well and it's frustrating when you feel like you're trying everything to get a good sample. In addition to what you're already doing
taking the Mucinex beforehand might help to thin things out if you know you have to provide a sample the following day and like others have mentioned trying first thing in the morning.

Have you been going to the physician's office/lab for sputum induction or trying at home? Sometimes it's easier to take the cups home and then bring them the day of the appointment because it's more relaxed and you can really get into the different positions and really try everything.

When you're in your postural drainage position, you can also dry percussion using a cupped hand over the affected area.

Here is helpful information about positions and percussion: https://hopkinscf.org/wp-content/uploads/2019/06/postural_drainage.pdf

My right middle and right upper lobes are affected so after I nebulize, I lie flat and use my hand to percuss above my right breast and then lie on my side and percuss under my breast area and side. If I'm not coughing by this point, I'll do Autogenic breathing + Aerobika and try to wait to huff cough until after I've done all that.

Hope this is helpful!
Kate