Benzonotate for coughing

I have bronchiectasis and I know I'm not supposed to take cough suppressants, but when I get a cold or some minor respiratory issue, I cough 24/7. My throat hurts, my ears, my whole body, and I can't get out of bed. And I'm exhausted. My PCP gave me benzonotate and I took one at 2:00pm. My cough didn't go away for another 4 hours, but once it did I got through the whole night and most of the next day without coughing. How does taking a cough suppressant harm our lungs or interfere with airway clearance? When I have days or weeks when I'm coughing 24/7, I really need some relief.