I suffer from extreme amounts of phlegm as well and doctors always diagnose it as Post Nasal Drip and prescribed Nasonex, Fluticasone, and more recently Azelastine. The Azelastine is performing better than the Nasonex and Fluticasone....but only for the nasal stuffed cavities and drip - the phlegm is quite another issue - sticky and feels like cellophane sheet across my throat that I cannot clear as it seems caught between my throat and my esophagus while hacking and coughing to try an clear it out.
-DinoD