There's both phlegm (from the severe throat irritation and chest congestion) and thick mucosal saliva from the sublingual glands. The latter tends to increase during radiation, at least proportionately (as the thin watery saliva from the large parotid glands is reduced or even eliminated by the radiation). This is the ropy sticky stuff that clogs the mouth. Salt and soda rinses (or soda water) really help and should be repeated often as they also help with mouth sores. the phlegm can be helped by use of guafenesin -- either as the syrup (dilute with water as it may burn if full-strength) just make sure to take full dose -- or with the timed-release tablet Mucinex, but the latter is a large pill and difficult to get down when you have a sore mouth and throat!

My husband Barry was also helped by use of a humidifer at night, which is the worse time.

Severe phlegm can also be a symptom of a low-grade infection -- Barry had a sudden massive increase in clogging phlegm one day, going through a box of tissues every few hours, along with a low-grade fever and general malaise. He had to go in for a traetment that day and his doctors got on it immediately, blood tests, chest xrays etc. and they found he had a penicillin-resistant staph blood infection, very dangerous if they had not caught it when they did. He was admitted to the hospital and 24 hours on the vancomycin IV and the excess phlegm stopped! I should note that this sputum was "colored" -- that is, it had a trace of pus like when you are recovering from a bad chest cold.

Barry had a similar set of symtroms a few weeks later which they first worried was a recurrence of the bacterial infection but which turned out to be a low-grade pneumonia. Again, a couple of days' antibiotics and the excess phlegm went away. However the pneumonia took 2-3 months to completely resolve (per chest xays).

So any sudden increase in phlegm, especially if it appears tinged with pus or blood, and most especially if there is any fever -- call the doctor. Also, low-grade pneumonia can linger for months, and be essentially symptomless, and I think this is the cause of some folks' persistent phlegm and congestion, when otherwise they are starting to heal well from treatment.

Gail