Our radiation oncologist says the thick stuff/mucous is primarily from three sources:

1) sublingual saliva which is thick, sticky and ropy, comes to dominates salivary production (such as it is) when radiation shuts down the thin serous saliva from the parotid glands (the usual major source of mouth moisture)

2) mucous produced by damaged cells in throat.

3) phlegm from post-nasal secretions (also an effect of radiation)

He is a believer in guafenesin to help with (3) at least -- also using humidifier and sleeping with head somewhat elevated. Some patients are given suction machines as these can really help if the problem is severe.

As to the guafenesin, the point is to take the correct dosage of syrup -- it can be diluted to a considerable extent in water, just so the intake contains the appropriate dose. My husband did this so it did not burn, whereas "straight" from the bottle it was very irritating to his raw throat. We then discovered Mucinex and he was just able to get the tablet down, which (as Nelie said) cannot be broken or ground up as it's timed-release. It is good for 12 hours.

Our dental oncologist also said to use salt/soda rinses -- as many times a day as you can -- to heal the tissues.

It does get better, in fact, sometimes rather suddenly...

Gail