I had a strange thing happen to me recently so I thought I'd pass along what I discovered.
I had such a problem with mucus in my nose and throat I could hardly breathe. I tried saline sprays, neti pots, nasal decongestants, etc but nothing helped.
I happened to do a web search for "too much mucus" and discovered the Soy Milk I'd been drinking causes excess mucus. I stopped drinking it immediately and within three days the mucus was reduced by at least 75%.
I also discovered some other culprits: coconut, dairy (of course), citrus (such as orange juice and lemonade).
Here are some new solutions that seem to work at reducing the mucus. I;ve tried them and they are helpful
Ginger ale (check the bottle to be sure it contains Ginger - some don't such as Schweppes)
Ginger root capsules
Pineapple juice and canned or fresh pineapple
Then there are the old remedies
Mucinex, N-Acetyl Cysteine (NAC)
Just my two cents. HOpe this helps someone