G.B.
Using a humidifier can help keep allergens down inside. They do like a dry environment. I also find that all the allergy meds dry out my sinuses and throat because they are made to dry up runny mucus. If you are not having runny eyes and nose then you may be using the wrong meds.
I get dried out nose and I have minimal saliva after taking those pills. If I am having sinus pain I take real Sudafed. Just half a dose, then the snot and stuff become thinner and I have less trouble swallowing the thick super glue stuff trying to drain.
I find that sleeping slightly inclined helps too. I use a couple of pillows and am nearly sitting up sometimes. That really helps the drainage go down too.