I went to an allergist for this issue last year. Turns out my post nasal drip was due to chronic sinusitis, a sinus infection that did not get properly treated/cleared up. He put me on antibiotics for 3 weeks, I only took a week of them because the yeast infection was ridiculous. Anyway, in the process, he also advised me to mix 2 tsp salt w/ 1 tsp baking soda, add to 8oz of warm water and with a steady flow spray the solution into my nose twice a day. If that water is too hot or salty, this can be painful. But untimately, you are inhaling salt water. You allow the solution to run right back out of your nasal cavity. I belive my solution bottle is from Sinumed, but it's kinda like a douche bottle (horrible comparison, but I had no other way of explaining.) When I actually remember to do this, I do not have post nasal drip. When I forget, I wake up with mucus pooled in my throat and end up vomitting to eliminate it.