Rhinitis causes post nasal drip. Rhinitis is an inflammation of the inner lining of the nose. Allergies such as pollen, dust, animal dander, chemicals, and many other things can cause rhinitis. Even food allerges can be the problem. There are many things in the air unknown to us that may be the cause.

I personally have found that irriating the nasal passages with salt/soda solution will help rinse out allergens and reduce post nasal drip. I use 1/2 teaspoon plain salt, 1/2 teaspoon baking soda in 1 cup boiling water. Stir to dissolve, strain thru paper coffee filter. COMPLETELY COOL. Put solution in clean nasal spray bottles. To use, hang head off bed (lie on back) put a few squirts salt solution in each nostril. Turn head slowly side to side, massage cheeks. Say KKKKKKK while getting up to keep solution from running down throat. Blow nose gently as needed. I sometimes add 1 or 2 drops plain glycrin to each bottle of salt solution to prevent drying out nasal passages too much. Salt and baking soda are both drying. My doctors have approved using the above. I am not a medical professional.