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Well, since the post nasal drip
persists in your case you must think in lines of allergy. What is important is you must find out what is causing this allergy. Common allergens are pollen, mold, dust, pet dander, cosmetics or drugs. You must get an allergy test done, either a skin test or by RAST, to know what you are allergic to. Seasonal allergies are generally due to pollen or dust.