I'm still coughing from allergies and it has been over a month. Drives me nuts and I think I cracked a rib at the same time. Hurts like crazy too.
My Dr. suggested gargling at least twice a day with listerine. I don't know how but it does stop some of the coughing, especially at night. I sleep with my head a bit elevated and have stopped taking cough meds at night.
I also use a nasal rinse. Our allergies are crazy, we are on a large wooded lot with cedar elms and we are allergic to them... they are pretty though...
Mine is allergy related and I had been taking Claritin daily. I was told to switch up allergy meds because you get immune to the same one.
Also, local bee pollen or local honey helps with the allergies around here.
Good luck!