How long does post nasal drip last?

yesterday I found out i have post nasal drip. The thing is I don’t have any allergies. I was wondering if it was viral. How long does it last? what are some tips to make my throat better?

I had it when I was younger. It usually only last a night or two. It can be caused by having a cold or allergies (you might have one you don’t know.). I know it’s a pain and makes it hard to sleep. Try sleeping on your side if you can. That helps.