Pseudoephedrine

That exact med. Not the Sudafed with the useless phenylalanine nonsense that has been demonstrated to do fuck all. You may have to ask the pharmacist for it - it's not prescription but Feds made stores move it behind the counter. Ask for the generic, it's cheaper. Really works

Side effects suck though, dry mouth, maybe a little agitation. But it'll clear you right up.

Get allergy tests. Mine was allergies to pet hair, dust etc. I got a permanent fix unintentionally. Had throat cancer, the chemo and radiation damage drops the mucous creation to about 50%, so post nasal stopped being a problem. LOL

Go to an ENT and determine what the problem is.

Sinus rinse and flonase (the light mist one) work best for me.

theres a trick involving pulling on your ear and hard stroking your cheekbone.

theres another trick where you pull out nosehairs.

theres another where you eat spicy food.

some people use a neti pot.

Loratadine every day, for a year.

Phenylephrine AS Ephrine Nose Drops.

It's ineffective orally, but it sure as heck works up your nose. Just occasionally though, you can get dependent, making things worse in the long run.

My dad used antihistamines

Flonase worked really well for me, bit it can be very drying for some people

Perhap remove the irritant? Maybe it's the air quality, bedding, or fabric softener?

A lot of water, dusting, washing your bed sheets, exercise, and watching your diet, all help a bit.

I like to take a hot shower, cup the hot water, and blow my nose into my hands until it stops being congested.

I also uh...picked my nose clean during this time, but I don't recommend this.