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 love 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.
Try a lower dose, I can usually get by with half the recommended dose. Worst case scenario, add Benadryl to the mix to knock you out. Being able to breathe is worth it!
What they said plus Mucinex (or the generic) makes the goo more fluid so it can drain out faster/better. Irrigation with a neti pot or sinus rinse bottle can be a huge help too. Use 2 packets of the salt that comes with the bottle; the extra salt helps draw water out of the tissue to reduce swelling. Try to snarf the water down the back of your nose and spit it out of your mouth.
Ask for the real Sudafed.
The little red ones say 4-6 hours, but one lasts me all day and minimizes side effects. They work quickly enough that you don't need to get ahead of your symptoms, you can wait until you feel you need more.
So it turns out that phenylephrine spray (i.e. topically applied) is actually super effective. It only lasts for a couple hours, although it's insanely fast to start working.
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