Use Baking Soda
Here's another remedy that doesn't involve gargling: Mix 1 cup warm water, 1/2 teaspoon salt, and a 1/2 teaspoon of baking soda. Get a nasal syringe and squirt the mixture into your nostril, closing off the back of your palate and your throat. Tilt your head backward, forward, and to each side for eight to ten seconds in each position to get the solution through all four of your sinus cavities.
After you swish everything around, gently blow your nose. Try squirting in three or four bulbs full of the solution on each side of your nose. If you don't have a bulb syringe, you can snort the mixture out of your cupped hand. Try this process up to six times a day when you're dealing with postnasal drip. If you want to avoid future problems, do it twice a day [source: Shute].
Don't get crazy and add extra salt to this recipe. Too much salt will dry out your sinuses and potentially cause unpleasant side effects.