What do you do for a sinus drip?

Use a netipot daily: Fill 1/2 way with warm water. Add a few pinches sea salt, dissolve. Then over the bathroom sink, put spout of Neti Pot flush with one nostril and tip it up so salt solution runs down into your upended nostril and hopefully comes out the opposite nostril. Repeat # of times.

Depends on the cause: Multiple issues can cause a nasal drip from a simple cold to allergies and even other issues such as reflux. Treatment should be based on a full history and exam by a medical professional. There are many excellent treatments, but the cause should be determined first.