If you can clear up the sinus or allergy issue causing the post-nasal drainage, that would help. Also, stay away from dairy products before you sing. Drinking tea or lemon and hot water are accepted methods for clearing the throat before singing.

I don't know if this will work for you. I had a bad sore, dry throat. I drank sweet pickle juice and it was gone in less than 2 minutes.

don't drink anything cold before singing as it will constrict the throat muscles. if your throat is dry you are singing too much, too loudly, and straining too much when you hit any upper middle or high range notes. it happens to me when I go anywhere near upper middle range. I used to sing chorus then stopped for years and recently picked it back up some time ago. I've noticed the changes in how well I sing asnd have narrowed it down. hope this helps.

I have the same problems mostly because of smoking and sinus/allergy problems. there's a few things you can do, most times when you have drainage like that it is a sinus infection or allergy that has gone on for some time. Go to the doc, they ca usually get you on something like Clarinex, Cortinex or Singular which can clear the sinuses up. I saw my GP because I was having this problem when performing and having to clear my throat, etc all the time or when I would hit a high note mucus would cause me to get a raspy noise during higher registers. With that solved I was doing sooo much better. Aside from that I also have a routine, obviously not one you are going to do on an impromptu performance but if performing semi-professionally or more you might want to do some of this. Warm up, it's true just like athletes need to warm up the muscles singers need to warm up their throats, doing some simple scales or voice exercises can help warm up the throat and allow for more range and less chance of damage to the vocal chirds. Don't drink cold drinks. Some will say drink hot tea with honey. BUT if you have the mucus issue honey will sometimes make your throat even more coted and icky. I know it sounds weird but one of the best things to take is a shot of vodka. Don't chug the entire bottle, everyone knows alcohol dehydrates you and you need hydration for good singing, but sipping, gargling some 100% vodka can relax the throat and help line and protect it as well. I've tried cough drops, teas and sprays and some of them left me with cotton mouth, some made my thirsty, some didn't do anything but warming up, drinking something warm and then before performing just sipping some vodka does the trick..strange but true!