How can i stop drooling?!

You most likely are not breathing through your nose while asleep. Try getting an anti-histamine from the pharmacy. Speak to the pharmacist about which would be most effective. Don't worry, you don't need a prescription, you just need to show a state ID to get them because they are controlled now and sold behind the pharmacy counter.

If the problem continues, speak to a doctor. Could have other issues such as deviated septum.

Personal Experience

Your mouth probably stays open during the night. I'm not sure you can really prevent your mouth from opening unless you tape it shut. For me, I try to sleep in a position where my mouth won't open, usually on my side, and I try to keep my mouth closed right before I drift off to sleep.