My mouth is constantly really dry, like I don't produce enough saliva. This makes my tongue kind of rough. I hate making out with my boyfriend because of this, and drinking water beforehand does NOT help. Chewing gum or sucking mints doesn't help at all either. I don't think its because I'm dehydrated.
The site has a few questions at the bottom of the page to determine if you have dry mouth, which can be caused by a number of things. Even if you don't think you are dehydrated, you might actually be. Try drinking more water everyday and see if that helps.
The site mentions that people who are very anxious tend to get dry mouth, so that might be an issue. I actually remember temporarily having the same feeling when I was really nervous speaking in front of the class a few years back. I had the same feeling several years ago when I was with a guy I really liked. So try to think about anything (or more than one thing) that might be causing you to feel overly stressed, anxious, and/or depressed, and try addressing that issue(s).
In the meantime, consider using Biotene, a mouthwash for dry mouth:
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