I have dry, yucky mouth, and dry lips. I went to the doctor and they diagnosed it as thrush. I was given nystatin, and I took it for two weeks. It did seem to help, although it didn't solve the problem. I was back in the doc's office on Thursday, and she seemed to think all my thrush symptoms were gone. I had some blood drawn as part of a routine physical, and was going to check for other possible causes, like a B 12 deficiency. In the meantime, she told me that I didn't need to take the nystatin anymore. And now, a few day later, my serious dry mouth is back. I haven't gotten the blood test results back yet, but I thought I would get your feedback. Why might I have dry mouth symptoms that have gone on for weeks, despite a nystatin regime?