Thrush is the result of an overgrowth of a yeast fungus called Candida, referred to as candidiasis. It's the same one that causes vaginal yeast infections. When you get it in your mouth it's an indication that there's an imbalance between good fungus and bad fungus in your gut. You can never fully get rid of Candida, but it's normally held in check by your good gut bacteria. So if you have thrush you can treat it with meds, probably an antifungal like Nystatin, but you really should find out why it's there in the first place. The meds will reduce it, but it will come right back when you stop the meds if you don't find and fix the underlying problem. It's also contagious, so don't be french kissing guys anytime soon.