Thrush is a fungal infection that occurs in your mouth. Typically, if you have thrush, you may have red sores. Sometime, thrush appears as white lesions in the mouth. By taking a probiotic, you can increase the presence of healthy bacteria in your mouth, especially when you take a higher dosage of probiotics like those in 60 Billion CFU probiotic. When you increase the healthy bacteria inside of your mouth, you have the ability to fight the fungus that causes thrush.