Oral thrush is a fungal infection of the mouth. It is not contagious and is usually successfully treated with antifungal medication. It is also called oral candidosis (or candiasis) because it is caused by a group of yeasts called Candida. Symptoms of oral thrush can include: white patches (plaques) in the mouth that can often be wiped off, leaving behind red areas that may bleed slightly loss of taste or an unpleasant taste in the mouth redness inside the mouth and throat cracks at the corners of the mouth a painful, burning sensation in the mouth In some cases, the symptoms of oral thrush can make eating and drinking difficult.