White tongue may be caused by Candida infection, oral leukoplakia, leukokeratosis, and poor hygiene. 1. Candida infection: it is a fungal infection, usually white velvety patches appear on the tongue, which is a kind of pseudomembrane and can be wiped off by exertion. 2. Oral leukoplakia: manifested as white or gray patches on the tongue, making the tongue slightly rough and astringent, commonly found in smokers. 3. Leukokeratosis: manifested as white patches or patches with unclear boundaries on the tongue, usually due to long-term mechanical or chemical stimulation, such as betel nut chewing habits. 4. Poor hygiene: tongue is generally associated with poor oral hygiene, there are white hairy tongue makes the tongue look white. When the symptoms of white tongue appear, you should go to the hospital in time for examination and treatment under the guidance of the doctor.