Tongue old anti-sweet water, may be due to the consumption of sweet food, but also may be oral diseases, digestive diseases and other reasons. 1. Due to eating sweets: taking foods or drinks with high sugar content can lead to residual sugar, causing the feeling of sweet and sour water on the tongue. 2. Oral diseases: for example, inflammation of the tongue, gingivitis, abnormal secretion of salivary glands, may also lead to the tongue old anti-sweet water. 3. Digestive diseases: for example, gastrointestinal inflammation and indigestion may cause abnormal secretion of digestive juices, and the reflux of digestive juices into the oral cavity may also cause a feeling of sweet water on the tongue. There may be other reasons why your tongue is always refluxing sweet water, so you need to go to the hospital in time for further examination and treatment as prescribed by the doctor.