There are a number of things that can cause a whitish coating or white spots to develop on the tongue, including the following: Leukoplakia. This condition causes cells in the mouth to grow excessively. That, in turn, leads to the formation of white patches inside the mouth, including on the tongue. Although not dangerous on its own, leukoplakia can be a precursor to cancer. So it is important for your dentist to determine the cause of the white patches on your tongue.