Bitter tongue may be the cause of bile reflux, bile said to be bitter bile, bile reflux into the mouth, may cause the symptoms of bitter tongue. However, other problems should also be ruled out. If combined with a smelly mouth, you need to consider whether you use periodontitis, coronitis, and bad habits such as smoking. If combined with a dry tongue, consider whether there is snoring in sleep. If combined with a dry and numb tongue, consider whether there is insufficient blood circulation, high blood viscosity or insufficient blood supply to the brain. Therefore, there are many causes of bitter tongue, and further diagnosis is needed in combination with other related symptoms or tests.