The first thing to do is to determine the cause of the blackness on both sides of the tongue, such as drugs and food, gastrointestinal disorders, etc., and then make a solution according to the cause. The darkening of the tongue can be caused by the consumption of certain foods or medications, such as candies with melanin, black sesame seeds, etc. The blackening of the tongue can also be caused by the consumption of iron, antibiotics, and so on. This can be resolved by stopping the consumption of these foods or medications. Gastrointestinal dysfunction can also lead to black tongue, such as indigestion, constipation, diarrhea, etc., after gastrointestinal dysfunction salivary PH value will be reduced, so that the tongue cell adhesion to enhance the filamentous papillae keratin lengthening, if infected with microorganisms, will lead to black tongue, this time can be solved by adjusting the gastrointestinal function.