Bruising on both sides of the tongue may be caused by accidentally biting the mucous membrane, or the bite of the teeth may be abnormal. If you bite the mucous membrane accidentally while eating, bruises will appear, you can use mouthwash to rinse your mouth, and the bruises can disappear by themselves in about a month, so don’t worry about it. Black bruises on both sides of the tongue is common is the occlusal relationship between the maxillary and mandibular teeth is abnormal, most often seen in the deep overbite deep cover or anti-collision, teeth to be in the tongue for a long time to cause the tongue mucous membrane bleeding to form a black bruise, this situation can be used to gargle mouthwash, maintain oral hygiene, and orthodontic correction if necessary. Therefore, the tongue on both sides of the bruises are mostly seen in the above situation, you can go to the hospital stomatology department to see a doctor, follow the doctor’s instructions to deal with.