Thickening and bluing of blood vessels under the tongue may be a normal phenomenon and does not need treatment, or it may be caused by sublingual hemangioma, sublingual varicose veins and other factors, if the condition is serious, it needs to be treated. 1. Normal phenomenon: there are more blood vessels under the tongue, which are closer to the tongue mucosa, and some patients with rich blood flow in the tongue will have obvious exposure of the blood vessels under the tongue, which looks thick and blue, which is a normal phenomenon and doesn’t need treatment. 2. Sublingual hemangioma: it will cause purple or blue blood vessels under the tongue, and sometimes there will be lumps. If the hemangioma is relatively small, regular review will be fine. If it is a serious lesion or the hemangioma is large, this situation requires early intervention and active treatment. 3. Sublingual varicose veins: High pressure on the sublingual veins and poor blood return can cause bruising of the sublingual blood vessels, in this case, no special treatment is usually needed. If the patient has bleeding, pain and other symptoms, then active treatment is needed. If the patient has symptoms of thick and blue blood vessels under the tongue, it is recommended that the patient consult a doctor in time to clarify the degree of development of the disease and treat it in time to avoid aggravation of the condition.