A sudden black and purple vesicle in the mouth is usually caused by submucosal bruising due to traumatic factors, such as burns and bites, and is usually not a cause for concern at this time. Such cases can also be caused by the sudden appearance of oral mucosal pigmented nevi, which protrude from the surface and appear as black and purple vesicles. However, because of the sudden onset of the disease, the case of hemangioma can usually be excluded, and its occurrence requires a certain process. Common causes and treatment methods 1. Blood bubble: If the black purple bubble is caused by trauma, it can usually heal by itself. In case of breakage, it is necessary to apply iodophor and disinfect locally to prevent infection. At the same time, spicy, cold and hot food should be avoided to avoid stimulating the wound and causing pain so as not to delay wound healing. 2. Oral mucosal pigmented nevus: Since there is no obvious projection, it is mostly found by chance and patients think it is a sudden appearance of a black violet bubble, most of them are benign cases, but patients should not ignore them. Because this disease has a certain risk of malignant transformation, it needs to be clearly diagnosed by a doctor as early as possible and in time. If the disease does not cause adverse reactions, such as no pain, ulcers, etc., usually do not treat yourself. If there is pain, hardening and other manifestations, suggesting the possibility of malignant change, further examination is needed to clarify whether medication or surgery is needed under the doctor’s examination. Attention In daily life, patients should avoid eating foods that are too hot or too hard, and do not eat too fast to avoid damaging the oral mucosa and causing black purple bubbles. If the possible factors of producing black purple vesicles are not clear, or if you cannot determine whether it is a blood vesicle or a pigmented nevus, you can consult a doctor for a clear diagnosis. Usually the diagnosis can be clarified under professional examination and the appropriate treatment can be given.