Black spots on the lips should not be ignored because the health of the skin reflects the health of the body. The main causes of black spots on the lips are allergies, exposure to drugs, vitamin deficiency, excess of trace elements, and some hereditary diseases. Allergic reactions will occur when the lips come into contact with some allergens. When the lips are allergic to cosmetics, food flavors and some drinks, black spots will appear on the lips. These substances contain irritants that come in contact with the lips and eventually lead to lip allergy. The side effects of drugs can also cause black spots on the lips, such as some drugs for the treatment of mental illness will cause black spots on the lips, these black spots will disappear after stopping the drug, lack of vitamins will lead to black spots on the lips, the most important vitamin is vitamin B12, lack of these vitamins, black spots on the lips will appear. This is the time when people can take proper vitamin supplements. Excess of trace elements iron will also lead to black spots on the lips, when the body gets too much trace elements from the food it eats it will put these substances in the organs. Therefore, it is important to pay attention to the amount of micronutrients taken in life. Dark spots on the lips may also be caused by some family genetic diseases, and colon – lip dark spot syndrome is a typical example of such a disease, which is a genetic disease. Abnormal melanin deposition in the colon, growth of multiple polyps and dark spots on the lips are the main symptoms of this disease, which is highly susceptible to colon cancer and needs to be taken seriously. The cause of black spots on lips is mainly due to allergies, so try to avoid contact with some allergy-prone substances in daily life. Avoid contact with allergic substances in daily life, and seek medical attention promptly after the appearance of dark spots.