Red blood nevus is a very common clinical manifestation of dermatology. There are many reasons for the appearance of blood nevus on the body, and the most common ones in daily life are as follows: First, diseases of the internal system, especially liver system diseases, such as chronic hepatitis and cirrhosis of the liver, can lead to generalized scattered spider nevus, or red blood nevus. Secondly, children and pregnant women may have abnormal hormone secretion levels, such as abnormal secretion of androgens and estrogens, resulting in red blood nevi. Third, weight gain, for patients who are too obese, the fat in the human body contains a large amount of estrogen, and this hormone will form angiomas, thus appearing a large number of red blood nevi. Fourthly, medication, long-term use of contraceptive pills will lead to the increase of estrogen and the formation of hemangioma.