Spider nevus is not a precursor of disease, and its formation is caused by elevated levels of estrogen, which can be seen in adolescent and pregnant women and in patients with hepatitis and cirrhosis of the liver. Spider nevus is formed due to the increase of estrogen level and decrease of androgen level in the body, which dilates the terminal branches of small arteries in the skin. Adolescent women and pregnant women who produce too much estrogen can develop spider nevi, which do not require special treatment and can disappear gradually. Spider nevus can also appear in some disease patients. For example, in patients with hepatitis and cirrhosis, spider nevus may appear due to impaired liver function and reduced inactivation of estrogen. If the spider nevus is accompanied by jaundice, nausea and vomiting, abdominal pain, fatigue and other symptoms, you need to be alert to the possibility of hepatitis, cirrhosis and other diseases, and should be diagnosed by a doctor and treated as soon as possible. When spider nevus appears, you should consult a doctor in time and choose the appropriate treatment method after examination and diagnosis by a doctor, so as to avoid delaying the condition.