If the skin is only red, it does not necessarily belong to dermatitis, but may also be caused by capillary dilatation, spider nevus and other diseases. 1. Capillary dilatation: the cause of this disease is more complex, may be related to the influence of pregnancy, heredity and hormones and other factors, the patient’s skin will appear red spots, in the form of dots, patches and asterisks and so on. 2. Spider nevus: the cause of this disease may be related to the increase of estrogen, impaired liver function and other factors, the patient’s skin will appear in the shape of a spider nevus, radiating outward small blood vessel network. If the skin only appears to have red blood, generally may not be associated with dermatitis, it is recommended to go to a regular hospital, relevant examinations, to clarify the cause, and follow the doctor’s instructions for treatment.