Dermatitis is a general term for acute and chronic non-infectious inflammatory diseases of the skin caused by various factors, and is clinically named according to the differences in causation, location, and duration of the disease. There are several reasons for the suspicion that dermatitis is contagious. First, for a long time in the past, due to the lack of health knowledge and lagging health education, folk have long believed that “skin diseases” are contagious, such as public bathrooms, swimming pools, etc. are prominently marked “no skin diseases allowed”, while In fact, only infectious skin diseases caused by bacteria, fungi, viruses and parasites are infectious and can be transmitted through direct and indirect contact. Infectious skin accounts for only a few of the more than 2,000 independently named skin diseases. On the other hand, non-infectious skin diseases such as dermatitis and eczema often have multiple endogenous triggers and show a tendency to symmetrical onset and generalized spread when stimulated by exogenous triggers, and are also often mistaken for being infectious.