Shi Weimin, the chief physician of dermatology, is a special expert who went to the University of Melbourne, Australia to study AIDS vaccine. He is currently the director of dermatology and venereology and the director of teaching and research section. Member of Dermatology Branch of Chinese Medical Doctor Association, Dermatology Branch of Shanghai Medical Association and Dermatology Branch of Shanghai Society of Integrated Traditional Chinese and Western Medicine. Really understand allergic dermatitis q: the definition of allergic dermatitis? A: Skin diseases are generally divided into two symptoms: inflammation and tumor. And 80% of skin patients are inflammatory symptoms. Therefore, dermatology has no specific definition of allergic dermatitis. From a medical point of view, contact dermatitis, urticaria, drug eruption and eczema are generally classified as allergic dermatitis. Expert analysis: Considering the understanding of the general public, in a broad sense, inflammation caused entirely by allergies is called allergic dermatitis. Q: What is the pathogenesis of allergic dermatitis? A: When a specific individual comes into contact with an allergen for the first time, it will produce corresponding antibodies, which are fixed in the skin and mucosa. When the same allergen is encountered again, it will lead to degranulation of mast cells and basophils, and release allergic reaction media such as histamine and 5- hydroxytryptamine, which may cause allergic reactions. Expert analysis: to put it bluntly, different individuals encounter allergens and produce antibodies themselves, resulting in a series of allergic reactions. But if you come into contact with some primary substances, such as fruit acid, the chemical reaction damage can't be called allergic dermatitis. Q: What is the cause of allergic dermatitis? A: Generally, it is caused by internal and external factors. Internal cause: Allergic constitution caused by heredity plays a leading role in the pathogenesis of allergic dermatitis. Unstable internal environment, such as chronic digestive system diseases, mental stress, insomnia, excessive fatigue, emotional changes and other mental changes, as well as infectious diseases, metabolic disorders, endocrine dysfunction, etc., can induce or aggravate allergic dermatitis. External factors: including diet, inhalants, climate, exposure to allergens and other factors. Among them, seafood, spicy food, wine, inhaled pollen, dust mites, cold weather, contact with chemicals, soap and detergent are the most common causes of allergic dermatitis. Patients with allergic dermatitis have recurrent attacks due to the complicated causes and the interweaving of various pathogenic factors and inducing factors. In-depth analysis of cases by skin sensitivity experts Case 1: Xiao Liu is 25 years old and has allergic skin. For a while, I suddenly felt my skin was particularly dry. At that time, I thought it was a moisturizing cream for a few days, but it was not good. After washing my face one night in early February, I suddenly found that the skin on my face was very strange, with white lumps protruding from the surface and red spots all over my face. Expert analysis: First of all, it can be judged that this patient is allergic. "White lumps appear, protruding from the skin surface, and red spots appear all over the face", which may be a symptom of urticaria, because when the wind mass is serious, it will cause edema, squeeze blood vessels and produce white lumps. Case 2: Xiao Sha is a college student. The school has a public washing machine and often washes his clothes. Recently, I found a rash on my wrist accompanied by itching, and then the same skin symptoms appeared on my arms and back. Expert analysis: Generally speaking, bacteria in public washing machines are less likely to cause allergies. The blister on the wrist should first be ruled out as a local insect bite or scabies. Scabies can be judged by whether there are similar symptoms in armpits, joints, fingers and other skin and soft tissues. If herpes symptoms appear in a large area of the whole body, it is very likely that it is a secondary allergy caused by insect bite toxin. Case 3: I went to Maldives for a holiday in summer and came back with erythema and peeling on my back, neck, forearm extension and back of my hand. At first, I thought it was just an ordinary sunburn reaction, and then there were more serious blisters. Expert analysis: judging whether it is allergic dermatitis caused by light source mainly depends on the place where the symptoms occur. If it is only the original irradiation site, it is a common sunburn. Once systemic symptoms appear, it can be judged as light source dermatitis. This is because light irradiation on the skin changes some structures in the skin, produces antigens, and causes systemic photosensitivity reaction through the blood immune system. Treatment and prevention Q: What vitamins and minerals should allergic dermatitis supplement? A: Vitamin B: As an essential substance for skin health and normal blood circulation, it can help cell regeneration. Vitamin f: promote skin luster. Vitamin e: relieves itching and dryness of the skin. Vitamin A: Smooth skin and prevent dry skin. Vitamin D: Helps tissue repair. Zinc: Helps tissue recovery. Kelp: Kelp contains minerals necessary for tissue repair. Q: Do you still need to use skin care products during the treatment? A: It should be based on moisturizing, such as hot spring water spray containing natural minerals, which can play a soothing role. Q: How to prevent allergies caused by skin care products? A: The sensitivity caused by cosmetic ingredients is mainly determined by the sensitivity of individuals. Preservatives, fillers, hair dyes and spices are relatively more sensitive. Before using the product, it is best to test it behind the ear. Of course, it does not rule out that some people have cracks because of physical injuries and are sensitive to antigens, such as the pigment in lipstick. Q: What are the good protective measures for seasonal allergies? A: Young women's excessive protection of the skin will weaken the protective function and resistance of the skin itself, leaving the skin in a sensitive state. If you are in such a physical condition, you can wear a mask and scarf to prevent allergens. Recommended products: Yiqian Revitalizing Spray160.00/300ml; 1 15.00/ 150ml； 80.00/50ml product description: Yiquan natural isotonic hot spring water spray is rich in 1 1000mg/L minerals and trace elements, especially silicon, calcium, manganese, zinc and sodium. It can promote skin metabolism, enhance skin tolerance and protect skin from external damage. It has the effects of moisturizing, antiallergic, anti-free radical, soothing skin and delaying skin aging. Suitable for all skin types, especially sensitive skin. Recommended product: Ou Cuibi Plant Pure Repair Cleanser 235.00/500ml.