Skin allergy is a kind of allergic reaction of the organism, an abnormal reaction of the person to normal substances (allergens), which occurs only when allergens come into contact with allergic people, and there are hundreds of allergens such as pollen, dust, allogeneic proteins, chemical substances, ultraviolet rays, etc. In the process of allergic reactions, allergic mediators play a direct role. Allergens are the external cause of allergic diseases, while low immunity and oxidative damage to mast cells and basophils by a large number of free radicals are the internal cause of allergies. Beware of these 3 types of skin allergies 1, seasonal skin sensitivity Main symptoms: itching, peeling, erythema, itching of the whole body skin, especially the extremities. There are some people who have more serious skin allergy problems every time the seasons change: dryness, peeling, red spots, itching, etc. Skin sensitivity is related to dry skin, but also to the environment, climate, age, food, and cosmetics. People who are prone to allergies should pay more attention to a balanced intake of diet and nutrition, eat more fruits and vegetables, and eat less fish, shrimp, beef and mutton and greasy, sweet and stimulating foods. 2.Cosmetic allergy Main symptoms: aggravated skin allergy, skin roughness, discoloration, mostly appear in the use of cosmetics face. After the appearance of allergy symptoms, immediately stop using any cosmetics, and observe and maintain the skin care. During this period, do not wash your face with water that is too hot to avoid irritating your skin, and pay attention to sun protection. Certain ingredients in cosmetics can trigger skin allergies, stimulating skin cells and causing skin cells to produce antibodies, which can cause allergies. If skin allergy is caused by improper use of cosmetics, you cannot use ointments for general skin diseases at will, otherwise, it will cause rough skin, discoloration and aggravate skin diseases. 3, neurodermatitis Main symptoms: itching, mostly around the neck, behind the elbow, buttocks and calf side. Neurodermatitis is a common pruritic skin disease in adults, the cause is generally considered to be related to mental factors, such as emotional excitement, excessive tension at work, worry and anxiety, etc. Intense itching is the characteristic of the disease, mostly after scratching the skin thickens, but the boundaries are clear, no scales. In the early stage, the skin is light red, and later there is local pigmentation, usually around the neck, behind the elbow, buttocks and the side of the calf. So, can skin allergies be contagious? In fact, skin allergy is not contagious. There are many causes of allergy, including bad reactions to cosmetics, chemical agents, pollen, certain foods, polluted air, etc. Skin allergy, also known as sensitive skin, is a very common form of allergy, with 20% of people having skin allergies. Skin allergy mainly refers to when the skin is irritated by various stimuli and so on, resulting in abnormal phenomena such as redness, swelling, itching, peeling and allergic dermatitis. It seriously affects the patient’s appearance. What should I do if I have skin allergies? Avoid allergic and irritating foods such as fish and shrimp, coffee, alcohol and strong tea. Professor Ye Shitai, the founder of the Department of Allergic Reactions in China, once summarized four words: avoid (i.e., avoid contact with allergy-causing substances), avoid (do not contact or eat allergy-causing substances), replace (find other substances to replace allergy-causing substances), and move (get out of the allergy-causing environment). Excessive scrubbing, violent scratching, avoiding all kinds of external stimuli such as hot water scalding, etc. There are many patients who use hot water to scald themselves repeatedly, some even use salty salt water, pepper water to wash, or simply scratch desperately until they scratch and bleed, although these measures are effective in a short period of time, however, once they stop, the itching will become more and more itchy; and the above actions or methods only transform the itching stimulus into a painful stimulus. Painful stimulation, eventually causing local skin hyperplasia hypertrophic infiltration, nutritional changes, but will aggravate the itch; so vicious circle, will make the skin disease gradually worsen.