Skin allergy refers to a patient’s susceptibility to neurosensory symptoms such as itching and skin inflammation in response to a variety of environmental factors. The so-called “atopic dermatitis” includes a variety of diseases, which are briefly described below. The actual fact is that you can find a lot of people who have been in contact with a lot of people who have been in contact with a lot of people. Irritant contact dermatitis is often caused by chemical irritants, common irritants include decontaminants, acid and alkaline preparations, industrial solvents and certain plants. The patient’s skin is exposed to these strong irritants and rapidly develops a tingling, burning, itching sensation, well-defined erythema at the contact site, edema, and in severe cases, blistering, vesicles and necrosis on top of the erythema. Allergic contact dermatitis is often triggered by allergens, which are complex and varied, including metals, drugs, dyes, rubber products, disinfectants, and fragrances in certain cosmetics. Patients generally take about a week to become sensitized after first contact with the allergen, and when re-exposed to the allergen can quickly develop well-defined erythematous edema with blisters or papules, and in severe cases, large blisters, vesicles and exudates. The main symptom of the patient is intense itching rather than pain. The two types of dermatitis are sometimes clinically indistinguishable and often co-exist, when doctors often diagnose contact dermatitis. It is worth noting that the incidence of irritant contact dermatitis is much higher than allergic contact dermatitis clinically, so a large part of the allergic dermatitis we often hear about is irritant contact dermatitis, not allergic. 2, eczema Related to genetics and constitution A variety of chronic recurrent pruritic non-infectious dermatitis can be called eczema, including atopic eczema (dermatitis) and non-atopic eczema (dermatitis). Eczema differs from contact dermatitis in that the condition often has an intrinsic somatic or genetic component and is generally incurable, but can resolve over time. Atopic eczema (dermatitis) often develops in early childhood, with a small number of people developing it in adulthood. The disease is usually characterized by intense itching and dry skin, and the rash is polymorphic, i.e., a variety of simultaneous lesions, such as erythema, papules, and mossy changes, etc. The lesions often involve the folds or flexural areas of the body and often spread throughout the body. Recent studies have found that patients with this disease have defective skin barrier protein function, which makes it easy for irritants or allergens to pass through the epidermis and invite Staphylococcus aureus infection, thus triggering a skin immune inflammatory response and skin neurogenic inflammatory response, leading to a vicious cycle of itching-scratching-dermatitis. An important step in the treatment is to control the itching. In daily life, patients should avoid scalding, habitual scratching, and the use of alkaline bath products. 3, sensitive skin (syndrome) improper use of cosmetics Sensitive skin (syndrome) is due to various factors, including physical factors (sunlight ultraviolet rays, heat, cold, wind), chemical factors (cosmetics, soap, water, pollutants), psychological factors (stress, emotions), internal hormones (women’s menstrual cycle), diet (chili, wine) changes triggered by itching, burning, stinging, tingling sensation of the skin Some of them are accompanied by erythema and dry skin. This disease not only affects the face, but also the scalp, hands, and perineum. Sensitive skin is associated with modern lifestyle, where the onset of many susceptible patients is closely related to the abuse or irrational use of cosmetics, skin care products, hair dye dyes and other supplies, and may also be an early symptom of certain diseases such as atopic eczema, rosacea, and also related to mental stress.