Sensitive skin Sensitive skin is a new term that has emerged in recent years, usually referring to a self-perceived inability to tolerate any of the treatments and cosmetics applied to the skin. Epidemiological surveys of consumers in different countries and different races show that consumers who consider themselves to have sensitive skin account for almost 1/4-1/2 of adults. The causes are still unclear, and the results of the survey show that: changes in temperature, sun exposure, spicy and stimulating food, cosmetics, and unorthodox skin care are the main causes of skin sensitivity; pollen, high-protein foods, house dust, dust mites are the main allergens; nickel sulfate, formalin, and dust mites are the main allergens; nickel sulfate, formalin, and dust mites are the main allergens. Allergen; nickel sulfate, formalin, and white mercury is directly caused by skin sensitivity of the material; about 30% of the subjects in the allergy test in the wave ultraviolet positive, clinically hormone-dependent dermatitis, laser surgery and external stimulation of the drug, often lead to skin sensitivity. Sensitive skin people with facial skin oil, moisture, lower than healthy skin, may be caused by internal or external factors such as multiple factors separately or together after the integrated performance, the main mechanism is the skin barrier function is impaired, the sensory nerve signal input increased and the enhancement of immune response. Therefore, sensitive skin should use gentle, single ingredient medical skin care products designed for sensitive skin for skin care. Currently, natural ingredients, such as spring water or natural plant extracts, are mostly used in medical skin care products. Living spring water can not only be used for a variety of inflammatory skin diseases, but also for a variety of post-operative skin care (surgical excision suture, electrocoagulation surgery, photorejuvenation, etc.) Dry skin (eczema, hyperpigmentation, skin aging) Normal stratum corneum in the lipids, natural moisturizing factors so that the stratum corneum to maintain a certain amount of water content, stable water and the state of the stratum corneum to maintain the normal physiological function of the necessary conditions. The stratum corneum can keep the water loss of the skin only 2-5g/(h.cm), so that the skin is smooth, supple and elastic. If the natural moisturizing factor in keratinocytes and sebum secretion is reduced, the water content of the stratum corneum is less than 10%, the ph value is greater than 6.5, and the skin is dry and flaky, which is called dry skin. On the basis of dry skin, it is easy to appear lack of sebum eczema, hyperpigmentation, skin aging and so on. Many skin diseases are associated with epidermal barrier dysfunction, which can lead to destruction of epidermal intercellular lipids, reduction of natural moisturizing factors, and loss of cell-to-cell adhesion under certain exogenous and endogenous factors. A large amount of water escapes and is lost from the dermis and epidermis. Transcutaneous water loss (TEWL) increases,, scaling, cracking, and the formation of dry skin disease. Dry skin of the stratum corneum water content is reduced, keratinocyte function and structural disorders, can not melanin timely and uniformly sent to the epidermis, and sebaceous gland secretion is reduced, is the epidermis with the role of sunscreen squalene and other content is reduced, resulting in weakening of the skin’s function of sunscreen, resulting in melanin metabolism disorders, the skin lacks elasticity, which can lead to aging of the skin and wrinkles increase. Oily skin (acne, seborrheic dermatitis, rosacea) The sebaceous glands have the ability to secrete sebum, lubricate the skin, inhibit the growth of fungi and bacteria, and at the same time absorb fat-soluble substances, which have a certain effect on the ph value of the skin surface. However, if sebum secretion is excessive, coupled with changes in environmental factors and microbial infections, skin diseases such as acne, rosacea, and seborrheic dermatitis are likely to occur.