The use of skin care cosmetics can moisturize the skin, especially with some cosmetics containing nutritional ingredients, which can make the skin soft and stretchy and slow down the aging process; some professionals use some beauty cosmetics appropriately, which can give people a kind and beautiful impression; and some cosmetics can treat certain skin diseases, such as pigmentation spots, acne, etc. But everything is divided into two, cosmetics have various advantages, but there are also many disadvantages, especially some cosmetics can cause certain skin diseases. With the improvement of people’s lives and the increase in the use of cosmetics, cosmetics have caused an increasing number of skin diseases, which must be taken seriously. 1, the reason 1, allergic reactions: cosmetics consist of a variety of raw materials, many of the ingredients, such as fragrances, dyes and preservatives, may make some people have an allergic reaction, such as the more common hair dyeing dermatitis is caused by allergies to the hair dye in the paraphenylenediamine. 2, photosensitive reactions: certain ingredients in cosmetics, especially fragrances, are photosensitizers, after using increased skin sensitivity to light, can also cause skin disease in exposed areas. 3, primary irritation: that is, anyone who is exposed to it can react, such as the chemical peeling (commonly known as snow skin surgery) of carbolic acid, trichloroacetic acid is such, after the application of the skin surface necrosis, scab off, part of the skin disease also fell off, such as freckles, age spots, etc.. However, some people have large pigmentation after the scabs fall off, which does not subside for a long time. 4.Toxic reactions: If poor quality cosmetics contain lead, mercury, etc., long-term use can cause systemic toxic reactions, skin pigmentation, flaking and skin roughness. 5, pore blockage: some people, especially some actors, long-term use of oil, which the oil, pigment particles can block the pores cause acne. Second, common cosmetic skin diseases caused by 1, contact dermatitis: in the application of cosmetics caused by redness, papules, small blisters, etc., serious can be red, swollen, blistering, ulcerated ooze. This is mostly caused by allergic reactions, usually the first contact, after 4 to 7 days incubation period before the onset of disease, re-contact generally in a few hours onset. Patients feel itchy or burning pain on the skin, and in severe cases there may even be a generalized fever and discomfort. Most patients recover gradually after 7 to 10 days. Contact dermatitis caused by hair dyeing, however, can be delayed until one or two months because the dye adheres to the hair and is not easily washed away, and the allergen is not removed. As for photosensitive dermatitis, it is the application of cosmetics, dermatitis occurs only after exposure to light, mostly seen in the cheeks and forehead and other exposed areas. 2, acne, acne: a part of the original acne, often use cosmetics after the rash more serious, such as into red papules, pustules and even hard nodules, and some of the original does not have acne, but often after makeup, acne, acne, most of these are theater actors often use oil paint, become an occupational skin disease. 3.Pigmentation: Some of these occur after a cosmetic treatment, such as liquid nitrogen freezing or chemical peeling, and produce pigmentation spots. Some others occur after frequent recurrence of contact dermatitis, especially some old actors. However, some of them also occur gradually without knowing it. It occurs mainly on the forehead, around the eyes and cheeks, and appears as light brown to brownish-black spots. Except those caused by chemical exfoliation, the edges are often unclear, and sometimes the pigmented spots in the temporal area and in front of the ear show a mesh-like appearance, and the surface may have a little fine flaking, just like a layer of flour-like sprinkling, which is called melanosis. 4.Itching: This is a lighter reaction, that is, every time after applying cosmetics, the skin feels itchy, but not a rash, and the itching disappears after washing. The first thing to do is to stop using cosmetics or switch to other brands of cosmetics, and generally light cosmetic dermatitis will subside on its own after a few days of disuse. The actual fact is that you can find a lot of people who are not able to get a good deal on a lot of things. 3, the occurrence of dermatitis at the light only erythema, papules, can apply zinc oxygen brush or furnace glycerine brush, local redness and swelling of water can be 1 ~ 3% boric acid water wet compress. 4.For hyperpigmentation spots, vitamin C can be taken internally or injected intravenously, while rubbing some blemish removal cream. 5, on acne, acne is often used warm water sulfur soap wash face, can rub compound sulfur lotion, retinoic acid, benzoyl peroxide or 20% azelaic acid cream. The skin tolerance of each person is a little different, and imported cosmetics add more chemical ingredients, after the application of allergic reactions are more. Therefore, according to their own economic conditions, try to use some of the old domestic production of cosmetics, because the old brand or brand-name products are mostly long-term sales, good results, to get the trust of the public to endure, to become a brand-name.