Why is there a red pimple on the leg when it is cold in winter, and it is a little itchy?

Skin allergy is also called "sensitive" skin. From a medical point of view, skin allergy mainly refers to the abnormal phenomena such as redness, itching, peeling and allergic dermatitis when the skin is stimulated by various cosmetics, chemicals, pollen, certain foods and polluted air. Sensitive skin can be said to be an unstable skin, which is always in a state of high alert. Special attention should be paid to its care. Why does the skin have skin allergy? 1. With the increase of age, the secretion function of the skin will deteriorate, the skin will become thinner with the passage of time, and its protective layer function will also weaken. 2. Long-term exposure to sunlight or air pollution, smoke, dust, ultraviolet rays UVA, UVB and infrared rays will damage the skin, because the free ions they produce will damage the lipid protective layer of the skin. 3. Improper damage of inferior cosmetics or drugs. 4. Physiological factors, stress, mental stress and depression will weaken the natural resistance of the skin and slow down its self-repair function. Such as endocrine disorders. 5. Weather: In the face of weather changes, the skin also needs extra adaptation. For example, in cold weather, if the skin is not adequately moisturized, it is very vulnerable. 6. Additives: Some ingredients in skin care products, such as preservatives, dyes, emulsifiers, spices, etc., may make the skin sensitive. 7. What contingency measures should be taken for specific physique allergic to skin? 1, all cosmetics should be stopped to give the skin a buffer time. If you usually use low-sensitivity skin care products, you can continue to use them; If it is the first time or occasionally allergic phenomenon, and you don't use low-sensitivity skin care products on weekdays, then you should choose special skin care products with anti-inflammatory and calming effects and use them after washing your face with water. If there is persistent redness, you should go to the hospital for desensitization treatment. You can also fully moisten normal saline for injection and apply it to sensitive parts of the face with cotton or gauze. This normal saline for injection has high safety and good permeability, and has the functions of detumescence, detumescence and skin stabilization. Generally speaking, the red will disappear in a few days. 2. Strengthening skin resistance is also an effective basic countermeasure, such as adequate sleep, adequate and balanced diet, harmonious mood, staying away from polluted environment and allergens, and reducing skin irritation. Mild sensitivity will recover quickly as long as it is handled properly, and you need to seek medical advice quickly when it is serious. 3. Don't use drugs without authorization. Don't go to the drugstore to buy the attached corticosteroid ointment without a dermatologist's diagnosis, which is harmful to the skin. Because it is effective in inhibiting inflammation, but long-term use will have side effects and endanger health. Treatment of skin allergy: The diseases caused by skin allergy are not rashes, including urticaria, contact dermatitis and atopic dermatitis. Because some of these diseases, such as contact dermatitis, are at different stages of development, the principle of medication, especially the principle of external use, is completely different, and if not handled properly, it will aggravate the symptoms; Although some diseases such as urticaria can heal themselves, if the condition is serious, it may cause laryngeal edema and anaphylactic shock. Therefore, Wang Dafu suggested that patients can take oral antihistamines to treat themselves unless they have mild urticaria. In other cases, especially when the symptoms are still not relieved after taking the medicine, you must go to the hospital for treatment instead of saving trouble for a while. For topical hormone drugs for the treatment of skin allergy, such as Piyanping, Youduolu (hydrocortisone butyrate) and Elosone (mometasone furoate), it should be noted that: 1. Don't apply it to your face, because these drugs will cause epidermal atrophy and pigmentation, which will cause irreversible damage to facial skin. 2. It should be used after a doctor's definite diagnosis, because these drugs are not effective for all skin itching. Treating skin allergy by mistaking tinea corporis and scabies for allergies is a very common misunderstanding in patients' self-medication. 1, away from allergens. Because allergic symptoms will always exist, it is impossible to cure them. You can only take preventive measures at any time to avoid contact with allergens that may cause allergies. 2. Be clear about the skin care products you use and their usage. Avoid using substances with strong curative effect and excessive activity that may irritate the skin. Excessive and improper use of powerful cleaning products will destroy the natural protective tissue on the skin surface; Cosmetics that are too active and will accelerate blood circulation will also irritate the skin and cause harm. Don't wash your face with soap-based emulsion such as medicated soap, because surfactants are experts in decomposing keratin and should be avoided as much as possible. It is best to use emulsion or soap-free soap to adjust the pH and adapt to the skin. Products such as scrub and exfoliating agent should keep a certain distance from others. Adopt simple cleaning, refreshing and moisturizing procedures. 3. Pay attention to the use of sunscreen products. Sensitive skin has a thin cortex, has no defense against ultraviolet rays, and is prone to aging. Therefore, it is better to wear basic skin care products as isolation before using sunscreen, but the ingredients of sunscreen products are also one of the factors that are easy to cause irritation, so it is best not to apply them directly to the skin surface. Recently, some manufacturers have introduced sunscreen products with less chemical and physical components, which are relatively less irritating to the skin. At the same time, avoid excessive exposure, because ultraviolet rays are particularly penetrating, and frequent exposure will make the skin thinner and more vulnerable to irritation. 4. Use cosmetics with caution. For people with sensitive skin, it is best not to change used cosmetics casually. If you want to use new cosmetics, do a skin test first. The method is to smear cosmetics on the delicate skin inside the wrist and leave it for one night or 2-3 days to observe its reaction. If there are abnormal reactions, such as inflammation, redness and rash, you must avoid using cosmetics. People with "sensitive" skin should wash their skin with warm water. In areas with flying pollen in spring, we should try our best to reduce going out to avoid causing pollen dermatitis. Moisturizing cream can be used in the morning and evening to keep the skin moist and prevent the skin from drying and peeling. 6. In diet, eat more fresh fruits and vegetables and have a balanced diet. It is best to include a large number of fruits and vegetables rich in vitamin C and any food containing vitamin B, and drink more clean water, which can moisturize the skin in the body in addition to various benefits. Usually do some nutritional masks, such as cucumber juice mask, loofah juice mask, egg white honey mask and so on. In order to gradually improve the skin condition and get skin fitness. 7, carry-on clothes should be rinsed clean, and the residual detergent in the clothes towel may irritate the skin. 8, sleep has a cosmetic effect, eight hours of full sleep every day, no skin care products can be replaced. 9, exercise can improve blood circulation, enhance skin resistance, and enter the best state.