Modern medicine believes that it is because the immune system mistakenly treats some harmless substances as dangerous foreign invaders and overreacts to form allergies. When inflammation suddenly appears on the skin, such as itching and erythema, it can be judged that there is skin allergy. At this time, we must pay attention to it. If it is a sudden food allergy, it may even lead to anaphylactic shock, laryngeal edema and suffocation. Animal, plant and climate allergens are everywhere in our daily environment. Why are they allergic? Associate Professor Mao Yueping from the Department of Dermatology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University believes that one is related to external environmental factors. Spring coincides with the germination and breeding of plants. Pollen and the like are easy to float in the air, and people who are allergic to pollen become allergic after touching them. Secondly, at the beginning of spring, insects are also active, and their bodies, fur, secretions, etc. are also a common allergen. Thirdly, in spring, the climate humidity is high, and the dispersion speed of pollutants in the air is slow, so people are more likely to be exposed to pollutants for a longer time, which leads to sensitivity. Physical fitness is very important. You can't ignore skin care allergies and your own physical problems. This is very important. Professor Mao Yueping explained that if you are sensitive and easily stimulated, the chances of allergies may be multiplied when your skin is exposed to the same sensitive source compared with the normal population. In addition, skin care habits are also closely related to allergies. After the season changes, the skin care products suitable for the season are not changed in time, which makes the skin unsuitable for skin care products, and the pores of acute dermatitis are blocked and reddened, which leads to itching, which is also an allergy in a broad sense. Professor Mao Yueping told the editor that it is not necessary to do allergen testing, and the allergic constitution can be judged by experience. If you meet the following two points, you can basically judge it as allergic constitution: First, you should pay attention to whether you are prone to rash and itchy skin (something that was not originally on your skin suddenly appeared); Second, will you often get allergies repeatedly, and you have allergic experience to different varieties and different kinds of substances. To overcome allergies, it is useless to hit hard. We should try to avoid allergies as much as possible from daily scientific trials and empirical judgments. To put it simply, after learning about your allergic substances and ingredients through some life attempts, you should know how to stay away from products of the same type and similar structural ingredients, so that you can't be foolproof and take the greatest care. Xiaobian summary: people who are allergic should have a feeling of "Shennong tastes a hundred herbs" and have to overcome all difficulties to find the "grass" that they are not allergic to.