A very common category of diseases in dermatology is called “allergy-related skin diseases”, such as eczema, dermatitis, urticaria, cosmetic dermatitis, hair dye dermatitis, etc. In many cases, when encountering these diseases, hospitals always issue some “allergen tests”. “But these tests are generally expensive, so what exactly can be tested by “allergen testing”? When is it really necessary to test for allergens? How do we interpret the results of an allergen test when we get one? Let’s talk about it today. Let’s answer the first question first: there are many types of allergen tests, the common ones are: allergen inhalation and ingestion group screening test, skin patch test, skin scratch test, intradermal test and so on. Most hospitals conduct blood sampling programs, of which the “allergen inhalation and ingestion screening tests” are the most common. Most of the tests include: inhalation group such as household dust mites, cat and dog dander, mold, cypress, willow, poplar and mulberry, artemisia, etc.; inhalation group such as milk, egg white, crab, shrimp, shellfish, beef and mutton, mango, pineapple, cashew nuts and peanuts, etc., as well as grading and values, and finally, the total IgE value is generally added. The content of these allergens selected above is a large-scale clinical research done to list the most allergy-prone representative things, for example, cat and dog dander is the representative of animal dander, crab, shrimp and shellfish is the representative of seafood food, cashew nut and peanut is the representative of nut food, etc. The value of IgE also reflects the degree of allergy, generally the higher the value, the heavier the allergy status (normal people). The higher the value, the more severe the allergy status (less than 100 for normal people). These are the items that can be tested in general. So, let’s gather our attention to the second question. Theoretically, allergen testing can be done for the diagnosis and prevention of any allergic disease. My suggestion is that patients with high suspicion of allergy to a substance, those with allergic diseases of unknown cause who need some guiding opinion, those with suspected occupational allergic dermatitis, and those with allergic dermatitis who are resistant to all kinds of treatment can do this test. Finally, a few representative questions that people often ask are summarized to understand some of the ways to interpret allergen test results: 1. Last week, little Nan Nan had frequent hives and was allergic to “dust mites” in the allergen test, so her mother was helpless. In fact, there are tricks to this. For example, avoid letting the child enter a room that has not been lived in for a long time, fully ventilated before entering; avoid using a broom to sweep the floor, try to mop the floor with a mop to avoid dust; if the child has the habit of holding the doll to sleep, must be cleaned and diligent sunlight; and so on. 2, less than three years old, recently eczema aggravated, I gave him allergen testing, the results of “fish, shrimp and crab” allergy, but the child’s parents are southerners, seafood is often eaten food, the family is now anxious. In fact, the allergen test is just a tip, take fish, there are too many kinds in nature, and each kind of fish contains different proteins, raw fish and cooked fish are also different, positive results do not necessarily can not eat. My advice to the father is: first use river fish for your child, choose one, cook it sufficiently and then give it to your child for trial, if the eczema does not worsen, you can still eat it later. For the same reason, you can try prawns, crabs, etc. Here I still want to emphasize that it is not that positive foods in the allergen test must not be eaten, it should be interpreted as a hint. 3. My colleague Yanxia just had a baby, 4 months old, with baby eczema since birth, which worsened in the last week, with obvious oozing and crusting. After carefully asking about her medical history, I found out that Yanxia was busy at work and recently wanted to “wean” her baby, so she added milk powder to her diet. Because we know that the protein in milk is a large molecule, it is easy for babies to develop allergies. Combined with the results of allergen testing, I suggested that the formula be changed to hydrolyzed protein formula for 2 weeks to strengthen the treatment of eczema, and the child’s eczema improved. It is worth mentioning that there are many hydrolyzed protein milk powder on the market now, such as Newcomer and Nestle Eneminshu, with deeply hydrolyzed protein and partially hydrolyzed protein, so you should choose according to the actual situation of your child. 4, finally, a brief mention of other types of allergen testing experiments: patch test is generally used mostly in the screening of suspected exposure to allergens, such as itchy scalp after changing shampoo, glasses leg dermatitis appears after wearing glasses, etc.. These are the ones that must go to the professional dermatology or allergic reaction department to do the relevant test identification. Skin scratch test and intradermal test are invasive operations, so children need to be careful when using them. Some highly allergic people need to be used under conditions of resuscitation facilities.