Asthma is an allergic disease, the internal cause of the disease is “allergy”, and the external cause is various allergens. The first principle of treatment is to get rid of allergen exposure. Many patients diagnosed with asthma for the first time will naturally think: identify the type of allergen as soon as possible and try to avoid it in the future so that asthma can heal itself. Is it really that simple? Allergies are genetically determined, genetically predisposed, and inherent. But when do allergic symptoms appear in the body? Where do the allergy symptoms occur? What is the severity of the symptoms? There are many environmental factors that influence the degree of allergy. This is why some people develop allergic rhinitis and eczema in childhood, while others develop symptoms at the age of 50 or 60. Do some people have severe symptoms? Do some people have mild symptoms? There are many kinds of allergens, the following are common in life: (1) mites: the dust mite under the microscope is about 0.33mm long, it grows and reproduces by eating the skin scales shed by the human body every day, so there are more dust mites in the bed, which is also the reason why children have more asthma attacks at night. Dust mites grow best in warm and humid seasons. Therefore, dust mites should be avoided by reducing the relative humidity. In addition, there is usually a large amount of dust mite antigen in old dust in the home because dust mites deposit their body debris after death in dead dust that is not normally cleaned. (2) indoor fungus: the main allergenic human is mold. Indoor fungal levels are related to the age of the housing, the heating system and the presence or absence of humidifiers and air conditioning units. Dark, damp, poorly ventilated living rooms, especially basements, are ideal places for fungal growth, followed by bathrooms and kitchens. Humidifiers and air conditioning units can also become places for fungal growth, home environment is damp, overcrowded home is easy to cause asthma in children. (3) silkworms: silk and cotton are mainly used as fillers for winter clothing and are woven into sweaters and carpets, so it is an important cause of asthma attacks in winter. Silk, due to multiple processing rarely induces allergies. Silkworms are completely metamorphic insects, and there is cross-reactivity between silk and other forms of silkworms, such as cocoons, young silkworms, silkworm urine, pupae and scales of silkworm moths, thus people allergic to silk can be allergic to any form of silkworms. (4) Animal-related allergens: Indoor animals, especially dogs and cats, are a common cause of allergic rhinitis and asthma. When a dog or cat enters the home, patients allergic to them can develop the disease within minutes. Woolen sweaters and pants made of wool have been processed several times, and allergenicity has been greatly reduced and rarely causes allergies. Cockroaches, which are commonly found in kitchen cabinets and bathrooms, are also common inhalation allergens. However, it should be noted that irritating chemical pesticides can also induce allergic symptoms. (5) Pollen: Pollen is generally common outdoors. The pollen of three major types of plants, trees, forbs and weeds, is spread by the wind, and these phoenix-borne pollens dispersed in the air are the main source of airborne allergens. These pollens are fragrance-free, large in quantity, light in weight, and extremely widespread, and can drift with the wind to high altitudes and to distant fields and towns, and are the main pollen that induces allergies. Wind-borne pollen in spring mostly comes from trees, such as pine, cypress, poplar, acacia, willow, birch and other pollen in the air for a short period of time, more than ten days can pass, causing lighter symptoms and a shorter duration. Late spring and early summer wind-borne pollen is mostly from pasture. Wind-borne pollen in late summer and early autumn comes from weed species, and is most common in China with Artemisia absinthium. Grass pollen drifts for a long time, causing heavy symptoms, and the symptoms last for a long time, about a month or so. And 90% of hay fever is caused by pollen in summer and autumn, so many kinds of allergens, some allergens such as: dog and cat fur, it is easy to avoid. However, most allergens, such as pollen, mites, and fungi, are highly concentrated and widely distributed, so it is difficult to completely avoid them. Moreover, many patients are sensitive to multiple allergens, so it is difficult to expect to cure allergic diseases through the method of complete disconnection from allergens. Since this is the case, is it possible to get rid of these allergens completely through desensitization? Desensitization therapy, also known as specific immunotherapy, is practical and can stall the worsening of symptoms and prevent the development of allergy to new allergens. Desensitization involves making injections or oral preparations of known allergens and giving them subcutaneously or orally and sublingually on a regular basis to create immune tolerance in patients, which can reduce the symptoms and attacks of allergy. The complete course of desensitization therapy takes 3 to 5 years. Several studies have demonstrated that successful desensitization therapy can free patients from drug dependence for up to 8 years. However, there are only a limited number of allergens that can be desensitized, and the only internationally recognized technically mature desensitization reagents are dust mites and some fungi, which means that desensitization can only be successful if the patient is sensitive to only these two allergens. However, most allergic patients are allergic to multiple allergens at the same time, and desensitization to only two allergens is as effective as one can imagine. This is the reason why desensitization is not the preferred method of treatment for allergic diseases at this time. So, is there any value in checking for allergens and performing desensitization therapy or not? Of course there is. When the first diagnosis of asthma is made, patients should check the allergen types in detail so that they have a good idea of what to expect. When there are easily avoidable types of allergens such as cat hair and dog hair in your allergen profile, you should avoid them completely in the future. Keep doors and windows tightly closed. When you find that you are allergic to mites only, you should take desensitization treatment.