Allergies occur due to internal and external causes. The internal cause is the innate genes. Who is prone to allergies? If both parents are allergic, there is a 70% chance that the child will be allergic, but not necessarily with the exact same symptoms, for example, if the mother has allergic rhinitis, the daughter may have hives. Allergy is actually a systemic disease, but people’s symptoms are manifested in different parts of the body, where the target organ appears. For example, if it appears on the skin, it is hives, allergic dermatitis, eczema, etc. If it appears in the nose, it is allergic rhinitis; if it appears in the respiratory tract, it may be bronchial asthma; if it appears in the digestive tract, it may be allergic enteritis; if it appears in the eyes, it is allergic conjunctivitis. The external causes are related to the environment you are in. For example, the things you touch, the air you breathe, the food you ingest, and so on. Someone who was not allergic to a certain food in the past, but now has a rash all over his body when he eats it. Another person never had asthma as a child, but one day when he grows up, he has to go into the hospital because of a sudden asthma attack. Why can a person change from a non-allergic body to an allergic body? Is it possible that a person’s constitution can be transformed? There are mainly the following reasons: 1. Changes in endocrine and hormone levels lead to changes in the stress response of the immune system and induce allergic reactions. For example, pregnancy, fatigue and other conditions may cause changes in endocrine and hormone levels, resulting in changes in the stress response of the immune system. 2. The original did not have allergies, and then long-term exposure to allergens induced allergic symptoms. Many people did not have allergies before, so they usually do not care, but then suddenly found themselves allergic, in fact, you have changed the environment, long-term exposure or exposure to a large number of allergens. For example, some people were not allergic to dog and cat hair, but after buying a dog home to raise it, they are allergic to dog hair. 3, the composition of the food has changed, for example, some people eat farmed shrimp will be allergic, this is due to pollution or the impact of drugs and other ingredients added to the farming process, and eat shrimp that are not contaminated by additives are not allergic. It is recommended that for people who are prone to eating allergies, it is best to record what you eat every day so that if an allergic reaction occurs, you can find the allergen as soon as possible. Some people are particularly prone to allergies during the rapid growth period of children, adolescence and menopause, and it is advisable for them to go to the hospital for a test to see if they belong to the allergic group – first, a full body check and blood sampling to check the total IGE (immunoglobulin E); second, an allergen test (such as pollen, cat hair, dog The second is allergen testing (e.g. pollen, cat hair, dog hair, shrimp and crab), either by blood sampling or skin prick method. After detection, desensitization treatment can be targeted.