Variable "allergies"

This is the 4948th article of Da Yi Xiao Hu

In the hospital emergency room, you can see patients coming to the hospital for various "allergic" reactions, such as those who develop rashes after taking medications, redness, itching and dizziness after eating seafood, shock after being bitten by insects, and sneezing and wheezing after inhaling pollen. In real life, allergies are always an unavoidable topic.

"Allergy" means excessive sensitivity. When the human body comes into contact with certain foreign substances, it will cause the human immune system to produce some specific antibodies. These antibodies mistake originally harmless substances for harmful things, causing the body to overreact. Because allergies have various causes and manifestations, it is sometimes difficult to judge when they come and go. It is quite confusing. Let's talk about this changeable "allergy" here.

1. There are many different allergens

Allergens are a necessary condition for the occurrence of allergies. There are 2,000 to 3,000 common antigens that cause allergic reactions, and medical literature records nearly 20,000 of them. The most effective measure to treat stubborn allergies is to find out the allergy-inducing factors (allergens), but it is difficult to accurately find the causative factors among so many inducing factors.

Based on the way the human body comes into contact with the allergens, we introduce the common allergens in real life as follows:

1. Inhaled allergens

Such as pollen, catkins, dust, animal dander, etc.

2. Ingestion allergens

Such as seafood (especially shellfish), fish and shrimp, fruits, mushrooms, beef and mutton, some medicines, etc., but sometimes it is not the food itself that causes allergies, but the additives in the food (such as disinfectants, preservatives, etc.).

3. Contact allergens

Such as cold air, hot air, ultraviolet rays, cosmetics, shampoo, hair dye, detergent, mites, etc.

4. Injectable allergens

Such as penicillin, streptomycin, xenogeneic serum, etc.

5. Self-tissue antigens

Mental stress, fatigue, work pressure, microbial infection, etc.

2. Clinical manifestations are diverse

May manifest in the respiratory tract

Such as asthma, chest tightness, nasal congestion, runny nose, etc.; skin: such as rash, erythema, itching, etc.; digestive tract: such as nausea, vomiting, diarrhea, stomach heat, colic, bloating, etc.; microcirculation and central nervous system: such as pale complexion, irritability, weak pulse, decreased blood pressure, loss of consciousness, etc.

3. Diverse Disease Types

Such as allergic asthma, allergic rhinitis, allergic conjunctivitis, urticaria, drug allergy, food allergy, solar dermatitis, allergic gastroenteritis, etc.

Although allergies vary in many aspects and different allergens manifest themselves differently in the human body, their occurrence mechanisms are the same. They all have sensitization stage, excitation stage, and effect stage. See the figure below for details.

4. What are the anti-allergic drug treatments?

1. Antihistamines

For example, second-generation antihistamines such as cetirizine hydrochloride and loratadine can prevent histamine from binding to corresponding receptors and exert an anti-allergic effect.

2. Allergic reaction media release inhibitor

For example, ketotifen is a strong allergic mediator inhibitor, suitable for the prevention and treatment of various types of bronchial asthma, and can also be used to treat allergic rhinitis and allergic dermatitis.

3. Immune regulation

For example, vitamin C can help the human body eliminate free radicals and protect human tissue cells from destruction and damage by free radicals. When the human body comes into contact with allergens, vitamin C can play its antihistamine effect.

4. Special drug treatment

Drugs such as glucocorticoids, calcium gluconate, epinephrine, etc. are mostly used for severe allergic reactions or anaphylactic shock caused by penicillin, and are used in hospitals.

5. How to prevent allergies?

1. Stay away from allergens.

2. Pay attention to your daily life, proper diet and appropriate physical exercise.

3. Improve the body's immune ability.

4. There are reports that traditional Chinese medicine, honey, cold water nasal washing, and diet therapy (such as white radish and carrot) can be used to prevent and treat pollen allergies.

Author: Shanghai Fifth People's Hospital Affiliated to Fudan University

Zhang Xuemin Chief Doctor