Symmetrical rash on both arms

Rash is a manifestation of many skin diseases. The nature of the rash can be judged based on its characteristics, the location of the rash, and the presence or absence of pain. The symmetrical red rashes on both arms are most likely caused by allergies. We can start with the analysis of the allergy situation and make a judgment based on our own situation to find the ultimate cause. So, what's the matter with the symmetrical red rashes on both arms? Let’s take a look below.

The causes of allergies can be roughly divided into two types: external factors and internal factors.

1. External factors

Certain substances can cause abnormal reactions in some people's immune systems after entering the human body. These substances are called "allergens (also known as allergens)" and are the culprits of allergies. Allergens are mostly large molecules, such as certain proteins or peptides. Common allergens include food (wheat, peanuts, soybeans, nuts, milk, eggs, fish and crustaceans, etc. Allergic diseases caused by food allergies account for about 90% of the total allergies), inhalants (pollen, house dust, mites, etc.), microorganisms (molds, bacteria, etc.) and insect toxins, drugs (such as penicillin, sulfonamides, etc.), xenobiotic sera and physical factors. The above substances can enter the body through ingestion, inhalation, contact and injection. Large molecules act directly as antigens, and small molecules (haptens) can combine with certain substances in the body to form new antigens (allergens). When allergens enter the body for the first time, they can cause sensitization in the body. When these substances enter the body again, allergic reactions will occur. It stimulates abnormal activity of the patient's immune system, ultimately causing a series of allergic injuries.

2. Internal factors

Not all people are allergic. Some people are allergic while others are not under the same circumstances - this fact tells us that the occurrence of allergies requires internal factors. The internal cause is the "allergic constitution" of some people. Allergic constitution refers to the defective immune system of a certain group of people. Their immune system is different from that of ordinary people, so they are prone to "not distinguishing between friends and foes and attacking without reason", which leads to the occurrence of allergies. Allergic diseases are mostly hereditary. If both parents have allergic diseases, 75% of their offspring are likely to develop allergic diseases, 50% of which occur in the first five years after birth. As age increases, the incidence of allergies will gradually decrease.

In recent years, with the accelerating process of industrialization, urbanization and globalization, people's pace and way of life are constantly changing, life and work pressure is increasing, and there are more and more types of food and processing techniques. As a result, many people who were not allergic before may gradually evolve into people with allergies, and the number of potential allergic people continues to expand. At the same time, with the improvement of science and technology and medical level, many previously unrecognized allergic phenomena have also been revealed. This is why the occurrence and discovery of allergies are increasing.