Low immunity means that when the body is in a state of deficiency of positive energy and qi and blood, its own ability to resist evil decreases, and external evil invades the body, which can cause a series of diseases or symptoms, such as frequent late nights, exertion, emotional depression, or after a major blow, the body’s ability to resist evil decreases, and low immunity can easily cause infections of the upper respiratory tract, digestive tract, or urinary tract, such as swollen tonsils, frequent colds, pneumonia, there may be the appearance of abdominal pain, diarrhea, chronic enteritis, and also urinary tract infections such as frequent, urgent, and painful urination. Through different symptoms and different tests, it is possible to find out where the different disease evils are located and to carry out targeted treatment. Low immunity not only has infectious problems, but also may have endogenous immune function problems, such as chronic nephritis and nephrotic syndrome, and immune rheumatism-related diseases in the body, such as bone and joint pain, rheumatism and rheumatoid diseases, which are all formed because of the decline of autoimmunity, insufficient ability to resist evil, and a mixture of internal and external causes. When the immunity decreases, there will also be allergic reactions, such as the appearance of respiratory asthma, which originally did not have any reaction to a certain substance, but, when the body’s immunity decreases, the symptoms of asthma will appear; or the body will develop itchy rash, hives; or there are irritating smells such as decoration around, which will also trigger some symptoms in the body. According to the different symptoms, to know whether you are in a state of immunity decline, you need to go to the hospital for timely examination, improve immunity, timely treatment, and increase your ability to resist evil.