Here’s another common question, and an important one for allergy sufferers and people considering immunotherapy. In order to better understand this, you must first understand a few things about the human immune system.
The primary purpose of the immune system is to fight infection from bacteria, viruses, and parasites. In order to do this, the immune system must be able to distinguish 1) self from non-self and 2) normal environmental substances from abnormal environmental substances. When the former breaks down, you get autoimmune diseases such as lupus, rheumatoid arthritis, type I diabetes, and the like. In these diseases the immune system actually attacks the body, causing injury and disease. When the latter breaks down, you get allergies.
In an allergic reaction, the immune system incorrectly recognizes a harmless environmental substance, like cat dander or ragweed pollen, as a potentially harmful substance. In an attempt to rid the body of the offending substance, the immune system attacks it by releasing toxic chemicals- histamine, leukotrienes, platelet activating factor, prostaglandins,and other 50-cent words. It is the release of these substances that gives you allergic symptoms- sneezing, runny nose, itchy eyes, congestion, wheezing, hives, etc.
Allergy shots teach the immune system to no longer recognize these harmless substances as harmful. Allergists call this inducing tolerance. This stops the allergic reaction before it ever starts and works to control allergy symptoms globally, whether they be in the eyes, ears, nose, throat or lungs. Allergy shots also help to control the whole body symptoms of allergies such as fatigue, malaise, and sleep disturbance, that medications do a very poor job of controlling.
The immune system is incredibly complex so if this explanation isn’t clear, please ask questions and I’ll try to clear up any confusion.