If our bodies come into contact with substances that are alien to them or could pose a potential danger to them, they trigger a defence process. One of these substances is allergens. These are primarily tiny proteins that, generally speaking, do not constitute a threat to the organism.
However, people with allergies develop special antibodies which lead to the release of various tissue hormones in our skin and mucous membranes. The most important of these hormones with regard to allergic symptoms is histamine: it is responsible for many of the body's allergic reactions, e.g. itching, shortness of breath or increased dilation of blood vessels.
The immune system is activated the first time the body experiences the allergen. This process then occurs every time a new contact takes place. This means: if the body has reacted allergically to a substance once, it never forgets. In other words, repeated contact with the substance leads very quickly to an allergic reaction – usually in a matter of minutes, but it can sometimes take up to one hour.
The reaction of the eyes is particularly severe; the conjunctiva and mucous membrane react immediately to the foreign substance, the blood vessels dilate and fluid is released. We experience this in the form of tears, a runny nose, swelling or reddening. The tears gradually flush the allergens out of the eyes, therefore slowly alleviating the symptoms.
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