eli5: What causes you to develop allergies?



What causes your brain to develop an allergy? Is it some kind of bad wiring in the brain that causes your brain to think that a substance is an intruder, is it chemically induced through some sort of response to a chemical? I know it’s an immune system problem. I just don’t understand what causes it to develop.

In: Biology

It’s not a problem with your brain, it is with your immune system, which is a seperate system entirely.

Your immune system identifies threats via very complicated means, but put very simply it locks special cells onto proteins to see if they are compatible with the body. It can get mistaken and over defensive with some substances, and this causes an allergic reaction. It can be a mild reaction, a rash or a runny nose from a little inflammation, or it can be a fatal, systemic inflammatory response known as anaphylactic shock.