eli5. Why is it that you don’t have a reaction to something for the first time if you are allergic to it?

Question

For example if you eat something that you are allergic to for the first time, nothing will happen. But the second time you’ll have a reaction.

In: Biology

Answer 1

An allergic reaction is an inflammatory response as part of your immune system. While your immune system is good at fighting off new antigens, where it excels is with secondary exposures. Memory cells and antibodies are ready and will initiate that cytokine cascade and the inflammatory response.

Edit: wording is hard