**5. Hypersensitivity or inflammatory allergic reactions**

The damaging immunologic reactions are called as hypersensitivity reactions. Although, current understanding of allergic diseases has grown vastly since then, this classification system remains useful even today. The 4 types of hypersensitivity reactions are; immediate hypersensitivity (type I) reactions, cytotoxic (type II), Ag-Ab complex mediated (type III), and T cell-mediated (type IV) delayed hypersensitivity [11]. The IgE mediated acute and immediate hypersensitivity reaction is the dominant out of the four types and forms the basis of allergic reactions that trigger and responsible for all allergic symptoms.
