What type of reaction is a hypersensitivity to an allergen such as bee sting?

A hypersensitivity to an allergen such as a bee sting is an example of a type I hypersensitivity reaction, also known as an immediate hypersensitivity reaction or an anaphylactic reaction. This type of reaction is characterized by the release of histamine and other inflammatory mediators from mast cells and basophils after exposure to a specific allergen.