What does the term 'allergic reaction' refer to?

The term 'allergic reaction' refers to a body's exaggerated immune response to an agent, typically a substance that the immune system mistakenly identifies as harmful. This response can occur in various ways, including through symptoms like itching, rash, swelling, and even anaphylaxis, which is a severe, potentially life-threatening reaction.

In an allergic reaction, the immune system produces specific antibodies known as immunoglobulin E (IgE) that react to allergens, which are usually harmless substances like pollen, pet dander, certain foods, or medications. The exaggerated nature of this response can lead to inflammation and symptoms that can significantly affect an individual's quality of life or require medical intervention.

Normal immune function involves recognizing and responding to pathogens without excess or harmful reactions, while tissue necrosis refers to the death of cells or tissues due to injury or lack of blood supply, neither of which describes an allergic reaction. A fatal drug interaction, on the other hand, usually involves a chemical interaction between medications that can lead to severe adverse effects but does not specifically characterize the body's immune response to allergens.