Dictionary Definition:
noun
1: hypersensitivity (as to foreign proteins or drugs) resulting from sensitization following prior contact with the causative agent~ merriam-webster
Elizabeth's take on this term...
Severe acute inflammation may manifest as anaphylaxis, or swelling of the airways that inhibits breathing, and is a severe result of an allergic reaction that can result in sudden death from eating a peanut or a shrimp, or even getting stung by a bee, for those who are sensitive to those substances.