Histamine toxicity from, cases

Urticaria, commonly known as hives, is a type I allergic reaction that results very rapidly from exposure to a toxicant to which the subject has become sensitized. It is characterized by the release of histamine from a type of white blood cell. Histamine causes many of the symptoms of allergic reaction, including tissue edema. In addition to edema, erythema, and accompanying raised welts on skin, urticaria is accompanied by severe itching. In severe cases, such as happen in some people as the result of bee or wasp stings, urticaria can result in systemic anaphylaxis, a potentially fatal allergic reaction. 

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