Definitions

• Anaphylaxis: A life-threatening type of allergic reaction.
• Localized Hives: Hives on one area of the body only. Localized hives are usually due to skin contact with plants, pollen, food, a chemical, or pet saliva. Localized hives usually resolve in less than 4 hours.
• Widespread Hives: Hives on multiple (2 or more) areas of the body. Widespread hives can be an allergic reaction to a food, cosmetic product, drug, insect bite, or other substance. Sometimes widespread hives show up after a viral infection. Often the cause is not found.