Hives

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Food allergies	Hives	Hives (urticaria) - close-up	Hives (urticaria) - close-up
Hives (urticaria) on the arm	Hives (urticaria) on the back	Hives (urticaria) on the back and buttocks	Hives (urticaria) on the chest
Hives (urticaria) on the chest	Hives (urticaria) on the trunk

Hives are raised, often itchy, red welts on the surface of the skin. They are usually an allergic reaction to food or medicine.

Urticaria

When you have an allergic reaction to a substance, histamine and other chemicals are released into your bloodstream, causing itching, swelling, and other symptoms. Hives are a common reaction, especially in people with other allergies like hay fever.

When swelling or welts occur around the face, especially the lips and eyes, it is called angioedema. Swelling from angioedema can also occur around your hands, feet, and throat.

Many substances can trigger hives:

• Medications
• Shellfish, fish, nuts, eggs, milk, and other foods
• Pollen
• Animal dander (especially cats)
• Insect bites

Hives may also develop from:

• Infections like mononucleosis or illness (including lupus, other autoimmune diseases, and leukemia)
• Emotional stress
• Extreme cold or sun exposure
• Excessive perspiration

Review Date: 07/22/2005
Reviewed By: Jonathan Kantor, M.D., Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.