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Hives

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

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Hives

Definition:

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

Alternative Names:

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Urticaria

Causes, incidence, and risk factors:

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

References:

Habif, TP. Clinical Dermatology. 4^th Ed. St. Louis, MO: Mosby; 2004.

Adkinson, Jr., NFA, ed. Middleton’s Allergy: Principles and Practice, 6^th Ed. Philadelphia, PA: Mosby; 2003.

Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 17^th Ed. Philadelphia, PA: Saunders; 2004.

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