Hives

What are hives? ​​ Hives are red, very itchy, swollen areas of the skin. Hives arise suddenly and may leave quickly in one or two hours, or can last as long as up to 24 hours. They often appear in clusters, with the new clusters appearing as other areas clear. Physicians refer to hives as urticaria. Over 20% of the population has suffered a flare-up of hives at some point in their lives.

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What causes hives? Often hives are a side effect from eating certain foods or taking medications. Foods likely to cause hives include nuts, tomatoes, shellfish, and berries. Medications often responsible for producing hives are penicillin, sulfa, anticonvulsants, Phenobarbital and aspirin.

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What are some other causes of hives? 

• Dermatographism, which occurs in 5% of the population. The hives are caused by a constant stroking or rubbing of the skin, and often occur after scratching, or when tight-fitting clothes rub the skin.

• Cholinergic urticaria (hives) is the medical profession’s term for hives that can develop after activities, which increase the body’s temperature. Activities that can cause this include a warm bath, shower, Jacuzzi, or hot tub use, exercise, a fever, or emotional stress. It has been estimated that 5% to 7% of patients who have hives experience cholinergic urticaria.

• Cold-induced hives occur after exposure to cold wind or water. Hives may appear on limbs and generally on any exposed area. Cold water or liquids can provoke symptoms on the lips or in the mouth.

• Solar hives are caused by exposure to sunlight or to a sunlamp, and a reaction can occur within one to three minutes.

• Exercise is another cause of hives. Some individuals affected can also develop lung obstruction and/or lose consciousness. Such a severe reaction is called exercise-induced anaphylaxis.

• Hives may occur in individuals regularly without obvious cause. This is called chronic urticaria (hives). Treatment for chronic urticaria includes trigger avoidance, antihistamines, and/or Xolair.