Hives are small, itchy, red swollen areas on the skin. The swelling occurs singularly or in clusters. Hives tend to fade after a few hours, but new ones can appear. Most cases go away within a few days. However, some last a few weeks or longer.
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Hives are often caused when the body releases a chemical called histamine. Histamine is released during an allergic reaction. Many people, though, get hives without being exposed to something they are allergic to.
While the cause is unknown in some cases, these factors may cause hives:
Factors that may increase your risk of hives include:
Symptoms of hives can vary from mild-to-severe:
You will be asked about your symptoms and medical history. A physical exam will be done. You may need to see a doctor who specializes in skin disorders (dermatologist) or allergies (allergist).
Your bodily fluids and tissues may be tested. This can be done with:
Images may be taken of your bodily structures. This can be done with x-rays.
The best way to treat hives is to find and then avoid the cause.
If the cause can't be found, there are medications to reduce symptoms or treat hives:
The best way to prevent hives is to avoid the allergen that caused you to get hives in the past.
American Academy of Allergy, Asthma, and Immunology
American Academy of Dermatology
Canadian Dermatology Association
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Last reviewed September 2015 by Marcin Chwistek, MDLast Updated: 9/30/2014