Hives are small, itchy, red swellings 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.
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:
A risk factor is something that increases your chance of getting hives. Tell your doctor if you have any of these:
Symptoms of hives can vary from mild-to-severe:
The doctor will ask about your symptoms and medical history, and do a physical exam. You may need to see a doctor who specializes in skin disorders (dermatologist) or allergies (allergist). The following tests will be done:
The best way to treat hives is to find and then avoid the cause.
If the cause can't be found, there are medicines to reduce symptoms or treat hives:
The best way to prevent hives is to avoid 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 2012 by Purvee S. Shah, MD
Last Updated: 09/10/2012