What are hives?

Hives are raised welts that can appear anywhere on your skin and are usually itchy. The medical term for hives is urticaria. Hives are usually red or skin-colored, and they vary in size from a pea to a dinner plate. Hives are most often triggered by the release of histamines in the skin, which causes localized swelling, burning and itching. Hives can result from allergic reactions or may be due to many other conditions.

Skin Problems Spotlight

Individual welts or spots usually will not last more than a day, though new hives may appear, and the general condition can last for weeks depending on the cause. Many hives may join together to form a very large welt. Scratching, compressing, heating or cooling hives excessively can worsen them.

Though itchy and uncomfortable, hives are usually self-limiting and disappear on their own. In rare circumstances, hives can be a sign of a more serious allergic reaction. A visit to your health care professional may help to determine what triggered your hives, though the exact cause is usually difficult to determine.

Seek immediate medical care (call 911) for serious symptoms, such as difficulty breathing or swelling of the tongue. These symptoms can be a sign of a serious allergic reaction known as anaphylaxis, which can be life threatening if not treated immediately.

Seek prompt medical care if you are being treated for hives but mild symptoms recur or are persistent.

SYMPTOMS

What are the symptoms of hives?

Symptoms of hives include itching and swelling of the skin, causing raised red or skin-colored welts. The welts may come and go quickly and may resolve within hours or remain in some form for weeks. They can change rapidly in both size and number. Hives may have any shape, though they usually have well-defined borders. If you press on a hive, it will turn white (blanch), and then regain its reddish color when released.... Read more about hivessymptoms

CAUSES

What causes hives?

Hives are often triggered by an allergy. An allergy causes the release of histamines, which dilate the blood vessels in your skin, thus increasing blood flow to the area. The increased blood flow causes the redness and swelling that appear as a hive on your skin. Additionally, histamines cause the itching that is often associated with hives.... Read more about hivescauses

TREATMENTS

How are hives treated?

Although hives can be very uncomfortable, they generally respond to treatment. Antihistamines can block the action of the chemical mediators that are responsible for hives. Certain steroids may also be effective in reducing hives. Additionally, you can reduce the discomfort associated with hives by avoiding hot or cold water or tight-fitting clothing.... Read more about hivestreatments

Medical Reviewer: All content has been reviewed by board-certified physicians under the direction of Rich Klasco, M.D., FACEP. Last Annual Review Date: May 2, 2011 Copyright: © Copyright 2011 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Allergies and the Immune System