Hives
Hives, also known as urticaria, are raised, itchy welts on the skin that can vary in size from small spots to large areas. They occur when blood plasma leaks through small vessels in the skin due to the release of histamine from mast cells, often triggered by allergic reactions to foods, medications, or environmental factors. Approximately 20 percent of the population may experience hives at least once in their lifetime, with acute cases typically lasting a few days to weeks, whereas chronic hives persist for more than six weeks. Common triggers include insect bites, infections, and physical stimuli like pressure and temperature changes.
Treatment primarily focuses on identifying and eliminating the underlying cause, though antihistamines are often prescribed to alleviate symptoms. In severe cases, medications such as epinephrine or corticosteroids may be necessary. Research has highlighted that both allergic and non-allergic factors can contribute to hives, and ongoing studies continue to explore its complexities and effective treatments, especially in children. Overall, hives represent a common dermatological condition with multifaceted causes and treatment approaches.
Subject Terms
Hives
Also known as: Urticaria
Anatomy or system affected: Immune system, skin
Definition: Pink swellings, sometimes called wheals, that may occur in groups on any part of the skin
Causes and Symptoms
Hives are produced by blood plasma leaking through tiny gaps between the cells lining small vessels in the skin. A natural chemical called histamine is released from mast cells, which lie along the blood vessels in the skin. Allergic reactions, foods, drugs, or other chemicals can cause histamine release.
Hives can vary in size from as small as a pencil eraser to as large as a dinner plate, and they may join together to form larger swellings. When hives are forming, they are usually very itchy; they may also burn or sting. According to the American College of Allergy, Asthma, & Immunology, nearly 20 percent of the general population will have at least one episode of hives in their lifetime. Acute hives may last for a few days to weeks. If they last for more than six weeks, they are called chronic hives.
The most common causes of acute hives are foods, drugs, infections, insect bites, and internal diseases. Other causes include physical stimuli, such as pressure, cold, and sunlight.
Treatment and Therapy
The best treatment for hives is to find the cause and then eliminate it. Unfortunately, this is not always an easy task. Even if a cause cannot be found, antihistamines are usually prescribed to provide some relief. Antihistamines work best if taken on a regular schedule. It may be necessary to try more than one or use different combinations of antihistamines to find out what works best. In severe cases of hives, an injection of epinephrine (adrenalin) or a cortisone preparation can bring dramatic relief.
Perspective and Prospects
In 1927, Sir Thomas Lewis reported the association between wheals and small blood vessel dilation, which later confirmed the importance of histamine as a cause of hives. Years of research showed that in addition to allergy, nonimmunological stimuli can cause hives as well. According to an October 2014 PLoS One article by Mey-Fann Lee et al., 30 to 50 percent of patients with idiopathic chronic hives have autoantibodies in their systems, suggesting that the causes of hives could be multifactorial. The study of hives continued into the twenty-first century as researchers attempted to learn more about the condition and its treatments. Clinical trials at prestigious medical centers such as the Mayo Clinic in Minnesota focused on understanding the condition in children and adults.
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