MEDICAL CONDITIONS
Hives (Urticaria)
&
Angioedema
What are hives (urticaria)?
"Hives" and "welts" are red, itchy, and raised areas of the skin of varying shapes and sizes. Medically, hives are also known as urticaria. Hives are the result of histamine and other compounds that are released from cells called mast cells. Histamine causes serum to leak from the local blood vessels, which causes swelling in the skin. Hives can occur anywhere on the body, but are most commonly found on the trunk. Hives tend to erupt in clusters. Clusters of hives typically fade away and clear up within 2-48 hours as new clusters appear on other areas of the skin.
Urticaria is a common skin condition that will affect one out of every five persons in the population. The cause of urticaria is often unknown. Fortunately, urticaria usually resolves by itself, and is rarely life-threatening.
What are the categories of urticaria?
Urticaria can be divided into three categories: acute, chronic, and physical.
Acute Urticaria
Acute urticaria is the most common of the three categories. In patients with acute urticaria, hive eruptions (a single eruption or a few eruptions) usually resolve within six (6) weeks. Patients with acute urticaria tend to be young and have a history of allergies. Patients with acute urticaria can often relate their eruptions to exposure to certain foods, medications, or virus infections. Management of acute urticaria involves treating the symptoms of itching. Extensive allergy testing is usually not warranted.
Chronic Urticaria
Chronic urticaria is less common than acute urticaria. In patients with chronic urticaria, hives can last from months to years. Forty percent of patients with chronic urticaria lasting longer than 6 months can expect to continue suffering from this condition 10 years later. While chronic urticaria can affect anybody, it most commonly affects women between the ages of 40-65 years. The cause of chronic urticaria is usually not known; only 10 percent of the cases can be attributed to a specific cause. Even when the cause is known, treatment is usually not satisfactory. Chronic urticaria can effect other internal organs (such as the lungs, muscles and gastrointestinal tract), and can cause symptoms of muscle soreness, shortness of breath, vomiting, and diarrhea .
Physical Urticaria
Physical urticaria refers to hives that occur as a result of direct physical stimulation of the skin. Physical stimuli can be cold, heat, sun exposure, vibration, pressure, sweating, exercise and many others. In patients with physical urticaria, the hives usually occur at the site of direct stimulation, but can also rarely appear on other skin areas. Most of the hives appear within one hour of the stimulation, but on rare occasions can appear hours later.
What is angioedema?
Angioedema is a form of tissue swelling similar to urticaria, but involving deeper skin tissues (i.e. "deep hives" ) and generally lasting longer than urticaria. Hives and angioedema can appear together or separately on the body. Patients with angioedema most commonly develop swelling around eyes, lips hands and/or feet. Occasionally, severe, prolonged tissue swelling can be disfiguring. Rarely, angioedema of the throat, tongue or the lungs can obstruct airway, impede breathing, and become life threatening.
How do urticaria and angioedema develop?
Urticaria and angioedema represent skin and tissue reaction to chemicals released by specialized cells called mast cells. Mast cells are histamine-containing cells found in the skin and many other tissues. For unknown reasons, mast cells can become brittle and rupture, releasing stored chemicals, such as histamines and other chemicals that can cause tissue swelling. Foods, medications, physical stimuli, infections, and certain illness can cause the mast cells to release these chemicals.
What are known causes of urticaria and angioedema?
In most patients, the causes of urticaria and angioedema are unknown. Less than 10% of the patients can relate their symptoms to exposure to certain medications, foods or food additives, infections, physical stimuli, concurrent illnesses, or immune-related disorders. - "Hives" or "welts" are medically known as urticaria.
- There are many forms and causes of hives. Most often, the cause of hives is unknown.
- Angioedema is similar to hives, but affects a deeper skin layer.
- Treatment is directed toward relief of symptoms, typically involves antihistamines, and depends on whether an underlying cause is determined.
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