Definition of Urticaria

UrticariaUrticaria is the clinical term for hives, an outbreak of wheals on the skin’s surface. Acute urticaria, which comes on suddenly, typically signals a hypersensitivity reaction.

The wheals contain fluid the immune response draws from the cells of the skin. They itch, often intensely (pruritus), and may appear and recede in various locations on the body.

Breathing difficulties with urticaria may indicate anaphylaxis, a life-threatening hypersensitivity reaction causing swelling of the airways that requires emergency medical care.


When urticaria manifests, the first focus is on subduing the response to relieve the symptoms and prevent complications. The doctor may administer an epinephrine injection to thwart a hypersensitivity response that appears to be intensifying or if the urticaria progresses.

Most urticaria responds fairly quickly to antihistamine medications such as diphenhydramine (Benadryl) or hydroxyzine (Vistaril), which the doctor can administer by injection for severe urticaria.

The wheals generally retreat within 6 to 8 hours and are entirely gone in about 36 hours with antihistamine therapy. Most people recover fully and can avoid future episodes by avoiding exposure to the substance that caused the reaction.


Potential complications associated with urticaria are uncommon though can be life-threatening. Angioedema occurs when fluid accumulates in tissues other than the skin; most doctors consider it a progressive form of urticaria. Angioedema can affect internal structures, causing pressure and swelling that affects the ability of vital organs to function.

When angioedema affects the airways it can cause breathing difficulties and anaphylaxis, the most serious hypersensitivity reaction. These complications occur only with repeat exposure to the substance causing the reaction.


Urticaria represents an immune response in which the immune system releases immunoglobuline (IgE), which causes mast cells to release histamine. The histamine draws fluid into the tissues. Numerous drugs, foods, environmental factors such as pollen and animal dander, and health conditions may cause urticaria.

It is important to attempt to identify the causative factor to prevent recurrences. Hypersensitivity responses, which people also call allergic reactions, tend to intensify with repeated exposure to the substance.

A similar release of IgE occurs with chronic urticaria, as an immune-mediated response related to serious illnesses that challenge the immune system such as cancer. Autoimmune disorders that affect the connective tissue, such as systemic lupus erythematosus (SLE), amyloidosis, and rheumatoid arthritis, can also cause chronic urticaria, as can exposure to extreme heat or cold. As with acute urticaria, treatment for chronic urticaria first targets symptom relief.


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