Hives (Urticaria), Acute Hives & Chronic Hives

Definition: Hives is the common name for urticaria, a skin condition that is often characterized by pink or red welts or bumps that itch and may burn or sting. Hives (urticaria) is often classified as either: Acute Hives (acute urticaria) or Chronic Hives (idiopathic urticaria). Acute hives are often caused by an allergic reaction to a substance and last less then 6 weeks. Chronic hives last more than 6 weeks and is more complex to diagnose and treat.

Acute Hives

Causes: Acute Hives often results as an allergic reaction to foods, food additives, medications, insect bites, and infections. When a person has an allergic reaction to a substance (inhaled, injected, or ingested), histamine and other chemicals are released into the bloodstream which in turn causes dilation of capillaries allowing fluid to leak out into the epidermis (outer skin layer). This action results in the symptoms outlined below.

Common foods that cause acute hives include: milk, shellfish, berries and nuts. Medications that cause acute hives are most commonly antibiotics like doxycylin. Other causes of acute hives include pollen and animal dander.

Symptoms: Acute hives often appear as white, pink, red or flesh colored bumps or welts in round or oval shapes often itch. They can vary in size from a few millimeters (similar to a mosquito bite) or as large as a dinner plate.

"The welts may enlarge, spread, and join together to form larger areas of flat, raised skin. They can also change shape, disappear, and reappear within minutes or hours. The welts tend to start suddenly and resolve quickly. When you press the center of a red welt, it blanches (turns white)." (1)

"Hives also might look like rings or groups of rings joined together. Hives can appear in clusters and might change locations in a matter of hours." (2)

Continued exposure to the allergen causing hives will result in further outbreaks and lesions.

Hives can occur on any part of the skin surface but are most common on the arms and legs. Acute hives can last hours, days and up to six weeks.

Acute hives is easier to diagnose and treat then chronic hives.

Chronic Hives: The exact causes of chronic hives (idiopathic urticaria) are not clear and do not resolve quickly. A diagnosis of chronic hives is made when they appear more than twice a week and last longer than six weeks. Causes of chronic hives include:

Immune system releases histamines (50 percent of cases)
Thyroid disease
Hormonal problems
Infections (including sinus infections)
Yeast infection
Unknown

Chronic hives can be hard to eradicate. "In one study, 75% of people with chronic hives have symptoms for longer than 1 year, 50% have symptoms for longer than 5 years, and 20% have symptoms for decades. In 50% of the cases, the offending agent is not identified." (3)

Physical hives, or physical urticaria, is a subset of chronic urticaria. This means that a specific type of physical stimulus is present in certain people. There are many types of physical urticaria which depend on their cause: sun, heat, cold, water and pressure on the skin.

In less often but severe cases, physical hives can affect the throat or larynx and cause difficulty breathing.

An accurate diagnosis of chronic hives or physical hives should be made by a doctor that specializes in allergies and immunology. [Locate an allergist-immunologists nearest you].

"If hives are an early sign of a whole-body reaction, other symptoms to look for include swelling of the tongue, lips or face; wheezing; dizziness; chest tightness; and breathing difficulties. If these symptoms occur, get immediate medical attention. You could be developing anaphylaxis, a life-threatening condition." (4)

Treatment: Acute hives will eventually disappear on their own if contact with the cause or allergen is avoided. The irritating scratching or itching often associated with hives can be relieved with calamine lotion. Over the counter antihistamines (such as Benadryl, Zyrtec, Claritin, Allegra) taken regularly can prevent the release of histamines which cause the welts or bumps on the skin.

Oral or injectable steroids are administered in cases when the hives do not respond to antihistamines. In severe cases of chronic hives, Epinephrine is prescribed. Epinephrine is a very powerful blocker of histamines and works quickly, although it's duration in the body is for a short period.

See your doctor if you believe you have chronic hives, physical hives or acute hives that won't respond to antihistamines and prevention of allergens.

Sources:
(1) MedlinePlus Encyclopedia, Hives, July 2005
(2) KidsHealth.org, Help With Hives, August 2004
(3) dermatology.about.com, All About Hives, Heather Brannon, MD, March 2006
(4) InteliHealth, Hives (Urticaria), March 2005asdfdsafsda

Conditions & Diseases: Skin Diseases

Hives (Urticaria)