Hives and Angioedema Overview

Hives is an allergic skin reaction that comes on suddenly. The hives themselves are slightly raised, smooth, flat-topped bumps called wheals (look like mosquito bites) and welts that are usually more red in color than the surrounding skin and cause severe itching.
Angioedema is like hives, only the welts are larger and form at a deeper layer in the skin. This causes severe swelling, usually in the face, near the eyes and mouth.

Hives occur when the body's capillaries and tiny veins get leaky. Fluid escaping from some of these blood vessels gets trapped in parts of the skin and lining membranes of the body, causing the localized swelling in the hives. This leakiness can be caused by classic allergic reactions in which histamine triggers an inflammatory response. It can also be caused by a number of other regulatory systems in the body in response to different types of triggers.

The Facts on Hives
Hives, called urticaria by doctors, is one of the most common causes of skin inflammation. Up to 20% of the population will suffer from urticaria at least once in their lives. Large, itchy red rashes called hives rise up and die away quickly, sometimes to be replaced by others. A few people find that the condition often

Symptoms of ordinary hives
Ordinary hives flare up suddenly and usually for no specific reason. Welts appear, often in several places. They flare, itch, swell, and go away in a matter of minutes to hours, only to appear elsewhere. This sequence may go on from days to weeks. Most episodes of hives last less than six weeks. Although that cutoff point is arbitrary, hives that last more than six weeks are often called "chronic."

How common are hives?
Approximately 1 in 6 people will develop hives some time during their life and are most common in children. They eventually disappear in most people. They may reappear following infection, when under stress or for no particular reason.
Hives occur in the skin
Underneath the lining of the skin, gut, lungs, nose and eyes are mast cells. These are designed to kill worms and parasites. Mast cells are like "land-mines", and contain "bags" filled with irritant chemicals including histamine

common triggers that cause hives
The most common skin allergy triggers that cause hives include:
• Medication such as antibiotics, codeine, penicillin, sulfa, anticonvulsant drugs, phenobarbital, and aspirin
• Foods like shellfish, nuts, tomatoes, soy, chocolate, and berries
• Pollen
• Cat dander
• Insect bites such as bee ans wasp stings

Emergency situations
For a severe attack of hives or angioedema, you may need an emergency injection of adrenaline (epinephrine) and a trip to the emergency room. If you have repeated attacks, despite treatment, your doctor may prescribe — and instruct you how to use — adrenaline to carry with you for use in emergency situations.
Treatment
Usually, if hives appear suddenly, they subside without any treatment within days and sometimes within minutes. If the cause is not obvious, the person should stop taking all nonessential drugs until the hives subside.