Hives (Urticaria) & Swelling (Angioedema)

These are common medical problems.  It is believed that about 20% of people experience these symptoms at least once in their lives.  Hives and swelling are considered to be different expressions of the same problem.

Hives occur mostly on the arms, legs and torso, while swelling occurs around the lips, eyes, hands feet and genitals and can involve the tongue and throat.

It is simply that the skin and mucous membranes in different areas swell in different ways.

How long the problem has been ongoing is also important.  Physicians call it “acute” if the problem is new or been present for 6 weeks or less and “chronic” if the problem has persisted longer.

Finding the cause of hives and swelling is difficult and about half of the time it is called “idiopathic”, meaning we can’t find a cause.  When the problem is acute generally few or no tests are needed.  The best clues to finding the cause come from the history such as starting a new medication, a bee sting or eating an unusual food.  When hives and swelling are chronic it is rare that any obvious causes can be found.  Furthermore, and contrary to what most people and some physicians believe, it is very rare for chronic hives and swelling to be caused by something external such as foods or inhaled things.  In most cases, skin testing to these materials is not done and if they are done and positive it simply identifies the person as being allergic, i.e. having hay fever, but are rarely the direct cause of the hives or swelling.

An autoimmune disease directed against the skin causes about 50% of chronic hives and swelling.  In other words the problem comes from “within”.  The test for this is the autologous serum skin test.  This means taking some blood, letting it clot and injecting a small amount of the serum under the skin.  If a local hive develops we consider this positive and an indication that the problem is autoimmune.  Recently a blood test has also been developed called the Chronic Urticaria Index (CU index) but some insurance plans may not cover this test; you should discuss these options with our physicians. Our physician may tell you that you need this customized test and not tests to foods or inhalants.  The outcome of this test may also be helpful in directing treatment, because immune suppressive medications may be necessary if antihistamines are not adequately controlling symptoms.  People with autoimmune urticaria, may also have other autoimmune diseases, most commonly thyroid diseases.  This condition is more common in women.  We may order blood tests to determine if this is a factor for you.