You’d think itching all over, as your body is transformed by welts, would be enough torture for one person. But apparently not, since 40-50 percent of people who suffer from urticaria (hives) also have angioedema (swelling). You might be wondering, “What’s the difference between these two types of skin eruptions.”
Urticaria, the technical term for hives, is an elevation of well-defined portions of the skin which may be small (millimeters in diameter, width or length) or large (several centimeters), sparse in number, or of a sudden onset. You can easily determine where the welted skin begins and ends. Sometimes the elevated portion of skin is lighter in color compared to the rest of surrounding area. There may be a halo of reddened skin surrounding the elevated segment.
Urticarial eruptions are almost always intensely itchy. The number, size, and shape of the hives typically change over the course of the day. Hives can be round, linear, or irregularly shaped. Sadly, many people experience the full repertoire of sizes and shapes when they have a flare-up. It can be extremely embarrassing when hives erupt on exposed areas of skin, such as the face, forearms or hands.
In contrast, angioedema is represented by a deeper swelling of the skin which has no distinguishable borders. Often an entire region of the body is involved, without any discoloration of the overlying skin.** The dreadful cosmetic distortion caused by this type of invasive swelling is unimaginable until you’ve experienced it.** The entire side of the face may swell up to more than three times its size, making it appear as if you’ve been through twelve rounds of boxing. The eyelid may swell completely shut, or the hand may take on the appearance of a baseball glove. The tongue can swell and protrude to the point that closing the mouth, for a while, may be impossible.
Angioedema doesn’t tend to cause itching, but many people experience numbness or tingling sensation in the areas of the body involved. Sometimes a burning sensation accompanies the swelling, especially when there is pressure on the swollen area. It’s difficult to walk when angioedema occurs on the bottom of the feet or ankles because of the burning pain. Both urticaria and angioedema are forms of tissue swelling caused by similar mechanisms.
What Causes Hives and Swelling?
Many, but not all bouts of hives and swelling are caused by the release of histamine. Histamine is a substance released from cells referred to as mast cells. Mast cells underlie the skin and other body organs which interface in some way with the outside world (nose, eyes, throat, stomach, lungs). Mast cells store histamine and release it when stimulated to do so by an allergen or another trigger.
Once released, the histamine may stimulate nerve endings in the surrounding tissue, and cause itching. Also, nearby blood vessels may respond to histamine by dilating and becoming leaky (which causes reddening and swelling of the skin). Urticarial eruptions occur when this happens in upper layers of skin, close to the surface. When the above chain of events occurs in deep layers of skin, angioedema occurs.
So imagine hives and swelling occurring simultaneously for hours or days, and involving multiple areas of the body. Such an experience is extremely distressing, and can be life threatening if associated with throat or tongue swelling, difficulty breathing, or lightheadedness. When the above combination of symptoms and signs occur, anaphylaxis is the diagnosis.** Anaphylaxis** is potentially life-threatening and requires immediate medical attention when it occurs. This diagnosis should be considered whenever two or more systems of the body are under attack by an allergic reaction (skin, gastrointestinal tract, respiratory system or cardiovascular system).
Although most people who have urticaria and angioedema don’t require hospitalization, many appropriately seek help from emergency departments.
Treatmenntihistamines are a cornerstone in the treatment of urticaria and angioedema. These medications block histamine at the level of nerve endings and blood vessels, preventing itching and swelling. Of course, if it were this simple, seeing a doctor wouldn’t be necessary, because there are plenty of over-the-counter antihistamines available for purchase. Unfortunately, by the time the diagnosis is realized, the hives and swelling are often far too advanced to be completely relieved by histamine blockers. Your doctor may select additional medications, to use on a short-term basis, to reduce and suppress hives and swelling.
Fortunately most people respond to treatment and avoidance measures after a full evaluation. Knowing how to prepare for the first doctor’s appointment is crucial. Prevention of future flare-ups becomes the primary goal once treatment begins.
References and Additional Articles:
Board Certified Allergist and Asthma Specialist