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Overview of Hives
The medical term for hives is “urticaria”. Hives that occur deeper under the skin can cause swelling of the throat, lips, or other areas. This is called “angioedema.”
Hives are a common and very uncomfortable problem. About 15-20% of people will have an episode of hives at some point in their life.
Hives that have lasted less than 6 weeks are called “acute” (meaning short-term). Hives that have been present longer than 6 weeks are called “chronic.” It is sometimes easier to identify a cause for hives that started recently than for hives that have been going on for many months or years.
Causes of Hives
Possible causes for acute (recent or short-term) hives include:
• Food allergies (shrimp, peanuts, etc.)
• Drugs (especially antibiotics, but other medicines can be involved)
• Bee stings
• Pollen or dander (animal) allergy
It is possible to develop an allergy or intolerance to a food, shampoo, lotion, detergent, etc. even when you’ve been using it without trouble for a long time.
Possible causes for chronic (ongoing or long-term) hives include the things listed above, plus:
• Latex or other contact irritants such as perfume or dye in products
• Cold; heat (i.e. hot showers or hot tubs); vibration; pressure (i.e. tight waistbands); and other physical stimuli
• Systemic illnesses such as thyroid imbalance, hepatitis, Lyme disease, parasitic infections, malignancy, etc.
• “Auto-immune” reactions—that is, the body has an allergic reaction to its own cells.
In many cases, no cause for the hives can be identified despite extensive testing. Hives without an identifiable cause are called “idiopathic” hives. Up to 90% of chronic hives are idiopathic.
Testing for Causes of Hives
A variety of tests are used to try to find a cause for hives. These include:
1) Environmental percutaneous tests. These check for allergies to natural substances such as pollen, dust, mold, and dander.
2) Food percutaneous tests. These check for food allergies. They sometimes give “false positives” so they need to be double-checked by doing a food-avoidance trial. If this doesn’t make a difference in 1-2 weeks, you can probably continue eating that food.
3) Chemical patch tests. These check for allergic reactions to a variety of manmade things such as nickel, preservatives, fragrances, chemicals used to prepare leather, chemicals in hair dye, etc.
4) Blood tests. Occasionally hives are caused by other illnesses such as thyroid imbalance, hepatitis, Lyme disease, parasitic infections, etc. We can check for these with lab tests.
5) Food patch tests. This is another approach to food allergy testing. Samples of the food are mixed with a thickener and placed on the surface of the skin, covered with a protective layer. After 48 hours we remove the tests and read the results. These can show positive even when food percutaneous tests did not.
1) Oral allergy medicines are the mainstay of treating hives. Topical creams and lotions may feel comforting but they don’t address the internal allergic reaction causing the hives.
2) Prednisone can be helpful to get rid of hives short-term, but it has many side effects and tends to cause a “rebound” effect (i.e., hives are worse when you stop prednisone than they were before). We use this cautiously.
3) Avoid known irritants as much as possible.
4) Loose-fitting, cotton clothing is often less irritating than wool or synthetic blends. Avoid scratching as much as possible. Take warm (not hot) baths or showers. Heat and sweating (such as hot tubs, gym workouts, etc.) can worsen hives. Don’t use dryer sheets.
5) Stress exacerbates hives for many people. Enough sleep, healthy foods, gentle exercise, counseling, and relaxing activities may help.
6) Use SPF 15 or higher sunscreen on a regular basis. Avoid getting sunburned.
7) There are no known long-term health consequences from hives. However, they may cause anxiety and depression. If you have trouble with these, please talk to a counselor.