What are Hives?
Hives are welt-like skin rashes that can be as small as a pea and as large and flat as a pancake. Hives can be a true allergic reaction to foods, medications (antibiotics, anti-inflamatories), insect stings, cosmetics, pet dander or dust mites. They can itch or burn, and be a mild annoyance or cause life-threating symptoms if they develop in the throat. Urticaria (hives) is common, affecting 10% to 20% of people at some point in their lives. Half of those affected continue to have symptoms for more than 6 months after the initial outbreak.
What Causes Hives?
Hives develop in response to histamine, when blood plasma leaks out of small blood vessels in the skin. Histamine is a chemical released from specialized cells along the skin’s blood vessels that triggers an inflammatory response.
An outbreak of hives can usually be easily treated with antihistamines (Claritin, Allegra, Zyrtec), but the challenge is to find out why they are occurring, so you don’t keep getting them.
How we test for Hives
- First, I take a detailed history to try to link your hives to recent exposures, most commonly foods and medications. But hives can be caused by cold weather, the sun (solar urticaria), vibrational devices, exercise, excessive sweating (cholinergic), contact with objects, and exposure to cats, dogs, mold, or dust mites. Hives can be also due to an autoimmune process related to the thyroid.
- Next, I’ll do allergy blood testing with ImmunoCAP or the newer test called the ISAC test, which analyzes the different protein components in the allergens. If I suspect a contact allergy I’d do a patch test. I might also do a general blood count test, liver function test, and thyroid antibodies.
- The best way to eliminate hives is to avoid the possible trigger. The medical treatment includes using second generation antihistamines (Claritin, Allegra, Zyrtec), which are generally not sedating. There are times in more difficult cases where an H2 blocker is added (Zantac) to help control histamine release from the skin. Note, typically cortisone creams are not effective for hives because the rashes are not localized. Occasionally, oral cortisone is needed to control a severe outbreak.
For more information or to get tested, contact us.