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Hives

(Angioedema; Urticaria)

Definition

Hives are small, itchy, red swollen areas on the skin. The swelling occurs singularly or in clusters. Hives tend to fade after a few hours, but new ones can appear. Most cases go away within a few days. However, some last a few weeks or longer.
Hives
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Causes

Hives are often caused when the body releases a chemical called histamine. Histamine is released during an allergic reaction. Many people, though, get hives without being exposed to something they are allergic to.
While the cause is unknown in some cases, these factors may cause hives:

Risk Factors

Factors that may increase your risk of hives include:

Symptoms

Symptoms of hives can vary from mild-to-severe:

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. You may need to see a doctor who specializes in skin disorders (dermatologist) or allergies (allergist).
Your bodily fluids and tissues may be tested. This can be done with:
Images may be taken of your bodily structures. This can be done with x-rays.

Treatment

The best way to treat hives is to find and then avoid the cause.
If the cause can't be found, there are medications to reduce symptoms or treat hives:

Prevention

The best way to prevent hives is to avoid the allergen that caused you to get hives in the past.

RESOURCES

American Academy of Allergy, Asthma, and Immunology http://www.aaaai.org

American Academy of Dermatology http://www.aad.org

CANADIAN RESOURCES

Canadian Dermatology Association http://www.dermatology.ca

Health Canada http://www.hc-sc.gc.ca

References

Dibbern DA Jr. Urticaria: selected highlights and recent advances. Med Clin North Am. 2006;90:187-209. Review.

Gambichler T, Breuckmann F, Boms S, Altmeyer P, Kreuter A. Narrowband UVB phototherapy in skin conditions beyond psoriasis. J Am Acad Dermatol. 2005;52:660-670. Review.

Guldbakke KK, Khachemoune A. Etiology, classification, and treatment of urticaria. Cutis. 2007;79:41-49. Review.

Hives. American Academy of Dermatology website. Available at: http://www.aad.org/dermatology-a-to-z/diseases-and-treatments/e---h/hives. Accessed September 22, 2015.

Kaplan Allen P.Chronic urticaria: pathogenesis and treatment. J Allergy Clin Immunol. 2004; 114(3): 465-474.

Tips to remember: allergic skin conditions. American Academy of Allergy, Asthma, and Immunology website. Available at: http://www.aaaai.org/patients/publicedmat/tips/allergicskinconditions.stm. Accessed September 22, 2015.

Urticaria. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 1, 2015. Accessed September 22, 2015.

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