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Hives

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(Angioedema; Urticaria)

Definition

Hives are small, itchy, red swellings 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

A risk factor is something that increases your chance of getting hives. Tell your doctor if you have any of these:
  • Exposure to an allergen (something that causes an allergic reaction)
  • Exposure to an allergen that triggered hives in the past

Symptoms

Symptoms of hives can vary from mild-to-severe:
  • Itchiness
  • Redness
  • Swelling
  • Excessive swelling of the eyelids, lips, or genitals
  • Burning
  • Stinging
  • Difficulty breathing or swallowing— Call 911 if you are having these symptoms.

Diagnosis

The doctor will ask about your symptoms and medical history, and do a physical exam. You may need to see a doctor who specializes in skin disorders (dermatologist) or allergies (allergist). The following tests will be done:
  • Skin prick test —a tiny bit of an allergen is placed in your skin with a needle to see if the area becomes raised or irritated
  • Skin biopsy —a small portion of abnormal skin is removed
  • X-ray —a test that uses radiation to take a picture of structures inside the body, especially bones
  • Blood tests

Treatment

The best way to treat hives is to find and then avoid the cause.
If the cause can't be found, there are medicines to reduce symptoms or treat hives:
  • H1-blocking medicines like:
    • Diphenhydramine (eg, Aler-Cap, Benadryl Allergy)
    • Hydroxyzine (eg, Vistaril)
    • Cyproheptadine
    • Fexofenadine (eg, Allegra)
    • Loratadine (eg, Claritin)
    • Acrivastine (eg, Semprex)
    • Cetirizine (eg, Zyrtec)
    • Doxepin (eg, Prudoxin, Sinequan, Zonalon)
    • Levocetirizine (eg, Xyzal)
  • H2 blocking medicines like:
    • Cimetidine (eg, Tagamet HB)
    • Ranitidine (eg, Zantac)
    • Famotidine (eg, Pepcid)
  • Leukotriene antagonists like Montelukast
  • Oral steroid medications (eg, prednisone ) for hives resistant to other treatments
  • Anti-inflammatory medicines
  • Immunosuppressant medicines
  • Ultraviolet light therapy
  • Prescription epinephrine (adrenalin) injections for cases when swelling affects the airways

Prevention

The best way to prevent hives is to avoid 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/

Dermatologists.ca http://www.dermatologists.ca/

References

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

DynaMed Editors. Urticaria/angioedema. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated June 2008. Accessed July 7, 2008.

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.

Habif TP. Clinical Dermatology. 4th ed. St. Louis, MO: Mosby; 2004.

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

National Institute of Arthritis and Musculoskeletal and Skin Diseases website. Available at: http://www.niams.nih.gov/ .

Skin biopsy. EBSCO Health Library website. Available at: http://www.ebscohost.com/healthLibrary/ . Updated October 2007. Accessed June 17, 2008.

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 July 7, 2008.

Urticaria—hives. American Academy of Dermatology website. Available at: http://www.aad.org/public/publications/pamphlets/skin%5Furticaria.html . Updated June 2008. Accessed July 7, 2008.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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