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Hives


Alternative Names:

Urticaria

Causes, incidence, and risk factors:

When you have an allergic reaction to a substance, your body releases histamine and other chemicals into the blood. This causes itching, swelling, and other symptoms. Hives are a common reaction. Persons with other allergies, such as hay fever, often get hives.

When swelling or welts occur around the face, especially the lips and eyes, it is called angioedema. Swelling can also occur around your hands, feet, and throat.

Many substances can trigger hives, including:

  • Animal dander (especially cats)
  • Insect bites
  • Medicines
  • Pollen
  • Shellfish, fish, nuts, eggs, milk, and other foods

Hives may also develop as a result of:

Treatment:

Treatment may not be needed if the hives are mild. They may disappear on their own. To reduce itching and swelling:

  • Do not take hot baths or showers.
  • Do not wear tight-fitting clothing, which can irritate the area.
  • Your health care provider may suggest that you take an antihistamine such as diphenhydramine (Benadryl). Follow your provider's instructions or package instructions about how to take the medicine.

If your reaction is severe, especially if the swelling involves your throat, you may require an emergency shot of epinephrine (adrenaline) or a steroid. Hives in the throat can block your airway, making it difficult to breathe.

Expectations (prognosis):

Hives may be uncomfortable, but they are usually harmless and disappear on their own. In most cases, the exact cause of hives cannot be identified.

Complications:
  • Anaphylaxis (a life-threatening, whole-body allergic reaction that causes breathing difficulty)
  • Swelling in the throat can lead to life-threatening airway blockage
Calling your health care provider:

Call 911 or your local emergency number if you have:

  • Fainting
  • Shortness of breath
  • Tightness in your throat
  • Tongue or face swelling
  • Wheezing

Call your health care provider if the hives are severe, uncomfortable, and do not respond to self-care measures.

Prevention:
  • Avoid exposure to substances that give you allergic reactions.
  • Do not wear tight-fitting clothing and do not take hot baths or showers just after having hives. These can cause hives to return.
References:

Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Philadelphia, Pa.: Elsevier Mosby; 2009:chap 9.


Review Date: 5/15/2013
Reviewed By: Kevin Berman, MD, PhD, Associate, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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