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Allergies Health Center

Understanding Hives -- the Basics

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What Are Hives?

Hives -- what your doctor calls ''urticaria'' -- can be caused by allergic or other types of reactions. Hives appear as lesions on your skin. They’re usually very itchy and can last just a few minutes or several days before going away. Occasionally, however, these annoying blotches can be a sign of more serious problems, especially when someone has symptoms like trouble breathing.

Another reaction that sometimes happens along with hives is called angioedema. It’s swelling that develops under the skin. With angioedema, you may have deep swelling in such places as around the eyes and lips, and sometimes the genitals, hands, and feet. 

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In rare cases, the swelling from angioedema happens in the throat and causes trouble breathing. If that happens, you should call 911.

If you have hives along with fever, nausea, stomach cramps, shortness of breath, and a drop in blood pressure after a bee sting, insect bite, or drug injection, that can be a sign of a life-threatening allergy. Carry two epinephrine shots (such as Auvi-Q or Epi-Pen) if your doctor has prescribed them and use them if needed. Then call 911 or go to the hospital.

What Causes Hives?

Hives happen when some cells in the skin release a substance called histamine that triggers allergy symptoms.

Common triggers for hives include:

  • Foods like milk, fish, or nuts
  • Drugs like aspirin or penicillin
  • Food additives like flavorings and preservatives
  • Bug bites
  • Extreme cold or heat
  • Pressure on the skin
  • Viral infections

How Do You Treat Hives?

The best treatment is to figure out what’s causing them and stay away from it. Antihistamines can reduce your symptoms.

If over-the-counter antihistamines don’t help or your hives seem to be lingering, see your doctor. He or she may prescribe steroid pills or prescription antihistamines.

At home, try these tips:

  • Apply cool compresses or wet cloths to the hives.
  • Try to work and sleep in a cool room.
  • Wear loose-fitting, lightweight clothes.

WebMD Medical Reference

Reviewed by Luqman Seidu, MD on March 24, 2014

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