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Understanding Hives (Urticaria)

Urticaria (hives) are red, itchy, and swollen areas on the skin. They are most often an allergic reaction from eating a food or taking a medicine. Sometimes the cause may be unknown. A single hive can vary in size from a half inch to several inches. Hives can appear all over the body. Or they may appear on only one part of the body.

Causes of Hives

Hives can be caused by food and beverages such as:

  • Nuts

  • Peanuts

  • Eggs

  • Shellfish

  • Milk

Hives can also be caused by medicines such as:

  • Antibiotics, especially penicillin and sulfa-based medicines 

  • Anticonvulsant or antiseizure medicines 

  • Chemotherapy medicines 

Other causes of hives include:

  • Infection or virus

  • Heat

  • Cold air or cold water

  • Exercise

  • Scratching or rubbing your skin, or wearing tight-fitting clothes that rub your skin

  • Being exposed to sunlight or light from a light bulb, in rare cases

In some cases, hives may occur again and again with no specific cause.

If you have hives

  • Avoid the food, drink, medicine, or other factor that may be causing the hives.

  • Make a thick paste of baking soda and water. Apply the paste directly to your skin. This can help lessen itching.

  • Talk with your healthcare provider right away if you think a medicine gave you hives.

Watch for anaphalaxis

If you have hives, watch for symptoms of a severe reaction that affects your entire body. This is called anaphylaxis. Symptoms can include swollen areas of the body, wheezing, trouble breathing or swallowing, and a hoarse voice. This reaction may happen right away. Or it may happen in an hour or more. In extreme cases, the airways from mouth to lungs may swell and prevent breathing. This is a medical emergency. Use epinephrine medicine if you have it, and call 911 or go to the emergency room.


When to call your healthcare provider

Call your healthcare provider if:

  • Your hives feel uncomfortable

  • You have never had hives before

When to call 911

Call 911 right away if you have:

  • Swelling in your lips, tongue, or throat, called angioedema

  • Trouble breathing or swallowing

© 2000-2017 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.