Hives (Urticaria)

The medical name for hives is urticaria. Hives are a common sign of an allergic reaction. Hives can also occur due to other causes, including a viral infection. 

Hives are raised bumps, called welts or wheals, on the skin. Hives can be small or large and can occur anywhere on the body. Hives are itchy. Hives can occur due to an acute allergic reaction to an allergen. Hives can be one sign of an allergic reaction or hives can be one of many signs of an allergic reaction. Hives can occur during severe allergic reactions known as anaphylaxis  (anna-fih-LACK-sis).

Call your health care provider if:

  • Your hives are making you uncomfortable
  • You have never experienced hives before

Go to the emergency room or call 911 if:

  • Your hives are severe and cover a large area of your body
  • You have other symptoms such as difficulty breathing

Your doctor will look at your skin and will ask you about your recent medical history. The doctor may do allergy testing.

Hives can occur due to unknown causes. We call these types of hives idiopathic urticaria. Idiopathic means “unknown cause.” Hives can also be chronic. When you have chronic hives for an unknown reason, your doctor may diagnose you with Chronic Idiopathic Urticaria, or CIU.


Medical Review October 2015.