Skip to Content
Home > Health Information > Health Library > Hives
Hives (urticaria) are an allergic reaction of the skin that may last a few minutes or can persist for a few days. They appear as raised, red, itchy bumps (wheals) of different shapes and sizes, with defined red margins and pale centers.
Hives may appear and then disappear at random and seem to move from place to place on the skin. Hives may range in size from less than 0.25 in. (0.6 cm) to 3 in. (7.6 cm) across or larger. Patches of hives may combine to form raised, reddened skin over large areas of the body.
Hives may appear as a reaction to a medication, food, or infection. A single area of swelling often occurs after an insect bite at the site of the bite. Other possible causes include contact with plants, things you breathe in (inhalants), stress, makeup, and exposure to heat, cold, or sunlight. Often a cause cannot be found.
Hives are often minor, but they can also be the first sign of a life-threatening allergic reaction (anaphylaxis) that requires emergency care.
Current as of:
April 7, 2019
Medical Review:William H. Blahd, Jr., MD, FACEP - Emergency Medicine & Adam Husney, MD - Family Medicine & Martin J. Gabica, MD - Family Medicine & H. Michael O'Connor, MD, MMEd, FRCPC - Emergency Medicine
To learn more about Healthwise, visit Healthwise.org.
© 1995-2019 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.
See important information from Billings Clinic on Non-discrimination and Interpreter Services.
Billings Clinic is proud to be an equal opportunity/affirmative action (EOE/AA) e-verify employer.