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 centres.
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 0.6 cm (0.25 in.) to 7.6 cm (3 in.) 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: February 20, 2015
Author: Healthwise Staff
Medical Review: William H. Blahd, Jr., MD, FACEP - Emergency Medicine & H. Michael O'Connor, MD - Emergency Medicine
Public Health Alerts
Public health alerts include information about outbreaks, advisories and product recalls. Click on the links below to read the most recent alerts, or visit our Public Health Alerts web page.
Want More Information?
HealthLink BC, your provincial health line, is as close as your phone or the web any time of the day or night, every day of the year.
Call 8-1-1 toll-free in B.C. or for deaf and hearing-impaired, call 7-1-1.
You can speak with a health service representative, who can also connect you with a:
- registered nurse any time, every day of the year;
- registered dietitian from 9am to 5pm, Monday to Friday;
- pharmacist from 5pm to 9am, every day of the year.
Translation services are available in more than 130 languages.
FIND Services and Resources
If you are looking for health services in your community, you can use our directory to FIND hospitals, clinics, and other resources.
To learn more about Healthwise, visit Healthwise.org
© 1995-2015 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
Is it an emergency?
If you or someone in your care has chest pains, difficulty breathing, or severe bleeding, it could be life-threatening. Call 9-1-1 or the local emergency number immediately. If you are concerned about a possible poisoning or exposure to a toxic substance, call Poison Control now at 1-800-567-8911.