Urticaria is the medical term for hives. Hives are pink welts or swellings that can itch, burn or sting. Hives can vary in size from as small as a pen tip to as large as a dinner plate, and they may join together to form even larger swellings.
Hives generally go away within 24 hours, although new hives may appear as old ones fade. If you experience hives that last longer than 24 hours, see a board-certified dermatologist for evaluation.
Hives can appear on any part of the skin. Swelling tends to be greater when hives form around the eyes, lips or genitals. Although it can be frightening, the swelling usually goes away in less than 24 hours.
In rare cases, severe swelling may block your airway. If you have hives and experience difficulty breathing or swallowing, seek immediate emergency care.
What Causes Hives?
Anyone can get hives. Approximately 10 to 20 percent of the population experience at least one episode of hives in their lifetime.
Allergic reactions to certain foods and medications are common causes of hives.
Hives typically are the result of an allergic reaction; however, there are many nonallergic causes. Finding the exact cause can be difficult.
What Are the Different Types of Hives?
This type of hives is usually the result of an allergic reaction.
These hives may appear within a short time (from a few minutes to a few hours) after consuming certain foods or medications, or after applying certain chemicals to the skin; they also may be a reaction to an infection. People with this type of reaction may be able to identify and eliminate the cause. Acute hives typically last only a few hours.
If you have this condition, you will experience multiple cases of hives over a period of time. The cause may include medications, hidden infections or other internal problems. While testing — such as allergy tests, bloodwork or a skin biopsy — may be helpful in some cases, it may not be possible to identify the cause of your hives.
This type of chronic hives is caused by one or more physical sources, such as sunlight, heat, cold, water, pressure, vibration or exercise.
- Dermatographic urticaria forms after rubbing or scratching the skin, and can often occur with other forms of hives. This is the most common form of physical hives. These hives appear within a few minutes along the path of rubbing or scratching and last less than an hour.
- Sun hives (solar urticaria) form within minutes of sun exposure and typically fade one to two hours after you get out of the sun.
- Cold hives (cold urticaria) appear when the skin warms after exposure to cold or after prolonged chilling — when swimming, for example. These hives can cause wheezing, flushing and fainting.
- Pressure hives can appear on parts of the body that have pressure on them for long periods of time, like the area at the top of the ankle where a sock band is tight. These hives may take hours to appear.
What Foods Cause Hives?
In children, the most common foods that cause hives are milk, eggs and peanuts. In adults, nuts, shellfish and eggs are the most common foods that cause hives.
Fresh foods cause hives more often than cooked foods. Strawberries, food additives and preservatives are also known to trigger hives.
What Drugs Cause Hives?
Almost any prescription or over-the-counter medication can cause hives, as can “herbal” or “natural” remedies.
To help determine the cause of your hives, it is important to tell your dermatologist about all prescription and over-the-counter medications you’re taking, as well as any herbal or natural products you use.
What Type of Infections Can Cause Hives?
Upper respiratory tract infections and colds can trigger an outbreak of hives, especially in children.
Viral, bacterial and fungal infections also can cause hives.
How Does a Dermatologist Treat Hives?
Most hives disappear in a few hours or a day. An over-the-counter antihistamine can provide relief and reduce itchiness. There are many antihistamines available, and no single antihistamine works for everyone. You may have to try several types until you find the one that is most effective for you.
If you have hives that do not go away within 24 hours or do not respond to over-the-counter antihistamines, see a board-certified dermatologist.
Your dermatologist may prescribe a higher dose of antihistamines or combine them with other medications to control your hives. Oral corticosteroids may provide temporary relief but should be taken for only a short period of time.
If your hives continue regularly for six weeks or longer and your current medications are not controlling them, you may have chronic idiopathic urticaria. In this case, your dermatologist may prescribe omalizumab, a biologic medication approved by the FDA in 2014; an anti-inflammatory medication called cyclosporine, which can modify the body’s immune response; or dapsone, an antibiotic with anti-inflammatory properties. Talk with your dermatologist about which medication may be right for you.
In severe cases, an injection of epinephrine may be necessary. Always seek immediate emergency medical treatment if you experience difficulty breathing.
A board-certified dermatologist is a medical doctor who specializes in the diagnosis and medical, surgical and cosmetic treatment of skin, hair and nail conditions. To learn more about hives or to find a board-certified dermatologist in your area, visit aad.org/hives or call toll-free (888) 462-DERM (3376).
All content solely developed by the American Academy of Dermatology.
Copyright © by the American Academy of Dermatology and the American Academy of Dermatology Association.
Images used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides
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