After eating some big, juicy strawberries, you decide to walk to your friend's house. Just as you're turning the corner, you notice reddish bumps and patches on your arms and chest. What are these itchy welts or blotches on your skin? Should you turn around and head home?

What Are Hives?

Hives are pink or red bumps or slightly raised patches of skin. Sometimes, they have a pale center. Hives usually itch, but they also can burn or sting.

Hives can occur anywhere on the body and vary in size and shape. They can be small like a mosquito bite or big like a dinner plate. Hives also might look like rings or groups of rings joined together. Hives can appear in clusters and might change locations in a matter of hours. A bunch of hives might be on a person's face, then those might go away. Later, more may appear on a person's arms.

Hives are common — between 10% and 25% of people get them at least once in their lives. They are usually harmless, though they occasionally can be a sign of a serious allergic reaction. (So, yes, you should go home and tell your mom or dad.)

The medical term for hives is urticaria (say: ur-tuh-kar-ee-uh). When a person is exposed to something that can trigger hives, certain cells in the body release histamine (say: his-tuh-meen) and other substances. This causes fluid to leak from the small blood vessels under the skin. When this fluid collects under the skin, it forms the blotches, which we call hives.

Why Do I Get Hives?

People can get hives for lots of different reasons. Often, the cause is not known.

One common reason for getting hives is an allergic reaction. Some common allergic triggers are certain foods (like milk, shellfish, berries, and nuts), medications (such as antibiotics), and insect stings or bites.

Other causes of hives are not related to allergies and these can include:

• exposure to the cold (like diving into a cold pool)
• exercise
• sun exposure
• nervousness or stress
• infections caused by viruses

No matter what the cause, a case of hives can last for a few minutes, a few hours, or even days.

What Will the Doctor Do?

Doctors usually can diagnose hives just by looking at you and hearing your story about what happened. The doctor can try to help figure out what might be causing your hives, although often the cause will remain a mystery. If you're getting hives a lot, or your reaction was serious, your doctor might send you to another doctor who specializes in allergies.

Sometimes, doctors will suggest you take a type of medication called an antihistamine to relieve the itchiness. In many cases, hives clear up on their own without any medication or doctor visits.

Less often, hives can be a sign of a more serious allergic reaction that can affect breathing and other body functions. In these cases, the person needs immediate medical care.

Some people who know they have serious allergies carry a special medicine to use in an emergency. This medicine, called epinephrine, is given by a shot. Ordinarily, a nurse gives you a shot, but because some allergic reactions can happen really fast, many adults and kids carry this emergency shot with them and know how to use it, just in case they ever need it in a hurry.

Can I Prevent Hives?

Yes and no. The answer is "yes" if you know what causes your hives — the strawberries at the start of this article, for example. If you know they cause you trouble, you can just avoid them. If you get hives when you're nervous, relaxation breathing exercises may help. But if you don't know why you get hives, it's tough to prevent them.

Some kids get hives when they have a virus, such as a bad cold or a stomach flu. Other than washing your hands regularly, there's not much you can do to avoid getting sick occasionally.

The good news is that hives usually aren't serious and you might even grow out of them. Who wouldn't want to give hives the heave-ho?

Reviewed by: Christopher C Chang, MD
Date reviewed: June 2011