What are hives?

Hives (urticaria) are raised, red, itchy areas on the skin (also called wheals or welts) that appear as an allergic skin reaction. There can be one or many hives that vary in size and shape.

How does it occur?

Most often, no cause for hives can be identified. Clusters of hives may appear as an allergic reaction to one or more factors (irritants) such as foods, medications, insect bites or stings, infections, or emotional stress.

Histamine, a body chemical, is released in response to the irritant that causes the hives to form. These hives or wheals may appear on any part of the body, but are most common on the arms, legs, and trunk. The rash may last for a few minutes or several days. It may recur and can be uncomfortable.

In the case of a severe reaction to a bee sting, for example, your face and throat may swell. Hives may rarely cause problems with breathing, creating the danger of suffocation.

How is it diagnosed?

Your doctor will examine the affected area and will ask about your history of sensitivity to such things as:

• foods (commonly eggs, shellfish, milk, nuts, berries, dyes or other additives)
• drugs (such as penicillin, aspirin, or sulfa)
• plants (such as nettles) and pollens
• animal fur
• insect bites or stings
• exposure to heat, cold, or sunshine.

To determine the cause of your hives, the doctor may suggest that you do the following:

• Keep a detailed diary of everything you eat, drink, take, or are exposed to for 2 to 4 weeks.
• Avoid foods, one at a time, to which you think you may be allergic.
• See an allergist for skin tests.

It is easiest to identify drugs, foods, or plants that may cause you to have hives because the response usually occurs within an hour. Finding what triggers hives such as emotional stress or multiple allergies may take more time and require skin or other tests.

How is it treated?

The treatment your doctor recommends will depend on how serious your hives are. He or she may suggest that you do one or more of the following to relieve the itching and reduce the swelling:

• Soak in a lukewarm bath or use cool compresses.
• Avoid heat or rubbing, which releases more histamines.
• Take antihistamine medicine to reduce the allergic response.

If the rash is severe and/or not responding to the above treatments, you may need to take a brief course of oral corticosteroids (for example, prednisone).

Have an adrenaline or steroid shot (usually with severe reactions such as anaphylactic shock, which affects the entire body and can be life-threatening because it can make breathing difficult).

Some allergic reactions are emergencies. If your hives have abrupt onset and are spreading quickly, you will likely receive an injection of antihistamine such as Benadryl (diphenhydramine). If there is any question of throat swelling or tightness or of difficult breathing or of wheezing, you will also receive an injection of epinephrine (adrenaline) to counteract the reaction. Once the emergency symptoms have been treated you will be instructed in medication to take for the next several hours to days to prevent the reaction from recurring.

These severe allergic reactions can be life-threatening and require immediate medical treatment.

How long will the effects of hives last?

The effects of hives can last from a few hours to several weeks or months. Hives will eventually clear without treatment, but taking drugs such as antihistamines or corticosteroids help the hives go away faster, treat the itch, and prevent new hive formation.

Chronic urticaria last for a longer period. Most often, more than 50% of the time, it is not possible to determine their cause. Antihistamines are usually very helpful. The hives resolve spontaneously after weeks or months but may recur off and on.

How can I take care of myself?

Call the doctor or 911 at once if you have an allergic response that affects your breathing. You should also call if you continue to have outbreaks of hives.

In addition, follow these guidelines:

• If your face begins to swell around the eyes and lips, call your doctor or 911 at once.
• Take antihistamines or other medications to help relieve your symptoms. Be sure to ask your doctor or pharmacist about possible side effects or drug interactions.
• Avoid foods that seem to cause you to break out.

If you have a known severe allergy, such as to a bee sting or a food such as peanuts, which you might inadvertently contact, ask your doctor about carrying Epipen. Epipen is a single-dose injection kit of epinephrine you can give yourself to counteract the allergic reaction until help arrives.

What can be done to help prevent hives from recurring?

When you know the cause of your hives you should take steps to avoid the offending irritant. You may need to take frequent, even daily, antihistamine to prevent recurrences.