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Hives, or urticaria, are itchy, raised welts that are found on the skin. Hives are often caused by an allergic reaction.

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What Are Hives?

Hives, also known as urticaria, are itchy, raised welts that are found on the skin. They may be red and painful to touch. In most cases, hives are caused by an adverse reaction to medication or an allergic reaction to an irritant.

What Causes Hives?

Hives are usually caused by an allergic reaction to something that you have encountered or swallowed. When you are having an allergic reaction, your body begins to release histamines into your blood. Histamines are chemicals your body produces in an attempt to defend itself against infection and other outside intruders. Unfortunately, in some people, the histamines can cause swelling, itching, and many of the symptoms that are experienced with hives. In terms of allergens, hives can be caused by factors such as pollen, medications, animal dander, and insect bites.

It should be noted that hives might also be caused by circumstances besides allergies. It is not uncommon for people to experience hives as the result of stress, tight clothes, exercise, illnesses, or infections. It is also possible to develop hives as the result of excessive exposure to hot or cold temperatures or from irritation due to excessive sweating. As there are many potential causes, sometimes the actual cause of hives cannot be determined.

Who Is at Risk?

People who are known to have allergies are more likely to get hives. You may also be at risk to develop hives if you are on medication or if you are unknowingly exposed to things you may be allergic to, such as food or experiencing hay fever. If you are already ill with an infection or a condition, you may be more vulnerable to developing hives.

What Do Hives Look Like?

The most noticeable symptom associated with hives is the welts that appear on the skin. Welts may be red but can also be the same color as your skin. They can be small and round, ring-shaped, or large and of random shape. Hives are usually itchy, and tend to appear in batches on the affected part of the body. They can grow larger, change shape, and spread.

Hives may disappear or reappear over the course of the outbreak. Individual hives can last anywhere from half an hour to a day and a half. If you touch the hives, it may be painful and you may notice that the area turns slightly white. Sometimes the hives may change shape or form together and create a larger, raised area. Hives can occur in a variety of places on the body. If you are experiencing an outbreak on your tongue or around your throat and the area begins to swell, it is recommended that you see your doctor or get medical attention as soon as possible.

Finding Relief: Treatment Options

The first step in getting treatment is to figure out the cause of the hives. In most cases, your doctor will be able to determine if you have hives from a physical exam. Your skin will show signs of the welts that are associated with hives. Your doctor may also perform blood tests or skin tests to determine what may have caused your hives — especially if it was a result of an allergic reaction.

If you are experiencing a mild case of hives that could resolve itself in a period of time, you may not need any treatment. In these circumstances, your doctor might suggest that you seek temporary relief by:

  • taking antihistamines, such as diphenhydramine
  • avoiding irritating the area
  • avoiding hot water, which may aggravate the hives

In more severe cases of hives or those that could become emergencies, your doctor may use a shot of steroids or epinephrine to relieve the symptoms more quickly.

What to Expect

Although hives can be itchy and painful, usually they are not severe and will disappear after a period of time. According to the Mayo Clinic, each individual hive will go away in as little as 30 minutes, but could also last up to 36 days. However, be aware that as some hives go away, new ones may pop up.

If you are not experiencing a severe case of hives, they are considered to be harmless. In situations where you are having a serious allergic reaction and throat swelling may block your airway, hives can be more dangerous. Getting proper treatment in a severe case of hives is important for ideal recovery.

Can Hives Be Prevented?

Simple changes to your lifestyle may be able to help you prevent hives from reoccurring in the future. If you have allergies and you know which substances are likely to cause an allergic reaction, your doctor will likely suggest that you avoid any possible exposure to these factors. Allergy shots are another option that may help you reduce the risk of experiencing hives again. If you have just recently had a hives outbreak, you may also want to consider avoiding wearing tight clothing or being in high-humidity areas, as this may cause another outbreak.

Written by: The Healthline Editorial Team
Edited by:
Medically Reviewed by:
Published: Jul 25, 2012
Published By: Healthline Networks, Inc.
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