Urticaria (Hives)

Hives (Urticaria)

Overview

Hives (urticaria), also known as welts, is a common skin condition with an itchy rash of pink to red bumps that appear and disappear anywhere on the body. An individual lesion of hives typically lasts a few hours (up to 24 hours) before fading away, and new hives can appear as older areas disappear. 

Physicians arbitrarily divide hives into acute (new or periodic episodes lasting fewer than 6 weeks) and chronic (periodic episodes lasting more than 6 weeks). Though many people have a single episode of acute hives that goes away within a few days to weeks, some individuals may have chronic hives that persist intermittently for years. More often than not, the offending agent is never identified in those who suffer from chronic hives. 

Hives can be triggered by many things, including: 

• Medications, especially aspirin, ibuprofen, naproxen, narcotic painkillers, and antibiotics Infections with viruses, bacteria, or fungi 
• Environmental allergies such as insect bites, pollen, mold, and animal dander 
• Physical exposures such as heat, cold, water, sunlight, and pressure 
• Medical conditions including some blood diseases and cancer 
• Food allergies such as from strawberries, eggs, nuts, and shellfish 
• Stress 

In many cases, the causative agent is not identified despite extensive testing. This is referred to as idiopathic urticaria. In approximately 50% of idiopathic urticaria outbreaks, hives are most likely caused by a reaction from the person's own immune system (autoimmune reaction).

Who's At Risk

Hives appear in people of all ages, of all races, and of both sexes.

Acute hives are most common in children and young adults, and chronic hives are more often seen in females, especially middle-aged women.

Hives are very common; it is estimated that up to 20% of the population may develop them at some point in their lives.

Signs and Symptoms

The most common locations for hives include:

• Trunk
• Upper arms or upper legs
• Hands and feet
• Face

An individual lesion of hives appears as a well-defined pink-to-red swelling, ranging in size from 2 mm to over 30 cm. Some lesions may develop a lighter center. Hives usually appear in groups or batches. They are classically incredibly itchy. Individual lesions of hives disappear within 24 hours, though a single episode with the development of new lesions may last much longer. 

Dermographism is a type of urticarial reaction that appears within a few minutes of scratching the skin. The rash is usually seen in a straight line (linear) pattern. This is usually a sign of a person with sensitive skin.

Swelling of the eyes, mouth, hands, feet, or genitals can sometimes occur with hives. This swelling, called angioedema, usually goes away within 24 hours, but it can be quite severe and life-threatening when swelling of the airway occurs.

Usually itchy, hives can also burn or sting.

Self-Care Guidelines

If you are experiencing mild hives, you might:

• Take cool showers.
• Apply cool compresses.
• Wear loose-fitting clothes.
• Avoid strenuous activity.
• Use an over-the-counter antihistamine such as diphenhydramine or loratadine.

In addition, try to discover what is triggering your hives and avoid whatever it might be. In particular, pay attention to any new foods that were ingested or new medications that were started.

When to Seek Medical Care

Call 911 if you are feeling lightheaded or are having difficulty breathing or swallowing associated with your hives.

In non-urgent situations with hives, see your doctor if the hives do not improve with treatment or if they continue to appear for more than a few days.

Before visiting your doctor, try to notice what might be triggering your hives and whether it improves or worsens with exposure to heat, cold, pressure, or vibration. Take a list of every medication (prescription or over-the-counter), supplement, or herbal remedy you may have taken recently. Also, recall any recent illnesses you may have had since some illnesses (or their treatments) can trigger hives.

Treatments Your Physician May Prescribe

After confirming that you have hives, the physician will work with you to discover the possible cause. Your doctor will take a detailed medical history and may do blood work, urine tests, or X-rays.

Obviously, the best treatment for hives is to discover any triggers and stop your exposure to them. However, most people with hives do not know the cause, and they require medications to get rid of them.

The most common medications for hives include:

• Sleep-causing (sedating) type-1 antihistamines such as diphenhydramine or hydroxyzine
• Non-sleep-causing (non-sedating) type-1 antihistamines such as loratadine, fexofenadine, desloratadine, or cetirizine
• Type-2 antihistamines such as ranitidine, cimetidine, or famotidine
• Doxepin
• Montelukast, zafirlukast, or zileuton

In rare situations, your doctor might prescribe oral corticosteroid pills.

Trusted Links

MedlinePlus: Hives

References

Bolognia, Jean L., ed. Dermatology, pp.287-302. New York: Mosby, 2003.

Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6^th ed. pp.547, 1129, 1137. New York: McGraw-Hill, 2003.