Images of Urticaria (Hives)
Urticaria is the medical term for hives, which are a very common, bothersome skin condition in which the skin raises up into itchy welts that may last for hours to weeks. The welts are usually related to an allergy, though there are many triggers for hives. The welts tend to be pale pink or flesh-colored and very slightly raised above the skin surface; they can be as small as fingertip size or can run together and cover very large areas. During the course of an attack of hives, the welts can come and go and change quite rapidly.
There are 2 kinds of hives: acute hives, in which the welts last less than 6 weeks, and chronic hives, in which the welts last longer than 6 weeks. Chronic hives are less understood and may have more complicated triggers than acute hives. Some examples of common triggers include anything that the affected person is allergic to, including foods (especially peanuts and shellfish), drugs, and environmental exposures. Less common triggers include extreme body heat (such as a hot shower) or cold (such as outdoor temperature), some medications, pressure or scratching of the skin, and exercise. Very rare triggers include sunlight, water, and a reaction to adrenaline. Because there are so many triggers for hives, it can be very difficult to identify the correct trigger, and many cases of hives are called "idiopathic," meaning the diagnosis is uncertain. However, because the development of hives may indicate an allergic process, it is important to keep your doctor aware of your hives so that you can be counseled about allergy safety.
Who's at risk?
Anyone of any age can develop hives. Acute hives are more common in children and teens, and chronic hives seen most often in adult women.
Signs and Symptoms
The most common locations for hives includes:
- Upper arms or upper legs
An individual hive lesion appears as a well-defined, pink-to-red swellings ranging in size from 2 mm to over 30 cm. Some lesions may develop a lighter center. Hives usually appear in groups or batches.
Individual lesions of hives disappear within 24 hours, though a single episode may last much longer.
Dermographism is a type of hives that appears within a few minutes of scratching the skin. The rash is usually seen in a straight line (linear) pattern.
Swelling of the eyes, mouth, hands, feet, or genitals can sometimes occur with hives. This swelling, called angioedema, usually goes away within 24 hours.
Usually itchy, hives can also burn or sting.
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
When to Seek Medical Care
Call 911 if your hives cause you to have difficulty breathing or swallowing or if you feel lightheaded.
In other non-urgent situations, 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 might 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 the cause(s) and stop your exposure to them. However, most people with hives do not know the cause, and they require medications to get rid of the hives.
The most common medications for hives include:
- Sleep-causing (sedating) type-1 antihistamines such as diphenhydramine, hydroxyzine, or cetirizine
- Non-sleep-causing (non-sedating) type-1 antihistamines such as loratadine, fexofenadine, or desloratadine
- Type-2 antihistamines such as ranitidine, cimetidine, or famotidine
- Montelukast, zafirlukast, or zileuton
Bolognia, Jean L., ed. Dermatology, pp.287-302. New York: Mosby, 2003.
Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6th ed. pp.547, 1129, 1137. New York: McGraw-Hill, 2003.