Images of Urticaria (Hives)
Urticaria is the medical term for hives. Hives form when an allergen (something that causes an allergic reaction, such as a lotion, food, or drug) initiates a response from the body's immune system. A chemical in our bodies called histamine is released from cells, which causes small red, soft bumps to appear on the skin. Hives look similar to and are often mistaken for bug bites. They are very itchy and can appear all over the body once an allergen is encountered. A single hive can last for a few hours before fading, during which time new hives may appear.
Although sometimes the exact cause of hives is unknown, the following is a list of possible triggers: foods such as peanuts, shellfish, and eggs; environmental allergies such as pollen, trees, and animal dander; and medications such as antibiotics, aspirin, and painkillers.
Who's at risk?
All populations of people are susceptible to hives if they come into contact with something the body has an allergic response to. Infants are particularly susceptible to many rashes as their skin is very sensitive, and they may develop hives after applying a lotion or cream to which their body forms a reaction.
Signs and Symptoms
The most common locations for hives include:
- Upper arms or upper legs
Individual lesions of hives appear as 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 usually appears 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 your child is experiencing mild hives, you might have him or her:
- 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
If your child's hives make it difficult to breathe or swallow, or if your child feels lightheaded, call 911.
In other, non-urgent situations, see your child's doctor if the hives do not improve with self-care or if they continue to appear for more than a few days.
Before visiting your child's doctor, try to notice what might be triggering your child's 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 your child may have taken recently. Also, recall any recent illnesses your child might have had since some illnesses (or their treatments) can trigger hives.
Treatments Your Physician May Prescribe
After confirming that your child has hives, the doctor will work with you and your child to discover the possible cause. The doctor will take a detailed medical history and may do blood tests, urine tests, or X-rays.
The best treatment for hives is to discover any triggers and stop your child's exposure to them. However, as 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, hydroxyzine, or cetirizine
- Non-sleep-causing (non-sedating) type-1 antihistamines such as loratadine, fexofenadine, or desloratadine
- Type-2 antihistamines such as anitidine, 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.