Few conditions are more annoying than urticaria, better known as hives. Not only can these little welts be uncomfortable and unsightly, they can also be a sign of a more serious medical condition. Fortunately, most cases of urticaria are benign and are usually caused by allergy. The allergens can be inhaled through the nose, ingested as food, grow on the body as yeast or make contact with the skin. Non-allergic causes or serious medical causes must be worked up independently through a series of blood tests, biopsies or special examinations. For the remainder of this column, we will focus on allergic urticaria, or hives due to allergies.
Let’s separate urticaria from eczema. Both are skin rashes and both can come from allergies. Hives are itchy, red splotches that arise quickly and may resolve quickly. They usually don’t last more than a few days, although they may become chronic or recurrent. They are usually associated with other allergy symptoms, such as runny nose, sneezing and sometimes asthma. Urticaria usually occurs when there is a sudden and significant rise in the allergen load that a person is experiencing. For example, he may play with a cat after eating a peanut butter cracker, after coming inside on a high pollen day. Each of these allergens alone may cause fewer symptoms, but together the perfect storm is created and the hives occur.
Eczema is a collection of inflamed, red rashes that arise more slowly and tend to last much longer. The skin may break down and ooze, or it may become dry and scaly. The rashes may become infected. There tends to be less itching with eczema than there is with urticaria. Eczema is more often chronic, and the cause is more difficult to detect. Reactions to medications, chemicals, dyes, metals and detergents may be involved. Yeast growing on the body may be the source of chronic eczema.
The workup for urticaria and eczema is similar, though it may vary depending on the patient’s symptoms. The main diagnostic tool is allergy testing. Generally, skin testing will be performed for pollens, molds, animal danders, dust mites and cockroaches, foods and body yeast. Blood testing may be employed if no skin surface is free of rash, though blood testing is less accurate than skin testing. Patch testing is applied to unaffected skin to rule out various allergens that come directly into contact with the skin. Lab work is usually performed to rule out various non-allergic causes that may be found in the bloodstream.
Treatment for urticaria generally involves stopping the itch. Antihistamines are employed for this purpose. Frequently, both type 1 and type 2 antihistamines are necessary. Both classes are available over the counter. Ask your doctor or pharmacist. Type 1 are the common antihistamines used for runny nose and sneezing. Type 2 are often sold for acid reflux. Oral steroids may be given in both urticaria and eczema to decrease the inflammation and to clear the rash. Topical steroids may also be employed. Antibiotics may be necessary if a rash becomes infected. Controlling nasal allergy symptoms and asthma symptoms may also be necessary. The best long-term treatment plan for chronic urticaria or eczema involves allergy shots or drops. Injectable biological agents have also proven effective.