Urticaria Usually Strikes Suddenly
First the skin itches, then it erupts into red welts. The itching may be severe, keeping people from working or sleeping. It’s a distressing disorder which affects an estimated 20 percent of the population at one time or another in their lives.
Commonly known as hives, urticaria has two forms: most cases are acute (lasting from a few hours to less than six weeks); some are chronic (lasting more than six weeks). The welts may appear in one place, disappear after a short time, then erupt at another spot, then another. They are made worse by scratching. Each individual hive lasts no more than 24 hours.
What kinds of things can trigger attacks of urticaria?
Bouts of urticaria have been traced to such triggers as certain foods, and additives,infections, drugs(including aspirin), cold, sun exposure, insect stings, alcohol, exercise, and endocrine disorders and emotional stress. In some people, pressure caused by belts and constricting clothing causes eruption. Urticaria may be a response to infection including the common cold, strep throat and infectious mononucleosis.
How are each person’s urticaria “triggers” identified?
In some cases, the trigger is obvious – a person eats strawberries or shrimp, then develops urticaria within a short time. But because there are so many possible causes for urticaria, other cases require determined detective work on the part of the physician and, sometimes, forbearance on the part of the patient.
To unravel the urticaria puzzle, your allergist will take a detailed history, looking for clues in your lifestyle that will help pinpoint the cause of your symptoms. You’ll be asked about the frequency and severity of your symptoms…your family’s medical history…medications you are taking…your work and home environment…and miscellaneous matters. In some cases you may require tests to analyze blood and urine, and other procedures such as x-rays. Although skin tests are not routinely performed, they may provide useful information in some cases. Your allergist will decide which tests to order based on the different types of urticaria and the suspected cause.
What are the different types of urticaria?
They can be classified into two categories: Immunologic and Non-Immunologic. Allergic or Immunologic Urticaria is the least common form. It is caused by the immune system’s overreaction to foods, drugs, infection, insect stings, blood transfusions or other substances. Foods such as eggs, nuts and shellfish, and drugs such as penicillin and sulfa are common causes of allergic or immunologic urticaria. Non-Immunologic Urticaria are those types of urticaria where a clear-cut allergic basis cannot be proven. These take many forms. Dermographism is urticaria that develops when the skin is stroked with a firm object. Cold-Induced Urticariaappears after a person is exposed to low temperatures – for example, after a plunge into a swimming pool or when and ice cube is placed against skin. Cholinergic Uriticaria, which is associated with exercise, hot showers and/or anxiety, is a form of hives that is related to release of certain chemicals from parts of the nervous system that control such body functions as blood pressure and heart rate. Pressure Urticaria develops from the constant pressure of constricting clothing such as sock bands, bra straps, belts or other tight clothing. Solar Urticaria arises on parts of the body exposed to the sun; this may occur within a few minutes after exposure. Some cases of non-immunologic urticaria may be caused by non-allergic reactions to aspirin and, possibly certain food dyes, sulfites,and other food additives. In many cases, particularly in chronic urticaria the trigger for the problem can’t be found; in this instance it is called Idiopathic Urticaria.
How is urticaria treated?
Your allergist first will alleviate the discomfort with medications; for example, antihistamines. Severe attacks of urticaria can be temporarily relieved by injections of epinephrine; rarely in these cases corticosteroids may be prescribed for a short period. Other drugs may be required for specific types of urticaria.
Of course, if the cause can be identified, the best course of treatment is avoidance of the substance that triggers urticaria. If a problem with a specific food is strongly suspected, then it should be avoided. This may require a careful reading of packaged food labels and inquiry about ingredients in restaurant meals.
American College of Allergy and Immunology
800 East Northwest Highway
Palatine, IL 60067
Provided in cooperation with the Asthma & Allergy Foundation of America and the American Academy of Allergy & Immunology