URTICARIA
What is Urticaria (Hives) ?
Urticaria or hives as it is commonly called, is an itchy rash
consisting of localized swellings of the skin that usually last for a
few hours before fading away. When urticaria develops around loose
tissues of the eyes or lips, the affected area may swell excessively.
Although frightening in appearance, the swelling (called angio-oedema)
goes away in 12 to 24 hours with treatment.
How is urticaria produced ?
Urticaria results from some changes in the small blood vessels of
the skin. Such changes are brought about by the release of some
substances in the body, the commonest of which is histamine. Histamine
is released from cells called mast cells by either an allergic or
non-allergic reaction.
What causes single attacks of urticaria
?
Acute urticaria, which can last from a few hours to as long as a
week is usually caused by drugs, specific foods or a viral infection.
Sometimes, no cause can be detected.
What are the foods that can cause acute and
repeated attacks of urticaria ?
Foods that can cause urticaria include :
-
 Nuts
- Eggs
- Fresh fruits (especially citrus)
- Chocolates
- Fish and shellfish
- Tomatoes
- Milk and cheese
- Spices
- Yeasts
Foods additives and preservatives such as tartrazine (yellow dye)
may also be responsible. Hives may appear within minutes or several
hours after ingestion of the food depending on its rate of
absorption.
What are the drugs that can cause urticaria ?
Drugs that commonly cause urticaria include :
Pain killers/Anti-rheumatics e.g aspirin, codeine
Antibiotics e.g penicillins, sulphonamides
However, any drug should be suspected even if it has been taken for
a long time without ill effects previously. Drugs commonly cause acute
urticaria but they may also aggravate chronic
urticaria.
What else can cause urticaria ?
Recurring attacks of urticaria may be caused by physical agents such
as; sunlight, cold, pressure and sweat. Urticaria caused by such agents
is called physical urticaria. The causative agent is usually recognized
by the patient.
Chronic Urticaria
This is urticaria occurring almost daily and lasting more than two
months. In the majority of patients, no cause or significant aggravating
factors can be found. Physical urticaria may be present as well in some
patients. Food allergy is seldom a cause of chronic persistent urticaria
even though some foods may aggravate it. Infections such as candidiasis
(a kind of yeast infection) may be a cause, although, not common.
Emotional stress is known to aggravate chronic urticaria in some.
Fifty per cent of cases of chronic urticaria, clear spontaneously in
about 6 months.
How is urticaria treated ?
The best treatment for urticaria is to identify and avoid the cause
and any aggravating factors. While investigating the cause,
anti-histamines are prescribed for symptomatic relief. Antihistamines,
when taken orally, take about 90 minutes to relieve an already formed
hive. They work best if taken on a regular basic to prevent the
formation of hives. To avoid side-effects like drowsiness,
non-sedative antihistamines are available. Antihistamine creams are
ineffective.
Elimination diets are not helpful unless a particular food is
suspected. Skin tests are generally of no use. Blood and urine test
are sometimes carried out to exclude infection as a cause of chronic
urticaria.
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