Urticaria - Hives
Hives are pale red swellings of skin "wheals" that
occur in groups on any part of the skin. Urticaria is the medical word for
hives. Each hive lasts a few hours before fading without trace. New areas may
develop as old areas fade. They can vary in size from as small as a pencil
eraser to as large as a dinner plate and may join together to form larger
swellings. Hives are usually are itchy, but may also burn or sting.
Hives are formed by blood plasma leaking out of
small blood vessels in the skin. This is caused by the release of a chemical
called histamine. Histamine is released from cells called "mast cells" which lie
along the blood vessels in the skin. Allergic reactions, chemicals in foods, or
medications can cause histamine release. Sometimes it's impossible to find out
why hives are forming.
Hives are very common --10-20 percent of the
population will have at least one episode in their lifetime. Hives usually go
away within a few days to a few weeks. Occasionally, a person will continue to
have hives for many years.
When hives form around the eyes, lips or genitals,
the tissue may swell excessively. Although frightening, the swelling usually
goes away in less than 24 hours. Acute Urticaria
 Hives lasting less than six weeks are caused by "acute
urticaria". With this type of hives, the cause can usually be found. The most
common causes are foods, drugs or infections. Insect bites and internal disease
may also be responsible. Other causes can be pressure, cold, and sunlight.
The most common foods that cause hives are nuts,
chocolate, fish, tomatoes, eggs, fresh berries and milk. Fresh foods cause hives
more often than cooked foods. Food additives and preservatives may also be the
problem.
Hives may appear within minutes or up to two hours
after eating, depending on where the food is absorbed in the digestive
tract.
 Almost any prescription or over-the-counter medication can
cause hives. Some of those drugs include antibiotics, pain medications,
sedatives, tranquilizers, and diuretics. Antacids, vitamins, eye and ear drops,
laxatives, vaginal douches, or any other non-prescription item can be a
potential cause of hives. If you have an attack of hives, it's important to tell
your doctor about all of the preparations that you use to assist in finding the
cause.
Many infections can cause hives. Colds are a
common cause in children.
 Hives lasting more than six weeks are called "chronic
urticaria". The cause of this type of hives is usually much more difficult to
identify than that of acute urticaria. In patients with chronic urticaria, the
cause is found in only a small number of patients. Your doctor will need to ask
many questions in an attempt to find the possible cause. Since there are no
specific tests for hives, testing will depend on your medical history and a
thorough examination by your dermatologist. Routine blood tests are of little or
no value.
Hives can be caused by sunlight, cold, pressure,
vibration, or exercise. Hives due to sunlight are called solar urticaria. This
is a rare disorder in which hives from within minutes of sun exposure on exposed
areas and fade within one to two hours. Hives due to the cold are more common.
These appear when the skin is warmed after exposure to cold. If the cold is over
large areas of the body, large amounts of histamine may be released which can
produce wheezing, flushing, generalized hives, and fainting. A simple test for
this type of hives can be done by applying an ice cube to the skin.
These hives can form after firmly stroking or
scratching the skin "dermatographism". It affects about 5 percent of the
population. Most people with this condition are otherwise healthy. These hives
can also occur along with other forms of urticaria. If it is present along with
hives, finding and eliminating the cause usually clears the dermatographism.
Otherwise, it may last for months or even years.
The best treatment for hives is to find and remove
the cause. This is not an easy task. Antihistamines are usually prescribed by
your dermatologist to provide relief. Antihistamines work best if taken on a
regular schedule to prevent hives from forming. No one antihistamine works best
for everyone, so your dermatologist may need to try more than one or different
combinations to find what works best for you.
In severe hives, an injection of epinephrine
(adrenalin) or a cortisone medication may be needed.
| 
