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Common Conditions -
Allergy Testing
More than
50 million people in the United States have
allergies. Finding out what you are allergic to
is an important first step to effective
treatment. Many rashes and skin irritations are
due to allergies. Today allergy tests are more
convenient and accurate than ever before. When
combined with a detailed medical history,
allergy testing can identify the specific things
that trigger your allergic reactions. Dr. Moore
and her staff offer a number of allergy tests to
help you determine the cause of a persistent
rash or irritation.
Who can be tested for allergies?
Adults and children of any age can be tested for
allergies.
How are allergy tests done?
Allergy testing can be done as skin tests or as
blood tests. Usually, allergy tests are done
under the guidance of an allergy specialist.
These specialists are trained in the best
methods for testing and treating allergies.
How do allergy skin tests work?
A dermatologist will study the materials that
your skin encounters at work and at play to try
to identify the allergen. Most contact
dermatitis is diagnosed by distribution of the
rash. Sometimes the cause cannot be identified
by history or physical examination and your
dermatologist may want to perform patch tests.
Patch tests are a safe and easy way to diagnose
contact allergies. Patch tests are different
from injection or scratch skin tests because
they test for different allergens. In patch
tests, small amounts of the possible common
allergens are applied to the skin on strips of
tape and then removed after two days. A positive
allergy test shows up as a small red spot at the
site of the patch.
Common allergens include nickel, rubber, dyes,
preservatives, medications, fragrances, poison
ivy, poison oak, and related plants.
How long does it take to get skin test
results?
Skin testing does take a full week. We apply
"patches" and then ask the patient to return for
two more visits to monitor reactions and make a
determination of what your skin is allergic to.
Is skin testing painful?
Patch tests have little or no pain.
However, positive reactions cause annoying
itching red bumps which look and feel like
mosquito bites. The itching and bumps are gone
usually in just a few short minutes or hours.
Does medicine interfere with allergy skin
tests?
Some medicines do interfere with allergy skin
tests. The allergist will tell you if you have
to change your medicine before allergy skin
testing.
When are allergy blood tests used?
An allergy blood test is often used because:
- The patient
is taking a medicine that can interfere with
skin testing, but cannot be stopped for a
few days
- The patient
suffers from a severe skin condition such as
eczema or psoriasis
- Testing with
a strong allergen might cause an extra large
positive reaction
- For babies
and very young children, a single needle
stick for allergy blood testing may be
better than several skin tests.
How
long does it take to get blood test results?
Because the blood sample must be sent to a
lab for testing, it may take a few days to
get the results.
Which test method is best?
Patch tests give fast results. What are
the negatives? Young children do not like
this type of test. Some medicines can
interfere with the tests. In addition, in
some people with dark skin it may be hard to
read the tests. Also, the skill of the
tester may affect the results. The test
should be done by a person with lots of
training.
Blood tests are helpful because they involve
a single needle prick. Medicine does not
interfere with the results. However, it
takes a long time to get the results. Blood
tests cost more than skin tests. There are
many of types of allergy blood tests. Some
types are more helpful than others.
Each test method has pluses and minuses. The
test results alone do not diagnose
allergies. All test results, from either
type of test, must be interpreted together
with the medical history.
Are there risks or side effects from
allergy testing?
Any medical test involves some risk. The
risk with allergy skin tests is that allergy
symptoms might occur during the test. The
most common symptoms are itching and
swelling of the skin where the tests are. In
rare cases, a more serious reaction can
occur. That is why skin tests should be done
by a specialist. The risk with allergy blood
tests is pain or bleeding at the needle
mark. Also, a few people may faint during
blood testing.
What allergies can allergy testing
find?
Allergy tests help find allergies to pollen,
molds, dust mites, animal dander, insect
stings, foods and some medicines.
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