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Allergy Testing
Why is allergy testing important?
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 allergy
treatment. 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.
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?
There are two types of skin tests. During the first type of skin
test, a drop of a suspected allergen is pricked or scratched on the
surface of the skin. The test is performed on the back or forearm.
Many suspected allergens are tested at the same time. If you are
allergic to one of the tests, you will have redness and swelling at
the test spot.
Sometimes the
doctor will recommend a second type of test. In this type, a small
amount of the suspected allergen is injected into the skin of the
arm or forearm. Several suspected allergens are tested at the same
time.
How long does it take to get skin
test results?
Skin testing is fast. For both types of skin tests, positive
reactions usually appear within 20 minutes. Sometimes redness and
swelling can occur several hours after skin testing. The delayed
reaction usually disappears in 24 to 48 hours, but should be
reported to the allergy doctor or nurse.
Is skin testing painful?
Both types of skin 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 takes
many days to get the results.
Which test method is best?
Skin tests give fast results. They usually cost less than allergy
blood tests. 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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