Allergies
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.
-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.
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?
Some medicines
can interfere with the tests. The test should be done by a person with lots
of training.
Blood tests: 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. IgE testing is the
only valid blood test.
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.