To diagnose an allergy, the first thing your doctor
does is talk with you. He’ll discuss your symptoms,
any medications you’re currently taking, and your
personal and family history. A physical examination is
also necessary.
The next step is the tests. There are 3 types of
tests. The skin test, patch test or blood test.
The skin test is the most common test used. It’s
generally the most accurate and certainly the least
expensive. With the skin test, a small amount of an
allergen is put on your skin and then the spot is
pricked or scratched with a needle. You can also have
a little bit of the allergen injected into the outer
layer of your skin.
If you have an allergy to the substance that was used,
you’ll have swelling, redness and itching in the
tested spot within 20 minutes.
The patch test is used to diagnose contact dermatitis.
A small amount of allergen is put on your skin and
covered with a bandage. Your doctor will check the
spot in 48 hours to see if you’ve developed a rash.
The third type of test is the blood test. This may be
used if you have a skin condition or if you’re taking
some type of medication that might interfere with a
skin test.
A blood sample is taken and sent to a laboratory.
There they add allergens to the sample and measure the
amount of antibodies that are produced to attack it.