Skin Testing for Outdoor Allergies

If you sneeze and sniffle when you walk down the street and wonder if hay fever is the cause, skin testing may be the answer. It's a simple, easy way to find out whether pollen or mold are the triggers of your symptoms.

How It Works

When you breathe in something you're allergic to, like ragweed, your body reacts. You'll have symptoms like itchy eyes and a runny nose. Skin testing also triggers an allergic reaction, but only on your skin.

During the test, your doctor pricks you with a tiny amount of an allergy trigger. It's safe and not very painful. If you're not allergic, nothing will happen. If you are, the area will swell and itch like a mosquito bite.

Skin Test Types

There are two basic kinds:

Standard test. Your doctor puts a tiny amount of the allergy trigger on your skin, usually on your back or forearm, and then pricks or scratches the skin beneath.

Intradermal tests. For this type, your doctor will use a needle to inject the allergy trigger a little deeper under the skin of your arm. You may need this only if the standard test has unclear results.

Your doctor will probably test for many things at once. He'll give you a physical exam and ask you questions, too. After the test and exam, he should have a good sense of what triggers your allergies and what doesn't.

Skin tests are accurate, but they're not perfect. Sometimes the results aren't clear. It's important to work with a doctor who has a lot of experience with allergy testing.

Side Effects

If your body reacts to the allergy, you'll have swelling and some itchiness where the doctor injected it. These symptoms usually start within 15 minutes and fade away within 30 minutes. Some people have a delayed reaction 24 to 48 hours later.

More-serious allergic reactions are rare. To be safe, doctors always do allergy testing in an office where they can watch you.

Next Steps

After skin testing, your doctor can tailor your treatment to your needs. Some things he may suggest:

More tests. He may recommend this if the results from the first round aren't clear. He may ask you to take something called "challenge testing." For this, you breathe in small amounts of an allergy trigger. He might also ask you to take blood tests.

Avoid allergy triggers. Once you know what you're allergic to, you can take steps to avoid making contact with it. For instance, if tree pollen triggers your hay fever, keep windows to your home shut when there's a lot of it in the air.

Medication or allergy shots. Your doctor may prescribe medicine to curb your symptoms or may suggest you start a series of allergy injections.

WebMD Medical Reference Reviewed by Jennifer Robinson, MD on December 16, 2018

Sources

SOURCES:

American Academy of Allergy, Asthma & Immunology: "Allergy Testing: Tips to Remember," "All About Allergy Testing." 

American College of Allergy, Asthma, & Immunology: "Allergy Testing."

Asthma and Allergy Foundation of America: "Skin Testing to Diagnose Allergies."

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