Skin Testing for Indoor Allergies

If you think you're allergic to something inside your home -- like dust mites, mold, or cockroaches -- skin tests can help you figure out the culprit.

How Allergy Skin Tests Work

When you breathe in an allergy trigger, the immune system -- your body's defense against germs -- overreacts. You may have swelling, itchy eyes, and a runny nose.

Skin testing also sets off an allergic reaction, but only on your skin. Your doctor places a tiny amount of the allergy trigger on your body, usually on your back or forearm, and then pricks or scratches the skin underneath.

If nothing happens, you're not allergic to that trigger. If you are, you'll get a small, raised bump that itches like a mosquito bite. That's how your doctor can tell what's causing your symptoms.

What to Expect

Before your doctor does a skin test, he'll give you a physical exam and ask questions to get a sense of what brings on your allergies. He'll probably test for many allergy triggers at once.

Skin tests are accurate, but they're not perfect. It's important to work with an allergist who has a lot of experience with allergy testing.

Skin Testing Side Effects

If your body reacts to the allergy trigger, you'll have swelling and some itchiness at the site of the skin prick. These symptoms usually start within 15 minutes and fade within 30 minutes. Rarely, some people have a delayed reaction 24 to 48 hours later.

More serious allergic reactions are very 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 and give you advice on what to do next. You may need:

More testing. If results weren't clear, your doctor may want to do some more checks. Some people need blood tests or "challenge testing," in which you breathe in or take by mouth small amounts of the allergy trigger.

Changes at home. Once you know what you're allergic to, you can take steps to protect yourself. For instance, if dust mites are the problem, you can wrap your mattress in an allergy-proof cover to keep them out.

Medication or allergy shots. Your doctor may suggest medicine to control your symptoms. Allergy shots can also help, although they take much longer to work.

WebMD Medical Reference Reviewed by Jennifer Robinson, MD on October 27, 2018

Sources

SOURCES:

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

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

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