Dermatology

During allergy skin tests, your skin is exposed to suspected allergy-causing substances (allergens) and is then observed for signs of an allergic reaction.

Along with your medical history, allergy tests may be able to confirm whether or not a particular substance you touch, breathe or eat is causing symptoms.

Information from allergy tests may help your doctor develop an allergy treatment plan that includes allergen avoidance, medications or allergy shots (immunotherapy).

Allergy skin tests are widely used to help diagnose allergic conditions, including:

• Hay fever (allergic rhinitis)
• Allergic asthma
• Dermatitis (eczema)
• Food allergies
• Penicillin allergy
• Bee venom allergy
• Latex allergy

Skin tests are generally safe for adults and children of all ages, including infants. In certain circumstances, though, skin tests aren’t recommended. Your doctor may advise against skin testing if you:

Have ever had a severe allergic reaction. You may be so sensitive to certain substances that even the tiny amounts used in skin tests could trigger a life-threatening reaction (anaphylaxis).

Take medications that could interfere with test results. These include antihistamines, many antidepressants and some heartburn medications. Your doctor may determine that it’s better for you to continue taking these medications than to temporarily discontinue them in preparation for a skin test.

Have certain skin conditions. If severe eczema or psoriasis affects large areas of skin on your arms and back — the usual testing sites — there may not be enough clear, uninvolved skin to do an effective test. Other skin conditions, such as dermatographism, can cause unreliable test results.

Blood tests (in vitro immunoglobulin E antibody tests) can be useful for those who shouldn’t undergo skin tests. Blood tests aren’t done as often as skin tests because they can be less sensitive than skin tests and are more expensive.

In general, allergy skin tests are most reliable for diagnosing allergies to airborne substances, such as pollen, pet dander and dust mites. Skin testing may help diagnose food allergies. But because food allergies can be complex, you may need additional tests or procedures.

Before scheduling a skin test, bring your doctor a list of all of your prescription and over-the-counter medications. Some medications can suppress allergic reactions, preventing the skin testing from giving accurate results. Other medications may increase your risk of developing a severe allergic reaction during a test.

The most common side effect of skin testing is slightly swollen, red, itchy bumps (wheals). These wheals may be most noticeable during the test. In some people, though, an area of swelling, redness and itching may develop a few hours after the test and persist for as long as a couple of days.

Rarely, allergy skin tests can produce a severe, immediate allergic reaction, so it’s important to have skin tests performed at an office where appropriate emergency equipment and medications are available.

The most common side effect of skin testing is slightly swollen, red, itchy bumps (wheals). These wheals may be most noticeable during the test. In some people, though, an area of swelling, redness and itching may develop a few hours after the test and persist for as long as a couple of days.

Rarely, allergy skin tests can produce a severe, immediate allergic reaction, so it’s important to have skin tests performed at an office where appropriate emergency equipment and medications are available.