What Is Allergy Skin Testing? How It Works and What to Expect


How to read allergy skin test results?

To read allergy skin test results, your doctor will observe the skin's response. Positive reactions appear as raised, red bumps called wheals, surrounded by redness known as flares. The size of the wheal and flare is measured, and a larger reaction implies a stronger allergy. These observations inform the allergy severity.

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A skin test for allergies is a way of diagnosing what allergens you’re allergic to. Taking an allergy test can help you find out exactly what's causing your body to overreact and help you find an effective treatment plan. Continue reading to find out what skin prick allergy tests are, how to prepare for a skin test, what the results mean, and the best alternative methods of allergy testing.

Who Should Get Allergy Tested?

Allergy testing is recommended for anyone who has consistent, recurring symptoms that point toward an allergic reaction. The symptoms could range from sneezing, congestion, postnasal drip, hives, itching, redness, and swelling to more serious ones like difficulty breathing, tightness in the chest, or dizziness.

While these symptoms may appear at different times and levels of intensity, a recurring pattern signifies an underlying allergy that needs identification. You should consider getting an allergy test if you've noticed a consistent flare-up of symptoms when you're exposed to specific environments or substances.

Those with a family history of allergies or atopic diseases such as asthma, eczema, or hay fever are also prime candidates for skin allergy testing. Genetics can play a significant role in allergic responses, and if your immediate family members suffer from allergies, it's a good idea to get tested.

What Is Skin Prick Testing?

Skin prick testing, also known as a scratch test, is a diagnostic tool utilized in allergy medicine. It is designed to identify whether a person has specific allergic sensitivities, especially to environmental allergens like dust, pollen, mold, pet dander, or certain foods.

The skin prick test involves pricking the skin with a small, sterile lancet, to introduce a tiny amount of suspected allergen. The test capitalizes on the body's immune response to these allergens; if you are allergic, your immune system will respond by releasing chemicals that cause allergy symptoms.

This test is key in allergy diagnosis due to its sensitivity and specificity. It's a valuable tool because it can provide a detailed picture of a person's allergies, which is essential in creating a personalized and effective treatment plan. It's not only used to identify the specific substances to which a person is allergic, but it can also give an indication of the severity of the allergies based on the skin's response. It's worth noting that the skin prick test isn't suitable for everyone, such as people with severe skin conditions or those prone to anaphylaxis.

What Allergies Does It Test For?

The scratch tests are capable of identifying as many as 50 different allergies at the same time. They're simple yet informative tests that play a crucial role in mapping out allergies. They allow healthcare professionals to develop tailored treatment plans, enhancing your ability to manage allergies effectively.

  • Environmental allergens: These are typically inhaled and can cause respiratory or skin symptoms. They encompass a broad range of substances like dust mites, molds, pollen from trees, grasses, weeds, and pet dander from animals like cats and dogs.
  • Food allergens: The skin prick test can identify many types of food allergies. Common ones include milk, eggs, peanuts, tree nuts (such as walnuts, almonds, and cashews), soy, wheat, fish, and shellfish.
  • Insect allergens: This test is useful for diagnosing allergies to insect stings from bees, wasps, or hornets, and to bites from insects like mosquitoes. It can also detect allergies to cockroaches.
  • Medication allergens: While less common, skin prick tests can be used to test for medication allergies. Some people have drug allergies, like penicillin allergies.
  • Latex allergy: It can also test for a latex allergy, which is important for people who need to wear latex gloves for work or who may come into contact with latex during medical procedures.

What Happens During A Skin Test?

Before starting the allergy skin tests, your allergist will review your medical history. This provides crucial context about potential allergens and your body's previous reactions. To start the skin prick test, your allergist will cleanse a section of your skin, usually on the forearm or back.

Using a thin needle, they'll lightly prick your skin, introducing minute amounts of various suspected allergens. Once the allergens are applied, you'll wait about 15 to 20 minutes. If you're allergic to one of the substances, your body's immune response will cause a red, itchy bump known as a wheal to appear on your skin with surrounding redness called flares. The allergist will then measure these reactions, with larger bumps often indicating more severe allergies.

How to Schedule an Allergy Test?

Scheduling an allergy test is straightforward. Start by consulting with your primary care physician, who can provide a referral to an allergist if necessary. Once you have a referral, contact the allergist's office to make an appointment.

Discussing your current medications with both doctors is important, as some may need to be temporarily discontinued to ensure accurate test results. Be sure to describe your symptoms accurately and thoroughly to assist the allergist in determining the most suitable allergy test for you. Alternatively, there are now online platforms where you can book an appointment directly with a certified allergist.

How to Prepare for a Skin Prick Test?

Preparing for a skin prick test involves discussing your medications with your allergist, ensuring your skin is clear, and understanding the allergy testing process. The aim is to ensure accurate results and minimize risks. Here are the key steps to follow before your appointment:

  • Discuss your medications: Certain medications can interfere with allergy skin tests, so discuss your current medications with your allergist. Antihistamines, for example, can suppress allergic reactions and should be stopped several days before the test. Other medications, such as heartburn medications and antidepressants, can also affect the results.
  • Opt for comfortable clothes: The test involves needle pricks, typically performed on the upper arm or back. Dress in clothing that easily exposes this area, making the allergy testing process more convenient and comfortable.
  • Keep your skin clear: For accurate results, the test site—usually your back or forearm—needs to be free from dermatitis, eczema, or other significant skin conditions. If you have a skin condition, your allergist may recommend a different type of test.
  • Inform your doctor about your health conditions: If you have cardiovascular disease, severe allergic asthma, or other serious health conditions, make sure your allergist knows. In rare cases, scratch tests can trigger severe allergic reactions, so your doctor will want to ensure the benefits outweigh the risks.

How Long Does Skin Prick Testing Take?

Allergy skin testing is a relatively quick procedure, usually taking around 20 to 30 minutes for the allergens to react with your skin. If you're allergic, your skin will develop a raised, itchy bump. If you're not, you'll get a negative allergy skin test result.

After this reaction time, your allergist will spend a few more minutes measuring and documenting the reactions to each allergen. So, the total time spent in the office could be around an hour or two. While this test is generally effective, it can be time-consuming and result in uncomfortable and itchy hives.

Do Skin Allergy Tests Hurt?

Skin allergy tests generally cause some discomfort and may hurt depending on how many allergens you’re being tested for. That said, the tiny lancets used in a skin allergy test barely penetrate the skin's surface, and many people describe the sensation as a light prick.

However, if you have a positive reaction to any of the allergens tested, you might experience itchiness or irritation in the test site, similar to a mosquito bite. While the test itself is not considered painful, it's essential to communicate any discomfort or concerns to your allergist during the procedure.

What Do the Results Mean?

The results of allergy skin testing are interpreted based on the size of the wheal and the flare. These responses are compared to your reactions to control substances: a positive control that your skin should react to and a negative control that your skin shouldn't react to.

Your allergist will measure the wheal and flare of each skin reaction and record these measurements on an allergy skin test results chart. Generally, a larger wheal and flare indicate a stronger allergic reaction.

However, interpreting allergy test results isn't as simple as larger equals more severe. The allergist will consider your medical history, symptoms, and other tests, if any, alongside the skin test results. For example, a large wheal to an allergen you've never encountered or eaten (in the case of food allergens) might not be clinically relevant.

How Can You Tell if The Results Are Negative?

Receiving a negative result in a skin prick test is indicated by the absence of a skin reaction. In other words, if your skin doesn't respond with a wheal or any surrounding flares, the test for that specific allergen is considered negative.

This typically means you're not allergic to the tested substance. It's also crucial to note that skin prick tests can sometimes yield false positives or negatives. A false positive is when you react to the skin test but do not have symptoms when exposed to the allergen in everyday life.

A false negative is when you do not react to the skin test but do experience symptoms with exposure to the allergen. Your allergist will discuss these results with you, explaining what they mean in the context of your symptoms and lifestyle, and use them to develop your personalized treatment plan.

Risk Factors and Complications

While skin allergy tests are generally safe, like any medical procedure, they do come with certain risk factors and potential complications. Here are some to consider:

  • False positives or negatives: As mentioned earlier, allergy skin tests can sometimes yield false positives or negatives, which can lead to misinterpretation of the severity of your allergy or even misdiagnosis.
  • Severe allergic reactions: In rare cases, allergy skin tests can cause a whole-body allergic reaction known as anaphylaxis. This can be life-threatening and requires immediate medical attention.
  • Worsening of symptoms: The test could cause a temporary flare-up of allergy symptoms, such as redness, itching, and swelling.
  • Interaction with medications: Certain medications can interfere with the results of skin tests, leading to false results. It's essential to inform your doctor about any medications you are taking.
  • Risk for people with certain conditions: People with certain heart conditions, severe asthma, or those who have experienced anaphylactic reactions may not be suitable candidates for skin tests due to the risk of severe allergic reactions.
  • Impact on skin conditions: For people with skin conditions like eczema or psoriasis, allergy skin tests may worsen their condition or make the results difficult to interpret.

Despite these potential risks, skin testing remains a valuable tool in diagnosing allergies and managing allergic diseases. Your allergist will always weigh these risks against the benefits of getting a clearer understanding of your allergies.

Alternative Methods of Testing

While skin prick testing is a commonly used method for diagnosing allergies, it's not the only option available. Depending on the patient's medical history, skin condition, and specific circumstances, other types of tests may be more appropriate.

Intradermal Test

In an intradermal test, a small amount of allergen is injected into the skin surface with a fine needle. This test is more sensitive than a scratch test and is often used when the allergist suspects an allergy, but the skin prick test is negative. Intradermal testing is more sensitive and can produce more accurate results.

Blood Tests

Blood tests, such as the radioallergosorbent test (RAST) or ImmunoCAP, measure the amount of specific IgE antibodies in your blood that are produced in response to allergens. Blood tests may be used when skin tests can't be done, such as in patients with severe eczema or those who can't stop taking certain medications. Blood testing is also more accurate than scratch tests.

Patch Tests

Patch tests are used to diagnose contact dermatitis, a type of skin allergy caused by touching certain substances. The allergen is applied on a patch, which is then placed on your skin. The patch must stay on for 48 hours, and you'll return to your doctor to have the results read after an additional 24 to 72 hours.

At-Home Allergy Tests

At-home allergy tests offer a convenient alternative to traditional testing methods. Wyndly, for instance, provides an at-home allergy test kit that allows you to take the test in the comfort of your own home. The kit includes everything needed to collect a small blood sample, which is then mailed to a lab for analysis. This can be a good option if you're unable to visit an allergist in person or prefer the convenience of at-home testing.

When to See a Doctor for Allergy Testing

Knowing when to see a doctor for allergy testing can be a vital step in managing your health. Although allergies are not uncommon, persistent or severe allergic reactions need to be evaluated by a professional to prevent complications and enhance the quality of life. Here are some signs:

  • Persistent symptoms: If you frequently experience allergy symptoms like sneezing, runny nose, itchy eyes, or skin rashes, it may be time to get tested.
  • Unsuccessful OTC treatment: Over-the-counter (OTC) allergy medications aren't alleviating your symptoms.
  • Severe allergic reactions: You've experienced severe reactions, such as difficulty breathing or anaphylaxis.
  • Reduced quality of life: Your allergy symptoms are significantly impacting your daily activities or causing you to avoid certain situations or environments.

Take Our Allergy Assessment

If you're struggling with allergies and seeking a convenient and long-term solution, consider Wyndly's services. Wyndly offers at-home allergy tests and personalized treatment plans to help you manage your allergies effectively. Take control of your health and take the first step towards an allergy-free life. Start with our quick and easy allergy assessment test to begin the journey toward lifelong relief.

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