Do Dermatologists Do Allergy Testing?

You’re dealing with persistent rashes, itching, or unexplained skin reactions. Could it be an allergy? You might think of an allergist first, but what about a dermatologist? Do they perform allergy testing, or should you see a specialist? The answer isn’t as straightforward as you might think. Knowing who can diagnose your skin-related allergies could make all the difference. So, can a dermatologist help? Let’s dive in.

Visit a dermatologist in the Bronx for allergy testing. Book now!

How Do Dermatologists Test for Allergies?

Dermatologists can perform tests to detect allergies that affect the skin and immune system. Several methods are used to identify the cause of an allergic reaction, such as skin tests or blood tests. These tests help diagnose allergies to airborne substances, foods, animals, and other environmental allergens.

Some conditions can affect the accuracy of allergy tests, so consider the following before undergoing testing:

These tests can be conducted throughout the year if recommendations are followed. Identifying the cause of an allergy is essential to managing symptoms and improving the patient’s quality of life.

1. Initial Evaluation

Before recommending a test, the dermatologist will conduct an initial evaluation to understand the patient’s symptoms and medical history. This step helps determine if the symptoms are related to an allergic reaction and whether a skin test is the best method for diagnosis.

During the Initial Consultation, the Doctor Will Ask About:

• Medical and family history: Whether there is a history of allergies in the family.
• Current symptoms: Frequency, severity, and possible triggers.
• Previous treatments: How the patient has managed symptoms and what medications have been used.

The healthcare provider may also conduct a physical examination to look for visible signs that could help identify the cause of the symptoms.

Providing a detailed medical history and a list of medications will help the dermatologist determine the appropriate test and ensure accurate results.

2. Selection of Allergens

The selection of allergens for allergy tests is based on the patient’s medical history and the prevalence of sensitivity in their environment. Identifying the right allergens helps determine the cause of allergic symptoms and create an effective treatment plan.

Factors That Influence Allergen Selection:

• Environmental factors: Common allergens in the patient’s living area.
• Previous exposure: Substances the patient has encountered frequently.

Conditions That May Require Allergy Testing:

• Hay fever (allergic rhinitis): Nasal congestion, sneezing, watery eyes
• Uncontrolled asthma symptoms: Difficulty breathing, wheezing
• Hives and angioedema: Skin rashes, swelling, welts
• Food allergies: Identified through skin prick testing
• Contact dermatitis: Red, inflamed, or painful skin after contact with an allergen
• Penicillin allergy: The only drug allergy that can be confirmed with a skin test
• Venom allergy: Reaction to insect stings or toxins

Certain tests are not recommended for specific allergens. For example, intradermal testing is not used for food allergies due to a high rate of false positives and potential severe reactions.

3. Skin Tests

Skin tests are used to identify substances that trigger allergic reactions. These tests detect environmental, food, and medication allergies by monitoring skin responses to controlled allergen exposure.

Skin Prick Test: This procedure involves applying a small amount of allergen to the skin and using a needle or lancet to allow absorption.

Procedure:

1. A drop of allergen solution is placed on the skin.
2. The skin is pricked with a needle so the substance contacts the immune system.
3. The reaction is observed for 15 minutes.
4. The size of the raised, red, swollen area (wheal) and surrounding redness is measured.

Considerations:

• May cause temporary itching or irritation; antihistamines or corticosteroid creams can help.
• Not recommended for patients who cannot stop taking antihistamines, as these can alter results.

Intradermal Test: This test involves injecting a small amount of allergen under the skin to evaluate immune response.

Procedure:

1. A small amount of allergen is injected into the skin of the arm.
2. The area is observed for 15 minutes.
3. The skin is examined for redness, swelling, or hives.

Considerations:

• Not used for food allergies due to a high risk of false positives and severe reactions.
• In rare cases, can cause severe allergic reactions, so it should only be done in a controlled medical setting.

Skin tests are an effective way to diagnose allergies. The prick test is the most commonly used and safest, while intradermal testing is reserved for specific cases such as venom or penicillin allergies.

4. Patch Testing

Patch testing is used to detect contact allergies, particularly those causing allergic dermatitis. Unlike other skin tests, this method identifies delayed allergic reactions, which may take several days to develop.

Procedure:

1. The dermatologist applies patches containing 20 to 30 allergen extracts to the skin, typically on the back or arm.
2. The patches remain in place for 48 hours. The patient should avoid showering or excessive sweating during this time.
3. The patches are removed at the doctor’s office.
4. The skin is evaluated again 72 to 96 hours later for signs of an allergic reaction.

Considerations:

• This test does not assess food or respiratory allergies, as it is designed for contact allergies.
• Excessive sweating or moisture can interfere with results.
• Mild itching or irritation in the patch area is normal.

Patch testing is useful for diagnosing contact allergies to metals, fragrances, and preservatives. It provides valuable information to help patients avoid allergens that trigger their symptoms.

5. Blood Tests (When Necessary)

Allergy blood tests are an alternative to skin tests and may be necessary in certain cases. They are used to detect the presence of specific antibodies in the blood in response to allergens, making it possible to identify possible allergies without the need for direct exposure to the suspected substance.

Healthcare professionals may order an allergy blood test when a patient has recurrent allergic symptoms or if severe allergic reactions have occurred in the past.

Symptoms That May Require a Blood Test:

• Nasal congestion: Blocked nose due to inflammation or mucus.
• Sneezing: Common reaction to airborne allergens.
• Itchy eyes: Irritation and excessive tearing.
• Hives: Red, raised skin welts.
• Diarrhea: Digestive issues from food allergies.
• Vomiting: Reaction to certain foods or medications.
• Shortness of breath: Difficulty breathing.
• Coughing and wheezing: Signs of respiratory allergies or asthma.

Allergy Blood Test Procedure

Unlike skin testing, blood testing does not require fasting or withholding medication. It is performed by a conventional blood draw, after which the sample is analyzed in a laboratory for the presence of specific IgE antibodies that indicate sensitization to certain allergens.

They are used in cases of severe allergic reactions, when there are skin conditions that preclude skin testing or when previous results have been inconclusive. Thanks to their safety and accuracy, blood tests help to confirm allergies and develop personalized management strategies for each patient.

How to Proceed After Your Dermatologist’s Allergy Test

After receiving test results, the next step is to manage the allergy and reduce exposure to triggers. Avoiding the allergen may involve checking product labels, changing habits, or finding medication alternatives.

Medication can help control symptoms. Depending on severity, the doctor may prescribe antihistamines to reduce itching and inflammation or recommend fragrance-free, alcohol-free moisturizers to protect the skin. Following the prescribed treatment prevents severe reactions and improves the patient’s comfort.

In some cases, allergy immunotherapy may be an option. If symptoms persist or a severe reaction occurs, contacting a doctor immediately or calling emergency services is essential. A personalized management plan based on test results can help patients maintain better control over their allergies.

Sources:

• Warshaw, E. M., & Nelson, D. (2002). Prevalence of patch testing and methodology of dermatologists in the US: results of a cross-sectional survey. American Journal of Contact Dermatitis, 13(2), 53-58.