How To Read Allergy Skin Tests: All You Need To Know

Avoiding exposure allergens is key to managing any allergy. The first step is finding out what you are allergic to, but this is more difficult than it sounds. Oftentimes, it is unclear what triggers an allergy. For example, a dust allergy can be tricky to identify as dust is everywhere. Other times, it can be hard to find the exact food in your diet that you are allergic to. To identify the allergen — or allergens — you are allergic to, your doctor may give you one or more allergy skin tests. Here’s everything you need to know about them.

Medications Can Affect Allergy Skin Tests

Are you currently on any type of medication? If so, you must make a list of these and present them to your doctor. This step is necessary since there are some medications that can hide allergic reactions, thus, allergy skin test results will not be accurate. In addition, there are some medications that you are taking that may cause an allergic reaction when the allergy skin tests are being done. 

Once your doctor is aware of the medications you are taking, they may ask you to discontinue taking them for 10 consecutive days. For your reference, here is a list of several medications that may cause inaccurate allergy skin test results:

• OTC antihistamines
• Asthma medication omalizumab 
• Prescription antihistamine 
• Tricyclic antidepressants 
• Several heartburn medicines

What Happens During the First Appointment?

Once you have decided to get tested for allergies, the allergologist, a doctor that specializes in allergies, will conduct an examination.

• You will be asked for your medical history. The allergologist will most likely ask if any of your family members also have a history of allergies (e.g. hives, allergic rhinitis, eczema). 
• The allergologist will ask about the symptoms that you are experiencing and their frequency. You may also be asked what your eating habits are and what environment you work in. Knowing this can help to narrow down the cause of your allergies. 
• You will undergo a physical exam. 
• You will undergo allergy skin tests. 

What Happens During Allergy Skin Tests?

After the first appointment, you can actually get tested on the spot, and this applies to both adults and children. After that, results will be shown and you will be diagnosed based on what the results show. The allergologist will then inform you of your diagnosis, tell you what you are allergic to, and provide a treatment plan to manage these allergies. 

There are various tests that you can choose from, and it is imperative that you choose what is right for you with your doctor’s advice.  

During a skin prick test:

• The allergologist will place a few small drops of a specific type of allergen below the surface of the skin. 
• The allergologist will either prick or scratch on the skin after each drop of allergen. 
• A small red bump will appear on the skin after 15 to 20 minutes have passed — if you are allergic to any of the allergens that were applied to your skin. 

During an intradermal test:

• The allergologist will inject a bit of allergen below the surface of the skin. 
• The allergologist will then watch for any allergic reactions on the skin. 

This test is usually done when your previous allergy skin tests show a negative result. An allergist does this test when they also suspect that you are allergic to a specific allergen. 

During a patch test:

• A patch will be placed on the skin, and these patches contain a small amount of a specific type of allergen. 
• This patch should be worn for 48 to 96 hours and after that time period, you must visit the allergist again. 
• The allergist will then remove the patch and check the skin for any allergic reactions. 

During a blood test:

What Do the Results Mean?

Normal results/negative results mean that there were no allergic reactions on the skin after all the skin allergy tests. However, there are rare cases where a person getting a negative result is actually allergic to something. 

A positive test result means that you are allergic to something. The allergist will see this small red bump on the skin called a wheal. If the allergic reaction on the skin is intense then that implies that you are sensitive to that specific allergen that was applied. 

Key Takeaway

The easiest and most accurate way to know if you are allergic to something is to undergo a series of allergy skin tests. Allergy skin tests will also be able to show what type of allergen you are allergic to, so allergists will know what type of treatments to provide to keep allergic reactions at bay. 

Learn more about Skin Allergies here.