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Blood Test Vs. Skin Test For Allergies: Which One Should You Get?

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This article is Medically Approved by Dr. Edward Salko

Allergies are sometimes tossed around as simply your body’s reaction to irritants. 

But allergic reactions can range from mild to life-threatening effects. Therefore, they should be taken seriously much like any other critical health condition.

With that being said, diagnosing allergies should be part of your priorities regarding health assessment. There are two methods that doctors either conduct or request in this process: a skin test or blood test.

These two types of allergy testing are the same and interchangeable for some. However, they are actually different from various standpoints. Most of the time, these differences are critical in understanding the severity of your allergies.

How Are Blood Tests and Skin Tests Similar?

An allergy blood test and skin test follow the same principles when it comes to confirming allergic reactions.

Both the blood test and skin test measure the antibodies known as Immunoglobulin E (IgE). The immune system releases the IgEs in response to an allergen. An allergen is any substance often mistakenly identified as a threat by the immune system.

When this happens, allergic reactions range from itching, sneezing, wheezing, swelling, and formation of rashes or hives. The worst is anaphylaxis, where the symptoms are aggravated and be fatal.

While both tests look for IgE, they differ in the area of assessment. For example, a blood test detects IgE in the blood, while a skin test identifies the antibodies on the skin. This particular difference pretty much determines when one test becomes more appropriate than the other.

How Does a Skin Test Work?

A skin prick test is performed on the skin located either on your back or arm. The procedure is performed in your doctor’s office during your appointment. 

Generally, the process is the most common way to diagnose an allergy as it is also the fastest of the two methods.

Your doctor or a nurse pricks your skin and puts a tiny amount of the suspected allergen above the pricked skin. If you are indeed allergic to that substance, you might feel the reaction right away or within 30 minutes. Otherwise, you may not be allergic to that allergen.

If you consider the speed, simplicity, and the fact that the skin prick test is cheaper, it may seem like it’s superior compared to the allergy blood test. 

However, a significant amount of caution is necessary when performing this test.

For one, the skin prick test requires patients to stop taking antihistamines and other anti-allergy medications for days. This may not be possible for some people, especially if the allergic reactions can get severe without the medications. 

Also, there’s a small probability of anaphylaxis during the actual skin test.

Due to these potential effects, an alternative test is necessary.

When Should You Get a Skin Test?

A skin test is recommended during the following conditions:

1.       You want faster results for your allergy test.

A skin test can generate results almost immediately. If not, the longest you’ll wait is between 20 to 30 minutes tops.

2.       You want a more sensitive test.

Allergic reactions happen fast with the skin prick test. This reaction is partly because you will be asked to withdraw from anti-allergy medications for a few days. Nonetheless, the process is guaranteed to be highly sensitive to allergens.

3.       You want a cheaper allergy test.

If you’re looking for ways to save money in allergy testing, then the skin prick test is definitely for you. This is because it’s a bit cheaper than a blood test. However, you will also be glad to know that less costly allergy blood tests are also available.

How Does a Blood Test Work?

An allergy blood test requires you to visit a lab where a medical professional will assist you in the process.

A blood sample is drawn and analyzed, which means you will get the results after several days, unlike with the skin test, where the results are generated right there and then.

Since the specimen is independently analyzed in the lab, you don’t have to risk any severe allergic reactions to an allergen.

With the skin test, one downside in the process is the probability for the patient to develop anaphylaxis while the suspected allergen is placed on the pricked skin. You don’t have to worry about this scenario with a blood test.

Also, there is no need for you to stop taking medications for days.

When Should You Get a Blood Test?

Between the allergy skin test and blood test, the blood test is regarded as the safer method. You can opt for a blood test with the following conditions:

1.       You can’t stop taking antihistamines and anti-allergy medications.

Get the allergy blood test if it is not feasible for you to withdraw from taking anti-allergy medications due to the severity of your allergic reactions. A blood test does not require this step, unlike a skin test.

2.       You have sensitive skin.

In some cases, skin sensitivity is mistaken as an allergic reaction. Therefore, if you are prone to developing hives and rashes due to conditions like dermatographia or eczema, you better choose blood testing over skin testing.

3.       You want a more comprehensive component testing.

One advantage of an allergy blood test is identifying the very substance that triggers an allergic reaction. 

For example, a food allergy blood test can reveal the specific allergen. In some cases, the protein responsible can also be revealed so you can avoid other foods containing the same protein.

Which Is Better for Allergies?

When it comes to allergy testing, it’s safe to say that both skin tests and blood tests are vital in ensuring proper diagnosis. However, one is not better than the other, considering each test addresses specific conditions.

Some people may not be suited for a skin test; hence they can go for a blood test, and vice versa. 

Also, your doctor may order both types of tests depending on the severity and potential allergy type. 

If you’re aiming for 100% accuracy for your confidence, you can also request both tests.

Nevertheless, both allergy tests are known to produce reliable results, which becomes the foundation of managing your allergies.

When to Get Tested for Allergies?

You should secure an allergy test or at least a consultation with your doctor if you experience the following symptoms common to different types of allergies:

  • Sneezing
  • Shortness of breath
  • Tightness in the throat
  • Trouble speaking
  • Pain in the chest
  • Itchy or clogged nose
  • Skin itching with red rashes
  • Watery eyes and redness
  • Swelling in specific areas (lips, eyes, tongue)
  • Abdominal pain
  • Vomiting or nausea
  • Diarrhea

Don’t forget to tell your doctor if you can observe these symptoms after eating a particular food or exposure to a specific substance. It will speed up the diagnosis as your doctor will narrow down the potential allergens.

The Bottom Line

Identifying the correct allergy is a critical step in alleviating the discomfort of your immune system reaction.

Your doctor can perform a skin prick test or order an allergy blood test depending on your health condition and sensitivity to the test.

To ensure that you are getting the appropriate test, provide your doctor with vital information such as the severity of your allergic reactions and skin conditions you were diagnosed with.

Your priority should always be your safety, and surely, this is also the first thing your doctor will consider.

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