How do doctors diagnose allergies?

Types of allergy tests - Healthians
Contributed by – Preksha Buttan

If the cold breeze is making your skin red and itchy and cuddling with a pet is making you sneeze, then don’t consider these signs as something normal or assume that you might be just coming down with a cold. These are actually common symptoms of allergy. In case you don’t already know, allergy can have life-threatening symptoms. So, getting tested for allergies is the wisest option for you to avoid any complications and be more aware about your allergic conditions including ways to manage them. There are various types of tests available that doctors use to diagnose allergies. Wondering what these tests are and which one is the best for you? Let’s find out! 

Before we dive into the type of allergy tests, let us first see what information a doctor requires before making a diagnosis.

 

Information needed to diagnose an allergy

Clinical history – This is where the diagnosis of an allergy begins. Your doctor will ask you various questions about your general health and the symptoms you have while focusing on the allergies and the conditions that coexist with them, such as asthma and eczema.

Family history – Further, your doctor will ask you if any of your close relatives have allergic symptoms or were diagnosed with related conditions.  

Overall physical health – The doctor will also perform a complete physical exam while giving special emphasis to your eyes, ears, nose, throat, chest, and skin.

Allergy tests – To confirm the diagnosis, one or more types of allergy skin tests or blood tests will be performed to determine the exact cause of allergies. 

[Also read – Allergy tests and all the benefits you get from it]

 

Types of allergy tests

Skin test for allergy

Skin test for allergy - Healthians

In the allergy skin test, doctors use extracts or a concentrated liquid form of allergens like pollen, mold, pet dander, dust mites, or food. Once these allergens come into contact with your skin, your body would trigger a response. Based on that, a diagnosis is made. 

 

What happens during a skin test for allergy?

There are three main types of skin tests to diagnose allergies. They are – 

Scratch test – First, the doctor will clean a small area of the skin on your forearm or back with alcohol and make some markings and labels with a pen. Then a drop of the potential allergen will be placed on that part. Next, the outer layer of the skin will be scratched to allow the allergen go a little deeper. This test is also known as a puncture test or prick test.

Intradermal test – In this type of test after cleaning a spot of the skin, the doctor directly injects a small amount of allergen just under the skin.

Patch test – In the patch test, the allergen is put on a patch and then that patch is stuck on the arm or back. 

 

What to expect and how to prepare?

Before the tests, inform your doctor about all the medicines you take, including the over-the-counter products. Some of them can influence your test results, so you’ll be asked to avoid having them before the test. In case, you can’t skip the medicine, your doctor will perform separate tests to determine what effects they can have on your results. You should also not take any medicine that provides relief from the allergic symptoms for a few days before the test. 

Skin tests may make your skin mildly irritated and itchy. But it usually resolves on its own in some time as the amount of allergen used is small. Whole-body reactions are rare. However, if you develop fever, lightheadedness, difficulty in breathing, or widespread rash after the test, inform your doctor immediately.

 

Blood test for allergy

Blood test for allergy - Healthians

When you come in contact with an allergy trigger, your body produces antibodies against it. These antibodies encourage the release of certain chemicals in the body that lead to allergy symptoms. Allergy blood tests aim to detect these antibodies in the blood. Their presence or absence helps the doctor make an appropriate diagnosis. 

One of the most effective blood tests for allergy is called Phadiatop. It uses ImmunoCAP which contains small samples of a wide range of inhalant allergens. To make a diagnosis, the reaction of the blood with the allergens is determined. This test has an accuracy of over 90% and is considered one of the most reliable methods to diagnose allergies.

An allergy blood test is typically used when you – 

  • Cannot stop taking medicines that would interfere with the results.
  • Cannot tolerate many needle scratches required in skin tests for allergy.
  • Have unstable heart condition and uncontrolled asthma.
  • Have severe eczema, dermatitis, psoriasis, and other serious skin issues.
  • Have a history of life-threatening allergic reactions.

[Also read – The ABC of food allergy you need to know]

 

Elimination diet 

Elimination diet - Healthians

An elimination diet is basically a meal plan that aims to cut out certain food or ingredients from your diet to find out what exactly you are allergic to. This diet isn’t about weight loss. You will be simply asked to not eat certain foods that could possibly be the cause of your allergic symptoms. Here, you’ll have to work with your doctor to make sure that you still get all the required nutrients. However, remember this diet is not recommended in case of severe allergic reactions.

 

How does an elimination diet work?

There are two phases in an elimination diet – The elimination phase and the reintroduction phase.

Elimination phase – This is the first phase of the elimination diet where you stop eating suspicious food. Keeping a food diary wherein you note all the food you eat and the way you feel after that is recommended.

Reintroduction phase – This is the phase wherein you reintroduce the problematic food into your diet. You do it slowly and one food at a time. This process helps in finding out the exact food that is a problem for you. You’ll again need to keep a track on your diary of all the food you eat and the way you feel after having them. In case you develop a severe allergic reaction after consuming any problematic food, contact your doctor immediately.

At last, once the food you are allergic to has been pointed out, you stop consuming it for good. 

Based on the results you get in these tests, you can make lifestyle alterations to avoid your triggers and not have symptoms flare-up. This is the best way to live with allergies and stop them from interfering with your life.

 

Get tested for allergies now 
 

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