Test for Allergy Diseases

Frequently Asked Question

Q. What are Allergies?

Allergies occur when the body responds to a foreign protein. Usually, these proteins, known as allergens, are not harmful. However the bidy respond can be different for everyone. Some people might just feel a bit uncomfortable, while others could have a really serious emergency called anaphylaxis, which needs quick attention. 

Allergic Reaction: An allergic reaction is the way the body responds to an allergen. When someone has allergies, the first time they encounter a specific allergen, their body responds by making immunoglobulin E (IgE). The immune system creates antibodies, and these antibodies form IgE in response to the allergen. 

Q. What are the Symptoms of Allergies? 

Symptoms of allergies, which vary based on the substance, can impact the breathing passages, sinuses, nose, skin, and digestive system. 

Hay fever, also called allergic rhinitis, can cause:

• Sneezing
• Itching of the nose and eyes
• Runny, stuffy nose
• Watery, red or swollen eyes (conjunctivitis) 

A food allergy can cause:

• Tingling in the mouth
• Swelling of the lips, tongue, face or throat
• Hives
• Anaphylaxis 

An insect sting allergy can cause:

• A large area of swelling (edema) at the sting site
• Itching or hives all over the body
• Cough, chest tightness, wheezing or shortness of breath
• Anaphylaxis 

A drug allergy can cause:

• Hives
• Itchy skin
• Rash
• Facial swelling
• Wheezing
• Anaphylaxis 

Atopic dermatitis, an allergic skin condition also called eczema, can cause skin to:

• Itch
• Reddening
• Flake or peel 

Q. What are the causes of Allergies? 

Allergies begin when the body's immune system confuses a harmless substance with a foreign invader. If the person is exposed to the allergen again, these antibodies release various immune system chemicals, like histamine that causes allergy symptoms. 

Common Allergies Triggers Include:

• Airborne allergens, such as pollen, animal dander, dust mites and mold.
• Certain foods, like peanuts, tree nuts, wheat, soy, fish, shellfish, eggs and milk.
• Insect stings, such as from a bee or wasp.
• Medications, particularly penicillin or penicillin-based antibiotics.
• Latex or other substances which can cause allergic skin reactions. 

Q. What Tests are Done to Diagnose Allergies? 

There are two major types of allergy tests: 

Skin Allergy Tests 

Skin allergy tests are a popular method to test patients for allergic reactions. There are three types of skin allergy tests. 

1. Skin prick test 

This is also known as the scratch test, where the suspected allergen is placed on the back or forearm, and the site is pricked so that the allergen enters the body system. 

The doctor then observes the skin area closely for any reactions. The test is done for multiple suspected allergens at once. In such cases, the procedure is carried out on multiple skin points using the different suspected allergens. 

It is important to note that this test isn’t solely for testing skin allergies. If one suspects a food allergy, a skin prick test can also be used for food allergy testing. The doctor introduces a liquid that contains protein from the suspected food into the body through a prick. If one is allergic to food, there will be reactions at the test site. 

2. Intradermal test 

In the intradermal test, doctors inject a small amount of the suspected allergen just under the skin, and the skin surface is observed for a few minutes for reactions. 

Intradermal injections are mainly administered on the forearm, upper arm, or back. A positive test will result in swelling, redness, or an itch. This test is mainly used for testing penicillin and insect bite allergies. 

3. Patch test 

A patch test is another method of allergy testing involving the skin that is effective in identifying the causes of the allergy. 

It does not involve needles. Instead, a patch embedded with several suspected allergens is attached to the skin. The person is required to wear the patch for up to 48 hours, and during this time it is suggested to avoid bathing or activities that will make a person sweat. 

At the end of the 48 hours, the person should visit the doctor; the doctor then removes it and checks the results. 

With a patch test, one can determine which skin allergy types they have. If a person reacts to any of the tested substances, that is the allergen, and they must avoid it. 

Blood Allergy Tests 

When a person has an allergy, the body produces a high level of immunoglobulin E (IgE), an antibody. Blood allergy tests look for these antibodies in the blood to identify allergies. Blood Allergy Tests are of Two Types: 

1. Total IgE test:

In the total IgE test, the total amount of IgE in the blood is examined. It does not show the type of IgE present or the type of allergy a person has.

2. Specific IgE test:

This test measures the amount of IgE created in response to a particular allergen. There is a specific IgE test for each allergen.