An allergy test is most often performed by an allergist that involves one of three methods, blood test, skin prick test or patch test.
Allergy testing involves performing a skin or blood test to determine what substance, or allergen, may trigger an allergic reaction in a person. An allergy is the body's reaction to certain substances that we ingest, breathe or touch.
Your doctor will begin by taking a thorough account of your medical history. They will also inquire about your work, home and eating habits to determine the source of your allergy. For this, they will recommend a blood test, skin prick test and patch test.
The following are the most common types of allergy tests:
Skin prick test
- A skin allergy test can detect multiple allergens, sometimes up to 50 at once.
- Skin tests are classified into three types: scratch, intradermal and patch tests.
- They include testing for airborne, food-related and contact allergens.
Patch test
- This test is performed on people with dermatitis or eczema and involves special metal discs that contain small amounts of suspected allergens being taped to the back, which the doctor or allergist then checks for allergic reactions after 48 hours.
- You may also perform a patch test at home, especially before trying new skincare or hair care products.
Blood test
- If the individual has extremely sensitive skin, reacts strongly to needle pricks or scratches or has previously experienced an extreme reaction during skin testing, the doctor will most likely recommend a blood test, also known as the ImmunoCAP test, to detect immunoglobulin E antibodies (IgE) that react to major allergens.
Elimination diet
- An elimination diet primarily aids the doctor in determining food allergies.
- It primarily entails temporarily removing certain foods from your diet (elimination phase) and then reintroducing them later (reintroduction phase).
Challenge testing
- Used to screen for food allergies, this is a controlled test in which you consume increasing amounts of the suspected allergen.
- You must do this under strict supervision because medical personnel must be present in event of a severe reaction.
Why is allergic testing done?
Allergy testing is used to determine which substances (allergens) are likely to trigger an allergic reaction. Skin and blood tests are most commonly used.
The skin test can be done to:
- Identify allergens that are inhaled (airborne) such as:
- pollens from trees, shrubs and weeds
- molds
- dust
- feathers and pet dander
- Determine the most likely food allergens (such as eggs, milk, peanuts, nuts, fish, soy, wheat or shellfish).
- Determine whether a person has a drug allergy or is allergic to insect venom.
A blood test may be done instead of a skin test if a person:
- Has hives or another skin condition, such as eczema, that makes skin test results difficult to see.
- Cannot discontinue the use of a medication, such as an antihistamine or a tricyclic antidepressant, that may prevent or reduce an allergic reaction to a substance.
- Has had anaphylaxis (a severe allergic reaction).
Blood tests can help determine which foods a person is likely to be allergic to.
What are the common signs and symptoms of allergies?
Allergies are hypersensitive immune reactions that occur when certain substances come into contact with the body. Allergens are substances that trigger allergic reactions. Food, medicines, insect stings, pollen, dust mites, pet dander and household chemicals are all common allergens. Symptoms of an allergy can vary depending on the type and amount of allergen.
Some common allergy symptoms and signs may include:
Mild allergic reactions are frequently observed. Moderate reactions may make you a little sick, similar to when you have a cold or flu. Anaphylaxis is a severe allergic reaction that causes life threatening symptoms such as:
- Severe itching
- Wheezing and shortness of breath
- Tightness in the throat
- Tingling of the hands, legs or scalp
How are allergies treated?
Although there is no cure for allergies, a positive test result may help your health provider recommend anti-allergy medications, such as:
- Symptom relief (over-the-counter [OTC] medications that may alleviate allergic symptoms)
- Antihistamines
- Decongestants
- Nasal corticosteroids
- Medications that include a decongestant and an antihistamine
- Adrenaline (epinephrine) injections during life-threatening situations
Unfortunately, all drugs, including OTC medications, can have negative side effects and often become ineffective over time if used continuously. If these do not work, immunotherapy may be required to reduce the body's sensitivity to the allergen, which is a long-term treatment that alters the immune system's response to allergens. It entails injecting or administering sublingual tablets, sprays or drops with progressively increasing doses of allergen extracts regularly until you develop immunity to your allergen.
