Allergy Tests: Types and Procedures
Generally speaking, allergy tests are medical tests that includes a set of procedures that identify allergies or sensitivities that a patient has towards certain substances.
These tests may be done differently. Some of the most common methods are a prick test or skin allergy tests, blood tests, and a controlled exposure to the problematic substance. Additionally, a medical team can also resort to patch tests.
Lab Tests versus Exposure Tests
Blood tests, or a lab test, are different than the other techniques when it comes to identifying allergies. This is because they only check the substances currently present in the bloodstream.
These tests usually deal with IgE antibodies, or cells that participate in the protection of our body against substances the body registers as “dangerous.”
On the other hand, there are also exposure tests. These include prick tests, patch tests and controlled exposure to the suspected substance. This allows the medical team to check for any allergic reaction.
To identify the allergen, the medical team studies any symptoms the patient might show and then compares them to previous allergic reactions. In the case of exposure to a drug, they may administer it orally, nasally, through the bronchial tubes, etc. It depends on the characteristics of the drug itself.
Allergy Tests for Medications
Generally, a medical team will perform this type of allergy test when the patient has had an allergic reaction for unknown reasons. After all, medications may produce different symptoms depending on their properties.
According to recent studies, all medications may cause adverse reactions in different people. However, there are certain compounds that can cause more frequent hypersensitivity.
For example, some common symptoms of an allergic reaction to medication include:
- General stinging or burning, or a stinging or burning in the area where the medication was administered
- Fever that can vary in intensity
- Tearing and stinging in the eyes
- Inflammation of the area where the medication was applied
- Anaphylaxis or an anaphylactic reaction in the most severe cases
During an allergy test, the medical team can check several types of medications. For each test, specialists will decide on the most suitable medications to administer. In any case, the test will show any allergy or sensitivity.
Also read: 5 Allergic Rhinitis Remedies
Prick or Skin Tests
Prick or skin tests are another common form of allergy tests. Doctors often use these to determine food, animal, or environmental allergies.
Here’s the common procedure:
- First, the medical team disinfects the patient’s skin on the inner forearm with alcohol.
- Next, the medical team injects a small amount of the substance to be tested into the skin.
- Then, they mark the punctured areas and clean the areas of any remaining substances.
- Afterwards, the patient must wait about fifteen minutes to see if any allergic reaction occurs. During these fifteen minutes, the patient cannot scratch, touch, or alter the area where the substances were injected.
These tests are also common ways to determine if there are any food, environmental or animal allergies.
- In this test, the doctor or nurse first disinfects the patient’s back.
- Then, they place patches that contain test substances on the back. The patches slowly release the compound over a 48 hour time period.
- After 48 hours, the patient must return to his or her doctor to have the patches removed and observe any possible allergic reactions below each patch.
Some recommendations for those having a patch test performed include not wetting or scratching the area of the back where the patches are located and avoiding any intense physical activity that can cause sweating, because it may cause the patches to fall off.
The patient should also avoid the use of surgical tape and taking other medications, if possible.
Controlled Exposure Allergy Tests
Doctors generally use this type of test to directly check a patient for an allergy to a specific medication or a patient’s tolerance to similar substances.
However, this method is riskier than the above-mentioned tests. Thus, in these cases, medical specialists carefully asses the benefits and risks when considering this type of test.
Sometimes, the medical team may need to repeat the procedure due to a false negative result. In these cases, specialists will decide on the best test for each situation and communicate these options with the patient.