Overview of allergy test
An allergy test is a diagnostic tool employed by a specialist to find out if you are reactive to a substance. The substance that has been tested for is referred to as an allergen. You will be exposed to a very small portion of the allergen. After the exposure to the potential allergen, the part of the skin exposed is closely observed for any reaction. If there are any reactions, they will be noted and recorded.
The body has a system that is used for defense against substances that look like a threat to it. This system is the immune system. The immune system swings into action when a seemingly dangerous substance (allergen) finds its way into the body. What the immune system perceives as a threat isn’t a threat in the real sense.
Pollen, for instance, can make the immune system overreact by making you have watery and itchy eyes. It can also result in you developing a runny nose. Blocked sinuses and sneezing are other consequences of a reaction to pollen.
Types of allergens
Three different types of allergens can cause allergies:
1. Inhaled allergens: Inhaled allergens can only cause an allergic reaction when they get into the body especially the respiratory tract. They can make the throat swell. Pollen is the most common inhaled allergen.
2. Ingested allergens: They are those that can be found in food e.g. seafood, peanuts, and soy.
3. Contact allergens: They are those allergens that cause reactions when they come in contact with your skin. Contact allergens are characterized by skin rashes and itchiness. A common example of a contact allergen is poison ivy.
Why an allergy test is performed
About 50 million US residents are affected by one form of allergies or the other based on reports from the American College of Allergy, Asthma, and Immunology. Inhaled allergens are the most common type of allergens.
More than 40% of people who live in the US suffer from hay fever and seasonal allergies. Both are caused by pollens.
250, 000 deaths are recorded every year from asthma attacks. This figure was submitted by the World Allergy Organization.
An allergy test can reveal the specific substance i.e. mold, pollen, etc. that is making the allergy occur.
With medications and good care of yourself, allergies can be managed.
How to prepare for an allergy test
Before an allergy test is conducted on you, your doctor will investigate your family background, lifestyle, and more. You will likely be told to stop taking medications that can negatively influence the test result. Such medications include:
- famotidine (Pepcid)
- asthma drug e.g. omalizumab (Xolair)
- benzodiazepines e.g. lorazepam (Ativan), or diazepam (Valium)
- tricyclic antidepressants e.g. amitriptyline (Elavil)
How an allergy test is performed
To perform an allergy test, two things can be used. These two things are your blood or your skin. The potential allergen can be introduced into the blood or on the skin. Also, an allergy test might require that you eliminate some meals from your diet if your doctor perceives strongly that you have a food allergy.
The risks of an allergy test
An allergy test can make you experience itchy skin with red patches. Mild swelling of the skin can also be seen. Small bumps can also be seen on the skin. Within a couple of hours and sometimes days, symptoms can clear up. Topical steroids can facilitate the clearing up of the symptoms.
Mild topical steroid creams can alleviate these symptoms. Allergy tests can make you develop deadly allergic reactions without delay. Allergy tests are hence best conducted in the doctor’s office where provisions for the arrest of any anaphylaxis (severe reactions) are available. Epinephrine is one medication that is readily used for the treatment of anaphylaxis.
Your doctor should be contacted without a second thought when you find that you are overreacting after an allergy test. You should call 911 when you can’t reach your doctor immediately particularly when you are experiencing serious breathing difficulties, increased heart rate, swollen tongue, and low blood pressure.
The goal of all skin tests is to identify potential allergens. Potential allergens fall into any of these three classes – airborne allergens, contact allergens, and food allergens.
Three tests can be conducted on the skin in order to evaluate possible allergens. They are scratch tests, intradermal tests, and patch tests.
To carry out a scratch test, an allergen mixed in a liquid will be introduced into your skin. Your reaction to the allergen will be watched out for by the doctor.
When localized itchiness, redness, or swelling is experienced at the point where the potential allergen was introduced into your skin, then you are considered to be allergic to that substance.
If your doctor could not conclude on the scratch test, another test called an intradermal test will be conducted on your skin test. What is done in an intradermal test is simple. A very little amount of a potential allergen is injected into your skin particularly into the dermis. The dermis is the part of the skin located just beneath the outer skin layer (epidermis). When the allergen has been successfully introduced into the dermis, reactions will be watched out for by your doctor
Another skin test you should know about is the patch test. A skin patch test uses adhesive patches that contain allergens that are thought to be responsible for your allergy.
These patches are placed on your skin. After some hours, 48 hours to be precise, the place where the patches were placed on your skin will be reviewed. You don’t have to wait in the hospital for this number of hours. You can go home and return when it’s about the 48th hour from the time the patches were placed on your skin. Your skin will be reviewed again after 72 and 96 hours.
Blood tests are usually in the laboratory. The test called immunoCAP is used to detect the presence of IgE in your blood. IgE is an antibody released during an allergen attack. An immunoCAP is preferred by the doctor if he suspects you are going to react to a skin allergy test.
With an elimination diet, your doctor might be able to find out the food that has been causing your allergic reaction. To do this, certain foods will be exempted from your normal diets and then re-added. From your reactions, the food triggering the reaction can be identified and then eliminated from your diet.
After an allergy test
When your allergy trigger has been evaluated by your doctor, a plan of treatment will be designed for you. The plan of treatment will be aimed at helping you get better.