What is an Allergy?
An allergy is the response of the body’s immune system to a normally harmless substance, such as pollen, food, or house dust mite. The body has an automatic reaction to what it sees as a threat, and while in most people these substances pose no problem, in those with allergies the immune system identifies them as a threat and produces an inappropriate response to them. Allergies are classified into IgE mediated and non-IgE mediated allergies.
Allergies first start when cells in the immune system wrongly identify an everyday, normally harmless, substance as an attacker. In IgE mediated allergies the immune system then begins to produce begins to produce a class of antibodies known as IgE, specific for that particular allergen, which will later alert the fighting cells (mast cells and basophils) within the immune system every time that this substance is encountered. The mast cells bind with the IgE antibodies so that they can identify the allergen next time it comes into contact with the body. This is called sensitisation, and at this stage there are no physical symptoms of an allergy.
Mast cells are present in all the tissue that is in contact with the external environment, such as the skin, nose, eyes, mouth, throat, stomach and gut. The next time that the same allergen is encountered the mast cells identify it as an intruder and produce histamine and other chemicals. It is the release of the histamine and other chemicals and their effect on the body that cause allergic symptoms.
An allergy can therefore cause anything from a runny nose, or itchy eyes and mouth, to skin rash and gastrointestinal symptoms such as abdominal discomfort (‘tummy ache’) and vomiting. Severe allergies can cause breathing problems or a drop in blood pressure. Severe allergic reactions are also known as anaphylaxis, and can be life-threatening.
In prolonged exposure to allergens the immune system also employs additional fighting cells to attack the invading substance. These release chemical substances that cause further discomfort to allergy sufferers and increase the severity of their symptoms.
However, the immune system can still respond to allergens without the production of the IgE antibody. In non-IgE mediated allergies multiple cells may inappropriately react to the presence of an allergen, and can cause many of the same symptoms as IgE mediated allergies.
Symptoms of IgE mediated allergies occur rapidly and soon after exposure to the allergen, whereas in non-IgE mediated allergies symptoms tend to appear much later after contact with the allergen. In these cases it can be much harder to identify which allergen is causing the problem.
Allergy is widespread and affects approximately one in four of the population in the UK at some time in their lives. Each year the numbers are increasing by 5%, with as many as half of all those affected being children.
Allergy Testing: Tips to Remember
If you have an allergy, your body is reacting to something you inhaled, touched or ate. The substances that trigger an allergic reaction are called allergens. Reactions to these allergens range from annoying to life-threatening.
Many people with untreated allergy symptoms aren’t aware of how much better they can feel once their symptoms are properly diagnosed and managed by an allergist / immunologist, often referred to as an allergist.
An allergist is a pediatrician or internist with at least two additional years of specialized training and is the best physician to diagnose and treat allergies and asthma.
What Are the Benefits of Allergy Testing?
Allergy tests, combined with the knowledge of your allergy specialist to interpret them, can give precise information about what you are as well as what you are not allergic to. Allergy testing should always occur along with a physical examination and a discussion about your past and current symptoms.
For instance, if you wheeze when you are at home and don’t know why, you don’t have to get rid of your cat if your allergy testing shows you are allergic to dust mites but not cats. With this information, you and your allergist can develop a treatment plan to manage or even get rid of your symptoms.
Should I Be Tested?
Testing done by an allergist is generally safe and effective for adults and children of all ages. Symptoms which usually prompt the allergist to perform skin testing include:
• Respiratory: itchy eyes, nose or throat; nasal congestion, runny nose, watery eyes, chest congestion, cough or wheezing
• Skin: hives, itchiness or atopic dermatitis
• Abdominal: cramping and diarrhea or constipation consistently after eating certain foods
• Severe reactions to stinging insect stings (other than swelling at the site of the sting)
• Anaphylaxis (an-a-fi-LAK-sis): a serious allergic reaction that affects many parts of the body at the same time
Most symptoms are caused by one or more of these allergens:
• Dust mites (tiny bugs you can’t see) that live in your home
• Proteins from furry pets, which are found in their dander, saliva and urine (it’s actually not their hair)
• Molds in your home or in the air outside
• Tree, grass and weed pollen
• Cockroach body parts and droppings
More serious allergic reactions can be caused by:
• Venom from the stings of bees, wasps, yellow jackets, fire ants and other stinging insects
• Certain foods
• Natural rubber latex
• Certain medications and drugs
Types of Allergy Tests
Different allergens bother different people, so your allergist will determine which test is the best for you.
The allergen extracts or vaccines used in allergy tests performed by allergists meet U.S. Food and Drug Administration (FDA) requirements, making them safe for use.
This type of testing is the most common and is relatively painless. A very small amount of certain allergens is put into your skin by making a small indentation or “prick” on the surface of your skin.
If you have allergies, just a little swelling will occur where the allergen(s) which you are allergic to was introduced. If you are allergic to ragweed pollen but not to cats, only the ragweed allergen will cause a little swelling or itching. The spot where the cat allergen was applied will remain normal.
You don’t have to wait long to find out what is triggering your allergies. Reactions occur within about 15 minutes. And you generally won’t have any other symptoms besides the small hives where the tests were done, which go away within 30 minutes. If your prick skin tests are negative but your physician still suspects you might have allergies, more sensitive intradermal tests will be used in which a small amount of allergen is injected within the skin.
A skin test has to be done in an allergist’s office to minimize the risk of rare side effects.
In a challenge test, a very small amount of an allergen is inhaled or taken by mouth. Challenges are done mostly with potential food or medication allergies, and it is very important that they be supervised by an allergist.
This test involves drawing blood, so results are not available as rapidly as with skin tests. Blood tests are generally used when skin tests might be unsafe or won’t work, such as if you are taking certain medications, or have a skin condition that may interfere with skin testing.
When to Proceed with Caution
There are methods of allergy testing that the American Academy of Allergy, Asthma & Immunology (AAAAI) believes are not useful or effective. These include: immunologlobulin G (IgG) testing, massive allergy screening tests done in supermarkets or drug stores, applied kinesiology (allergy testing through muscle relaxation), cytotoxicity testing, skin titration (Rinkel method), provocative and neutralization (subcutaneous) testing or sublingual provocation.
• Most people with nagging allergy symptoms don’t realize how much better they can feel once their symptoms are properly diagnosed and treated.
• Allergy testing analyzed by an allergist can pinpoint what you are allergic to.
• Testing done by an allergist is generally safe and practically painless.
• Some new forms of testing, such as allergy screenings performed at supermarkets or drug stores, sound good but can actually be harmful.
Feel Better. Live Better.
An allergist / immunologist, often referred to as an allergist, is a pediatrician or internist with at least two additional years of specialized training in the diagnosis and treatment of problems such as allergies, asthma, autoimmune diseases and the evaluation and treatment of patients with recurrent infections, such as immunodeficiency diseases.
The right care can make the difference between suffering with an allergic disease and feeling better. By visiting an allergist, you can expect an accurate diagnosis, a treatment plan that works and educational information to help you manage your disease.
The AAAAI’s Find an Allergist / Immunologist service is a trusted resource to help you find a specialist close to home.