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Allergy Glossary

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Any airborne substance, like pollen or mold spores, that could cause an allergic reaction.


Also called allergy triggers, are substances that could cause an allergic reaction in some people. Common allergens are pollen, dust mites, food and animals.    

Allergic reaction

An allergic reaction is when the body senses a harmful threat (allergens like dust mites, pollen or food) and the immune system starts to produce antibodies as an attempt to protect the body. The antibody produced is called Immunoglobulin E (IgE). When your body comes in contact with an allergen it recognizes, the IgE binds to it and causes cells in your body to release histamine and other substances which cause inflammation and other symptoms - this is an allergic reaction. 

Allergic rhinitis

May be called hay fever, but allergic rhinitis is not just seasonal. It is a reaction to aeroallergens that your body is sensitized to. Symptoms could include a runny and itchy nose, often in combination with itchy, irritated and watery eyes. 

Anaphylaxis (Anaphylactic reaction)

An acute life-threatening, allergic reaction that is most often caused by an exposure to an allergen. A number of substances (allergens) can cause this but the most common are food (peanuts, tree nuts, seafood, milk, eggs and soy), medications and stinging insects. Common symptoms include hives, tingling and itching around the mouth, swelling in the mouth & throat. An anaphylactic reaction requires immediate medical attention and a trip to the emergency department. Because it can get so serious so fast, speedy treatment is incredibly important.    


A protein produced by the immune system to fight disease. In response to an allergic trigger, antibodies tell your cells to release chemicals, like histamine, causing allergy symptoms. Immunoglobulin E (IgE) is an example of an antibody.


A toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies.


A type of medication that blocks the effects of histamine, a chemical released in your body during an allergic reaction.     


Asthma is a chronic (long-term) lung disease that inflames and narrows the airways. Asthma causes recurring periods of wheezing (a whistling sound when you breathe), chest tightness, shortness of breath, and coughing. The coughing often occurs at night or early in the morning.


Atopy refers to the genetic disposition to develop allergic diseases such as allergic rhinitis, asthma and atopic dermatitis (eczema). Atopy is typically associated with heightened immune responses to common allergens, especially inhaled allergens and food allergens.


The system of immune responses of a body against its own healthy cells and tissues. Simply put, autoimmunity means self-immunity and is an often life-long attack on the body, staged by its own immune system.    

Autoimmune Disease

Any disease that results from an irregular immune response. Autoimmune diseases originate from a continual and persistent immune response against the body itself.  

Autoimmune reaction

An autoimmune reaction is when antibodies and immune cells target and attack the body's own tissues. For many autoimmune diseases, the reaction is linked to an encounter with a particular pathogen, chemical, drug, toxin, or hormone  - but the most important factor is genetics.    

Blood test

A test that is used to help diagnose an allergy to a specific substance or substances by measuring the presence of immunoglobulin (IgE) antibodies to suspected allergens present in a blood draw. 

Celiac disease

Celiac disease is an autoimmune disorder of the small intestine. It is a reaction to eating gluten, a protein found in wheat, barley, and rye. 


Also called pinkeye, it’s an inflammation of the clear thin outer layer (conjunctiva) of the eyeball. When small blood vessels in the conjunctiva become inflamed, they’re more visible. This is what causes the whites of your eyes to appear reddish or pink.1 It can be caused by a virus, bacteria, an irritant (like shampoo, smoke or chlorine) or by allergies.    

Contact allergy

Contact allergy is an allergy to skin contact with certain materials, for instance nickel or skin care products.    


This occurs when the proteins in one substance (like pollen) are similar to the proteins found in another substance (like a food) and your immune system views them as the same, which causes an allergic reaction.


A condition in which patches of skin become rough and inflamed, with blisters that cause itching and bleeding.


An injection-based medication used to treat anaphylaxis. Epinephrine typically comes as a single-dose pre-filled auto injector.    


The cause of a disease or condition.

Eye inflammation

An irritation of the outer layer of the eyeball which can occur as a consequence of exposure to allergens or because of a common cold. This is also known as conjunctivitis and often occurs in combination with rhinitis.

Gastric reflux

Also known as acid reflux, which is a chronic condition of mucosal damage caused by stomach acid coming up from the stomach into the esophagus.


Referring to the gastrointestinal tract, namely the esophagus, stomach, small intestine, large intesting and rectum, and the accesory organs of digestion, the liver, gallbladder and pancreas.


The family of proteins in grains that act as a glue to help hold foods together.

Hay fever

Also called allergic rhinitis, occurs during spring and summer, when for example birch and timothy are releasing their airborne pollen which we inhale. Symptoms are swelling of mucous membranes and runny and itchy nose, often in combination with itchy, irritated and watery eyes.


The chemical that is released by the immune system and is involved in causing an allergic reaction.


Increased sensitivity in the airways, often caused by cold, strong scents and tobacco smoke. This often affects asthma patients.


Increased sensitivity to normally harmless substances, which leads to an incorrect response by the immune system. 


An overactive thyroid gland.


An underactive thyroid gland.


Short for Immunoglobulin E (IgE). These are antibodies produced by the immune system as a reaction to an allergen. IgE is measured in blood tests for allergy.

Immune system

The body’s defense system, which works to defend and protect the body from viruses, infections and disease. But if you suffer from allergies, your body’s immune system reacts to certain normally harmless substances. In autoimmune disorders, the immune system causes the body to attack itself.


A procedure for measuring the immunological activity of a blood sample.    

ImmunoCAP™ Specific IgE (sIgE) blood test

A commonly used laboratory test to aid in the diagnosis of people with allergy-like symptoms. This technology offers specific analysis for over 650 allergens that can cause allergies.    


Also called hyposensitization or allergy vaccination is when an allergen that causes a reaction is administered with increasing doses during a span of time, to help a person develop tolerance to that allergen. The idea is that the immune system can be desensitized to specific allergens and that immunotherapy can lead to lessening of allergy symptoms.


An inability to eat a food or take a drug without adverse effects. Examples of intolerance include, lactose intolerance and gluten intolerance.


A substance that causes slight inflammation or other discomfort to the body.


A sugar present in milk and dairy products.    


A legume is a plant or fruit/seed in the family Fabaceae (or Leguminosae). Well-known legumes include alfalfa, clover, peas, beans, lentils, lupin bean, mesquite, carob, soybeans, peanuts, and tamarind.

Localized reaction

A reaction occurring at the point of exposure (e.g. oral itch from eating something).


Poor absorption of food by the small intestine.

Mast cells

These are an important part of the immune system and can be found throughout the body. Inside the mast cells are different chemicals, like histamine, that when released cause inflammation leading to allergic reactions.

Oral Allergy Syndrome (OAS)

This is a reaction triggered by eating certain fruits or vegetables because of cross-reactivity with pollen proteins. Symptoms include irritation and mild swelling of the lips, tongue, palate and throat.

Otitis media

Inflammation of the middle ear, commonly called an ear infection.


A disease-causing organism.


The development of a disease.

Perennial allergy

Also known as indoor allergies. These result from exposure to year round allergens like house dust mites, mold and animal dander.


Being sensitized to two or more allergens.


Inflammation and fluid production in the nose, sinuses and eyes, caused by a virus infection (e.g. the common cold) or by an allergic reaction (e.g. hay fever).

Seasonal allergy

Result from exposure to airborne allergens, such as pollens, that appear only during certain times of the year.


The process by which your body becomes sensitized to an allergen (like pollen or animal dander) —and then allergic—to a particular substance (allergen).

Skin Prick Test (SPT)

A skin prick test involves puncturing or scratching the upper layer of your skin, to introduce a very small amount of a suspected allergen to your immune system. If you are allergic, a reaction similar to a mosquito bite, a wheal will appear, usually within 20 minutes.

Specific IgE

An IgE antibody to a specific substance, for example cat dander.

Specific IgE (sIgE) blood test

Measures the amount of antibodies in the blood (IgE) to a particular allergen, which is an indicator of allergic sensitization. These are tests for hundreds of allergens, such as pollen (e.g. grass, tree, weed), mold, food, and animal dander. An ImmunoCAPTM Specific IgE blood test can help your healthcare professional determine if you are allergic and to what. It is an easy test and can be performed irrespective of age; including babies, skin condition, medication, symptoms, disease activity and pregnancy.2-5

Symptom threshold

Everyone has a different level of IgE antibodies at which they show symptoms. This is known as the symptom threshold. Until the threshold is reached, they are not affected. However, once the threshold is reached, the combination of sensitizations turns into symptoms.6,7

Systemic reaction

A reaction that involves the entire body (e.g. anaphylaxis).


Commonly known as hives, this is a skin condition characterized by red, itchy, raised areas of skin that appear in varying shapes and sizes.

  1. The Mayo Clinic. Diseases and Conditions: Pink eye (conjunctivitis). http://www.mayoclinic.org/diseases-conditions/pink-eye/basics/definition/con-20022732. Accessed October 2017.
  2. Siles RI and Hsieh F. Allergy blood testing: A practical guide for clinicians. Clev Clin J Med. 2011;78:585-92. 
  3. Bonnelykke K, Piper CB, Bisgaard H. Sensitization does not develop in utero. J Allergy Clin Immunol. 2008;121:646-51.
  4. Belhocine W, Ibrahim Z, Grandne V, et al. Total serum tryptase levels are higher in young infants. Pediatr Allergy Immunol. 2011;22:6.
  5. Bacharier LB, Boner A, Carlsen K, et al. Diagnosis and Treatment of asthma in childhood: a PRACTALL consensus report. Allergy. 2008;63:5-34.
  6. Wickman M. When allergies complicate allergies. Allergy. 2005;60(Suppl 79):14–18.
  7. Burbach GJ, Heinzerling LM, Edenharter G, et al. GA2 LEN skin test study II: clinical relevance of inhalant allergen sensitizations in Europe. Allergy. 2009;64:1507-15.