Home > Glossary

Glossary of Allergy Related Terms

  • Adrenaline – Emergency treatment for anaphylaxis, administered by intra muscular injection.
  • Allergen - A substance, which can cause an allergic reaction.
  • Allergenic – A substance (such as a food or pollen), that has the capacity to induce allergy.
  • Allergy - An immune system response to a foreign substance that is harmless to most people.
  • Allergic Reaction - An adverse reaction involving the immune system, caused by inhaling, swallowing, or touching a substance to which a person is sensitive.  It can also follow injections of medicines, insect stings, or insect bites.
  • Allergic Rhinitis  - An allergic reaction affecting the lining of the nose and the eyes caused by inhaling airborne allergens such as dust mite, pollens or animal dander and also by eating certain foods.  Symptoms may include itching, sneezing, blocked nose, runny nose, and itchy/watery eyes.  
  • Allergist – Consultant in allergic diseases
  • Anaphylaxis – The most severe type of allergic reaction involving many organs in the body.  Onset of symptoms are immediate often affecting the breathing, and may be fatal if not treated immediately.
  • Antibodies - Substances produced by the body to protect itself against infection.  Immunoglobulin E antibodies (IgE) are produced by the body in an allergic reaction.
  • Antihistamines – Medications used to treat allergic reactions by blocking the action of histamine in the body.
  • Angiodema – A swelling of the deeper layers of the skin, usually occurring in soft tissues such as the eyes, lips, and tongue.
  • Atopy – The genetic tendency to develop certain allergies.
  • Bacteriostatic – The ability to inhibite the growth or reproduction of bacteria.
  • Bronchodilator - Medication, which relaxes airway, muscles and widens the air passages.  Used in treating asthma.
  • Contact Dermatitis - An inflammation of the skin (blistered red, itchy and often weeping) which is usually caused by contact with chemicals found in cosmetics, perfume, jewellery and clothing as well as some plants.
  • Desensitisation - Usually referred to as allergen immunotherapy
  • Coeliac Disease – autoimmune disorder of the small intestine.
  • Colic - Spasm of the colon.
  • Dander – Tiny flakes of skin, shed by animals.
  • De-Nature – Permanent alteration of proteins found in allergens rendering them non- allergenic.
  • Dermatologist – consultant specialising in skin problems.
  • Dust Mite - A small mite invisible to the naked eye.  Widely distributed in homes. It is a major cause of asthma & allergic rhinitis.
  • ENT – Ear Nose & Throat.
  • Epigenetics – The effects of environmental factors on the genetic code.
  • Elimination diet – Systematic removal of a food group from the diet to assess causes of food intolerance.
  • Eczema - An inflammation of the skin causing reddening, itching, swelling, and weeping (also known as atopic dermatitis).
  • Eosinophils - A type of white blood cell that circulates in the blood.  They attack tissues at the site of an allergic reaction causing damage.
  • Food/Symptoms Diary – A record of all foods, drinks, & medications consumed, to help identify reactions.
  • Food Intolerance - An adverse reaction by the body to ingested foods or chemicals not involving the immune system. 
  • Food Allergy - An adverse reaction to specific foods such as peanuts, tree nuts, shellfish, egg, and milk that involves the immune system.
  • FPIES - Food Protein Induced Enterocolitis.  An allergic reaction to a food which causes inflammation of the small and large intestine. Differs from a normal food allergy because it is usually a delayed reaction, symptoms are normally limited to the gut (there is no skin rash or swelling).  It is not caused by IgE antibodies and it is not associated with anaphylaxis, so adrenaline is NOT used to treat the reaction
  • Freon Effect – reaction caused by the cold aerosol hitting the back of the throat when inhalers are used, this can be avoided by using a spacer device.
  • Gastroenterologist – consultant specialising in gut related conditions.
  • Gluten – a type of protein found in most grains, such as Wheat, Rye, Barley & Oats
  • Hay Fever - Sneezing watery discharge and itching of the nose and eyes caused by the pollen of grasses and other plants, occurring from spring through to the summer and autumn.  (Allergic rhinitis).
  • Histamine – A substance occurring in mast cells in the body.  In an allergic reaction, it is one of the chemicals released, which causes the symptoms of allergy including itching, sneezing, wheezing, and runny nose and eyes.
  • Hives – Looks like nettle rash, large red raised lumps with a white area in the middle (Urticaria)
  • Idiopathic – Unknown trigger for an allergic response
  • IgE - Immunoglobulin E, a class of antibody associated with the allergic response.
  • IgG – Immunoglobulin G  a class of antibody produced whenever we eat food
  • Immunotherapy - A series of injections, sublingual drops or tablets, that are administered which contain the allergen such as bee venom, pollen, dust mite, or animal dander to which the patient is allergic.  At first the amount given is a low dose, and then the amount is increased at regular intervals, over a period.  Allergen immunotherapy alters the way in which the immune system reacts to allergens, by switching off allergy.
  • Leukocytoxic Test – Scientifically unproven test where white blood cells are mixed with an allergen and are observed under a microscope for a change in shape, supposedly identifying an allergy.
  • Mast Cells - Specialised cells that lie just beneath the surface of the skin and the lining of the nose.  They contain histamine and other chemicals, which cause allergic symptoms.
  • NASG – The National Allergy Strategy Group.  Allergy Campaigning Group. ( See Useful Organisations)
  • Paediatric Allergist – Consultant specialising in children’s allergies
  • Perennial Allergic Rhinitis - Allergic symptoms affecting the nose and eyes the same as hayfever but occurring throughout the year, usually caused by airborne allergens such as dust mite, animal dander, and mould (see allergic rhinitis).
  • Pollen - The pollen grain is a tiny particle carried by insects or wind to fertilise the female flower.  Breathing in pollen causes allergic rhinitis (hay fever) and asthma in some people.
  • Polymorphic light eruption – Allergic reaction to the sun, caused by UVA & UVB rays, causing an itchy rash on the body
  • Rhinitis – Irritation and inflammation of the mucus membrane inside the nose.
  • Sensitisation – Caused when the body repeatedly is exposed to an allergen in the environment leading to the production of IgE antibodies.
  • Sinusitis – Inflammation of the sinuses, which are air cavities, connected to the nasal passages.  If the lining of the sinuses becomes inflamed and infected.
  • Skin Prick Test - A test to identify reactions to allergens.  A positive test is one where a raised itchy lump (wheal) surrounded by a flat red area (flare) develops within 15-20 minutes.
  • Specific IgE Test - A blood test for allergen specific Immunoglobulin E (IgE) antibodies that identifies reactions to specific allergens such as dust mite, pollen, animal dander, moulds, foods and some insect venoms- also referred to as allergen specific IgE tests.
  • Systemic – Reaction involving the body as a whole.
  • Urticaria – The medical word for hives, which are itchy, raised lumps that can vary in position from hour to hour or day to day.
  • Weals - A raised whitish itchy lump, which occurs after skin, prick test or after contact with an allergen and is a term also used to describe the individual lump seen in hives.
  • Vernal Keratoconjunctivitis (VKC) - Is a chronic form of  bilateral conjunctivitis found in individuals predisposed to allergy.