Allergens (2022)

Allergy is a disorder of the immune system which reacts to a normally harmless foreign substance such as house dust mites, pollens, or certain foods.

In people with allergies, the immune system produces antibodies that identify a particular allergen as harmful following contact, ingestion or even inhalation. The immune system’s reaction can cause inflammation of the skin, sinuses, respiratory airways, or digestive system.

Allergies are a common, chronic, often debilitating condition that often affects the patient’s quality of life and can sometimes even cause anaphylaxis, a fatal reaction.

Allergy diagnosis

The diagnosis of respiratory allergies is based on clinical history, physical examination, allergy tests and specific questions. One of the diagnostic methods used by medical practitioners to identify the triggering allergens in patients is a skin prick test.

Via a prick to the skin, the patient is exposed to the suspected allergen and is monitored. After approximately 20 minutes, the skin is observed for any signs of reaction to one or several of the allergens: redness, swelling, itching.


Allergen immunotherapy

Allergen immunotherapy (AIT) is an allergy treatment designed to treat the underlying cause of the disease as well as have a long-lasting effect on all symptoms. After an accurate diagnosis of the type of allergy and responsible allergens, patients, in line with their healthcare practitioner’s prescription, receive a targeted treatment, available either in sublingual (tablets or solutions) or subcutaneous (injections) form depending on product availability in each country.

Because it treats the root cause, AIT results in immunologic tolerance, i.e., a decrease in the body’s reaction to an allergen. Through the repeated administration of specific allergens to patients, the immune system builds resistance by changing the types and proportions of antibodies (immunoglobulins) and proteins (interleukins) it produces when it is exposed to the allergen, thus reducing symptoms when patients are exposed to the allergen in their environment – even after treatment ends. AIT usually requires 3 to 5 years of treatment1.


Human allergies

Potential allergy symptoms in humans cover a variety of symptoms which can range from mild to severe. If left untreated allergy symptoms can worsen over time.

Symptoms vary from one person to another and according to the allergy and include: psychological symptoms (fatigue, irritability, poor sleep, negative effect on concentration and performance); allergic conjunctivitis with itchy, red and watery eyes; allergic rhinitis with sneezing and blocked or runny nose; swelling and itching in the oral area; suffocation by swelling of the throat and larynx; allergic asthma with dry cough and shortness of breath; skin or digestive discomfort; wheezing; constricted airways in the lungs; severe lowering of blood pressure and shock.


Veterinary allergies

Animals can suffer from many of the same ailments as people. Most allergies in animals fall into three categories: environmental allergies, food allergies, and insect-bite allergies.

Allergies in animals can have a significant impact on quality of life and can strain the relationships between people and their companion animal. Symptoms of potential allergies in companion animals such as dogs, cats and horses (symptoms vary according to species) include: itchiness (excessive scratching, licking, chewing themselves, overgrooming, rubbing against trees, fences, stalls or rolling in the dirt or grass); red, infl amed skin, small scabs or crusts on the body; fur loss; frequent, recurrent ear infections and/or anal gland problems; hives; digestive discomfort; sneezing and runny nose and/or eyes.




Grasses are one of the most common causes of allergies. The pollen released by grass can be carried by the wind over many miles.

Food allergies

The most common food allergies are triggered by milk, egg, peanut, tree nut, soy, wheat, fish and shellfish. While most symptoms from food allergies are mild and limited to skin or digestive discomfort, some people may develop anaphylaxis which can lead to constricted airways in the lungs, severe lowering of blood pressure and shock and suffocation by swelling of the throat and larynx.



Tree pollen is the first seasonal allergy of the year, with some trees releasing pollen in January. Trees that trigger allergies include ash, beech, birch, cedar, elm, mulberry, olive, poplar, willow, etc.

Insect venom

Insect venom stings can cause severe reactions in people with allergies. While some will have only minor reactions to stings, others may have a lifethreatening allergic reaction and go into anaphylactic shock. Venoms responsible for allergic reactions include species from the Hymenoptera order including honey bees, hornets, wasps and yellowjackets.



Weed pollen season occurs from spring to early autumn. Weeds that trigger allergies include mugwort, nettle, lamb’s quarters, ragweed, sage, Russian thistle, etc.



Animals with fur can be a source of allergy. The body reacts to dead fl akes of skin shed by animals. What triggers an allergic reaction isn’t pet fur, but a substance found on the pet’s fur; this allergen is produced by the skin of felines and is also present in their saliva, urine, tears and dander.


Air pollutants

Traffic-related emissions are a significant source of air pollution and can worsen allergic rhinitis symptoms and asthma. Industrial air pollutants and particulates can exacerbate allergic rhinitis and asthma as well as modify the allergenic potential of certain pollens.



Natural rubber latex, the protein in the sap of the Brazilian rubber tree, is found in many consumer goods (balloons, rubber bands, etc.). Latex allergy symptoms may include hives, itching, stuffy or runny nose. It can cause asthma symptoms with diffculty breathing and can result in anaphylaxis.


House dust mites

House dust mites belong to the Arachnida class, which includes spiders and ticks. They measure between 0.2-0.4 mm and are present in all households where they tend to be more numerous in bedding, upholstery, carpets, etc.


Mould, mildew

Fungi can be found both indoors in damp areas (bathroom, kitchen, etc.) and outdoors (fallen leaves, compost, grasses, etc.). The spores produced by the fungi are released by wind and dew.


1. Marogna M. et al., Long-lasting effects of sublingual immunotherapy according to its duration: A 15-year study. J Allergy Clin Immunology, 2010)