Allergens are foreign substances that can enter the body and cause an allergic reaction in certain people with a hypersensitive response. While most people mount significant immunoglobin E (IgE) responses only as a defense against parasitic infections, some individuals experience a similar response against common environmental antigens, which are then identified as allergic reactions.

 

Allergens can be anywhere, indoors, outdoors, at work, at home, in our food, and in our air, and are typically grouped into the eight major categories described below.

 

  • Includes household pets and other rodents, fowl, and farm animals.
  • Reactions can be based on dander, hair, feathers, or secretions/excretions.
  • Most common drug allergies are those to the penicillins and related drugs.
  • Can cause severe symptoms such as itching, hives, airway obstruction, fainting, and anaphylaxis.
  • Microscopic organisms that feed on skin flakes shed by humans and other animals.
  • Found in bedding, dust, animal dander, and other airborne allergens.
  • Immune system-mediated response to ingested foods.
  • Symptoms may range from mild reactions to anaphylaxis, requiring immediate treatment.
  • A variety of insects may cause an allergic response.
  • The best known, and potentially most harmful, insect allergy is to bees.
  • Airborne allergens that may be present year-round in the home or other indoor environments.
  • May seasonally increase in concentration following rainy or humid periods.
  • The largest group of airborne allergens known to trigger "hay fever".
  • Includes pollens from grasses, weeds, and trees.
  • Allergens encountered in the workplace.
  • Includes farm-related exposure, manufacturing facilities, and healthcare environments.