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The word allergy is derived from the Greek, allos ‘the other’ and ergon ‘action’ which is to mean a state of the organism, of the body, with differences in its reactivity. Allergic conditions are well spread and on the rise in the world nowadays. In the developed world, 15-20% of the population suffers from some form of an allergic condition. 80% of the population will undergo at some stage in life, an allergic reaction/condition. 25-30% of the younger population suffers from allergic conditions, and the frequency of occurrences is lower in mountainous populations. Allergic conditions also affect women in greater degrees than men.

Allergic conditions are not localized to a single organ. They may affect different organs, and thus affect several organ systems simultaneously.

What are allergies?

Allergy is the term used to define the immunological sensitivity of an individual towards an allergen (an irritating substance which causes  allergies). This may come as a consequence of:

  1. The inhalation of allergens.
  2. Consuming food which may contain allergens.

Upon entry into the organism, they cause a cascade of chemical reactions which lead to the appearance of allergic symptoms.

  • Sneezing
  • Runny, inflamed nose
  • Itchiness in the eyes
  • Teary, red eyes
  • Coughing
  • Itchiness of the roof of the mouth
  • Bronchial asthma symptoms

Allergies may emerge in the very first months of one’s life. If one of the parents of a child suffer from an allergy, the child has a 40% chance of developing an allergy, and if both parents suffer from an allergy the chance increases to 80% chance. An important role in determining the chances one has for developing an allergy is assigned to environmental factors.

Classification of Allergies

  1. Systemic allergic conditions (anaphylactic shock)
  2. Respiratory allergic emergence (allergic rhinitis, sinusitis, tracheitus, nasal polyps, bronchial asthma, allergic pneumopatias)
  3. Allergies which emerge on the skin (atopic dermatitis, contact dermatitis, urticaria, angioedema, fixed erythema)
  4. Allergies emerging in the digestive tract (irritation of the mouth and gums, stomatitis, gingivitis, gastritis, enterocholytis)
  5. Allergies emerging in the blood (cytopenia, hemolytic anemia)
  6. Vascular emergences (erythema nodosum vasculitis)
  7. Ocular emergences (conjunctivitis, keratitis, uveitis)
  8. Renal emergences (urethritis, cystitis, prostatitis)
  9. Neurological emergences (migraine)


There are two types of allergies: infra-clinical, and clinical. Infra-clinical when only biological signs can be observes (elevated IGE), clinical when clinical signs can be observed (runny nose, inflammation etc).

Atopic Individual

Individuals predisposed to allergic conditions are also referred to as atopic individuals (the allergen is introduced into the body from the external environment). This can be verified through scratch tests with allergens which are performed on the skin:

  • pollens
  • dust
  • domestic animals
  • fungi

Medically Reviewed by a doctor on 22 Aug 2017
Medical Author: Dr. med. Diana Hysi