WHAT IS ALLERGY? - RotaryClinic


Alerjik reaksiyon nasıl gerçekleşir?


The word “allergy” which we have been hearing frequently, especially in recent years, is derived from the combination of the words “allos” (foreign) and “ergon” (work). It is used to describe the reaction to any external stimulus.

Indeed, allergy occurs when a person’s immune system reacts to substances that are harmless to most people, resulting in the appearance of symptoms called allergic reactions.


The substances that stimulate a person’s immune system are called allergens. Almost every substance, including pollen, dust mites, animals, various foods, metals, and drugs, can have allergenic properties.

The immune system produces substances called antibodies. When an antigen comes into contact with an antibody, the immune system cells release substances called histamines. Histamine release leads to the appearance of allergic symptoms such as itching, redness, swelling, and various reactions in the body systems.

Allergic conditions can occur in anyone regardless of gender, age, or race. Allergy is mostly genetic. The tendency of a person to develop allergies due to the genetic characteristics they carry is called atopy. These people are referred to as atopic individuals.

Some people may have an allergic constitution despite not having a history of allergies in their family. This is because genetic and environmental factors work together in the development of allergic diseases.


  • Mothers smoking during pregnancy and breastfeeding, not breastfeeding their babies for at least 6 months,
  • Increase in air pollution,
  • Increase in socio-economic status, which is explained by the “hygiene theory”. It is thought that children growing up in hygienic environments become more sensitive to allergens because their defense systems do not develop enough due to encountering fewer microbes,
  • Increased exposure to allergens; for example, the increase in the habit of keeping pets in homes,
  • Changes in dietary habits, an increase in consumption of ready-made, additive-containing foods instead of natural foods,
  • People who are allergic to a substance are generally more likely to be allergic to other substances as well.


In an atopic individual, an immune response process called sensitization occurs when exposed to a specific substance, leading to an allergy. As a result of this exposure, specific antibodies to the antigen are produced, and upon subsequent exposure, the immune system recognizes the antigen and reacts immediately. The sensitization period can last for a few minutes or even for years. Therefore, allergic diseases can occur at any time in the lives of atopic individuals.

Children with atopic constitutions generally have a comfortable and complaint-free first 3-6 months following birth. Allergic symptoms can be seen after six months as common upper respiratory infections and accompanying itchy skin lesions.

In children, after the age of three, allergic bronchitis can recur frequently with nasal congestion, runny nose, and bronchial involvement. The important thing is to distinguish this condition from infections, make an early diagnosis, and start effective treatment.

The severity and symptoms of allergies can vary depending on the individual and the amount of allergen. Allergic rhinitis, which occurs with nasal discharge and itching, allergic dermatitis, which is accompanied by itching and redness of the skin, and allergic conjunctivitis caused by eye reactions are the mildest and most common symptoms seen in allergic individuals. However, it can also cause much more severe reactions such as asthma and anaphylactic shock.

When diagnosing an allergy, the most important step is to thoroughly question the history and genetic predisposition. Many allergic diseases can be diagnosed based solely on the history and supported by other tests. With the development of laboratory technologies, the variety and reliability of allergy tests have also increased. Allergy tests are generally used to diagnose diseases such as respiratory allergies, food, bee, drug, urticaria and angioedema, contact dermatitis, and atopic dermatitis (eczema).

Allergy tests can be divided into two main groups: skin tests and blood tests.

  • Skin tests are based on evaluating the response that occurs when a person is exposed to an allergen at specific doses. The prick (epidermal) test, intradermal test, and patch test are the main allergy skin tests.
  • Blood tests are used when skin tests cannot be applied or are difficult to apply, especially in children and individuals with severe skin reactions. The most commonly used type of blood test measures the level of immunoglobulin E (IgE) antibody, which is an antibody that the body produces in response to specific allergens. The specific IgE antibody test detects allergen-specific antibodies in the blood.