Allergy:

• The exaggerated response of the immune system to certain antigens present in the environment is called allergy.
•  The substances to which such an immune response is produced are called allergens. For example: dust, pollens, animal dander, etc.
•  Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing.
•  Allergy is due to the release of chemicals like histamine and serotonin from the mast cells. IgE type antibodies are released in its response.
•  The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy.