Class 12 Biology Human Health Disease Allergy


The exaggerated response of the immune system to certain antigens present in the environment is called allergy.

The substances to which immune response is produced are called allergens.

Common examples of allergens are mites in dust, pollens, animal dander etc.

Allergy is due to the release of chemicals like histamine and serotonin from the mast cells.

The antibodies produced to these are of IgE type.

Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing.

The patient is diagnosed by injecting or exposing the patient to very small doses of allergens.

Drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy.

Fig. allergy  

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