Some people are sensitive to certain particles in the environment and suffer from allergies. While some allergies have minor effects others are quite severe and need hospitalization. An inappropriate immune system activity can lead to allergies.
Allergies are hypersensitivities to certain substances, such as mites in dust, pollen, specific foods or drugs, animal dander, animal hair etc. And the substances to which such an immune response is produced are called allergens. While some allergens affect only the exposed area, others are absorbed or injected into the bloodstream.
In other words an allergy is an exaggerated/inappropriate response of the immune system to certain allergen present in the environment.
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.
There are a variety of tests to diagnose the cause of allergy. The patient is exposed to possible allergens by placing it on the skin or by injecting with very small doses of possible allergens and watching for the reactions such as swelling etc.
If a person presents with acute allergy-like symptoms, the allergen-specific IgE antibody test is done to screen whether a person is allergic to a particular substance.
To quickly reduce the symptoms of allergy drugs like anti-histamine, adrenalin and steroids are used.