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Allergens, like pollen, are nothing more than foreign plant antigens. When they get released into the air, you can see and hear the result.When allergens first encounter nasal tissue, sneezing is triggered. This is part of the body’s immune defense.

Pollen allergens then encounter the plasma cells in the nose, which respond by producing antibodies. These antibodies attach to mast cells, which are white blood cells containing the chemical histamine. As more antibodies are produced, they cause the mast cells to release histamine, which produces allergy symptoms such as a stuffy and runny nose, sneezing, and watery eyes. These help to remove the invading pollen.

Medications called antihistamines can be used to help relieve severe allergy symptoms.

Review Date 1/23/2022

Updated by: Stuart I. Henochowicz, MD, FACP, Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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