Allergic rhinitis

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Allergic rhinitis



Allergic rhinitis


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Allergic rhinitis

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phenylephrine for p. 243

type I hypersensitivity p. 110


“Rhin” refers to the nose and “itis” refers to inflammation, so rhinitis is nasal inflammation.

Allergic rhinitis is also called hay fever, and it’s typically caused by allergens like hay, as well as pollen, dust, animal hair, or mold spores.

When the main trigger is pollinating plants, allergic rhinitis will flare up at specific times of the year.

Allergic rhinitis is a type 1 hypersensitivity reaction, which is a type of allergic reaction that starts with exposure to an environmental allergen.

So - let’s say that a bit of pollen enters the nose. It can get picked up by a dendritic cell which is a type of immune cell that gobbles up foreign particles and presents it to a nearby lymphocyte called a T cell.

If the T cell gets activated, it kicks into action, producing cytokines which helps to get other immune cells involved.

The exact type of T cell determines the type of immune response, and in allergic rhinitis there’s a bit of a T cell imbalance.

There are too many T cells that, when activated, stimulate B cells, another group of lymphocytes, to produce IgE antibodies.

Those IgE antibodies get released into the bloodstream and bind to mast cells, which are immune cells in the tissue that carry within themselves a load histamine.

Once bound by IgE the mast cells are “primed”, meaning if pollen enters the body again in the future, those mast cells degranulate and release their histamine into the local tissue.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  5. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  6. "Allergic Rhinitis" New England Journal of Medicine (2015)
  7. "Overview of 'Allergy and allergic diseases: with a view to the future'" British Medical Bulletin (2000)

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