Allergic rhinitis is caused when your immune system overreacts to airborne irritants, known as allergens. Allergens are tiny enough to be inhaled through the nose or mouth. For most people, these allergens are harmless, but for those with hay fever, the immune system mistakenly identifies them as threats.
In response, the immune system releases chemicals, primarily histamine, into your bloodstream. Histamine causes the mucous membranes in your nose, throat, and eyes to become inflamed and itchy as the body attempts to expel the allergen.
Common allergens that trigger allergic rhinitis include:
- Dust mites
- Pollen
- Pet dander
- Mold spores
- Cockroaches’ saliva and waste
- Food allergiesÂ