Which type of hypersensitivity reaction is involved in allergic rhinitis?

Allergic rhinitis is primarily a Type I hypersensitivity reaction, which involves an immediate response by the immune system to environmental allergens, such as pollen, dust mites, or animal dander. In this type of reaction, exposure to an allergen leads to the activation of IgE antibodies, which bind to mast cells and basophils. When the allergen is encountered again, these cells release histamines and other inflammatory mediators, resulting in the symptoms commonly seen in allergic rhinitis, such as sneezing, nasal congestion, and itchy, watery eyes.

This mechanism is characteristic of Type I hypersensitivity, where the reaction occurs quickly after exposure to the allergen, usually within minutes. Due to its rapid onset and association with specific allergens, Type I hypersensitivity is indeed the correct classification for allergic rhinitis, distinguishing it from the other types of hypersensitivities, which have different underlying mechanisms and timeframes of action.