Allergies

Inflammation: Mast cells, eosinophils, and Th2 immune cells release histamine, leukotrienes, and cytokines that swell the airway tissue.
Bronchoconstriction: The smooth muscles surrounding the airways contract sharply, narrowing airflow passages.
Mucus overproduction: Chronic inflammation triggers excess mucus that further blocks breathing.

Subtypes

Asthma
Pollen Allergy (Hay Fever)

Description

A group of conditions where the immune system overreacts to harmless substances (allergens) in the environment, such as pollen, dust mites, pet dander, foods, or insect stings. This overreaction causes symptoms ranging from mild (sneezing, itching) to severe (anaphylaxis). Common allergic conditions include hay fever, food allergies, eczema, and asthma.