What Are Late Vs. Early Phases in Asthma?

Asthma is often triggered by allergies through a multi-phase physiologic response to the allergens. The early and late phases of an allergic response together contribute to inflammation of the airways and increased mucus production.

Asthma and Allergies

• An allergic reaction in the airways can cause an increased inflammatory reaction and airway hyperresponsiveness, according to the National Institutes of Health. Both of these are hallmarks of an asthma attack.

Allergic Pattern

• The allergic pattern identifies how repeated exposure to an allergen causes a step-wise reaction in the airways that includes three parts: sensitization, early phase response and late phase response.

Sensitization

• Sensitization is the initial exposure to an allergen. The initial exposure causes your immune system to react by producing histamine and mediators, which are inflammatory substances.

Early Phase

• The early phase response typically occurs within an hour of initial exposure to an allergen. The histamines and mediators cause allergy symptoms such as sneezing, itchy eyes and runny nose. They also cause asthma symptoms such as wheezing, coughing and shortness of breath.

Late Phase

• The late phase response begins anywhere from three to 10 hours after the initial reaction. This response, which can last for as long as 24 hours, prolongs the asthma attack and includes more severe congestion and inflammation than is seen in the initial response.