Allergic asthma is an overreaction of the immune system to a substance (allergen) that results in symptoms of an asthma attack: difficulty breathing, wheezing, chest tightness, and coughing. Allergens that can cause allergic asthma attacks include pollen, mold, animal dander, dust mites, cockroaches, and certain chemicals.
An attack may occur from a few minutes to an hour after exposure to an allergen or as long as 4 to 12 hours later. Controlling a person's exposure to substances that trigger allergic asthma attacks may prevent the attacks or help make them less severe. In addition, there are medications to help reduce the reaction to the allergen.
WebMD Medical Reference from Healthwise