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. Also, there are medicines to help reduce
the reaction to the allergen.