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, mould, 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.