Allergic asthma is the most common type of asthma. About 90% of kids with childhood asthma have allergies, compared with about 50% of adults with asthma. Inhaling specific substances called allergens (allergy triggers such as pollen, mites, or molds) brings on the asthma symptoms associated with allergic asthma. Nearly everyone with asthma (allergic or nonallergic) gets worse after exercising in cold air or after inhaling any type of smoke, dust, fumes, and sometimes strong smells.
When asthma symptoms appear and are diagnosed in adults older than 20, it is typically known as adult-onset asthma. About half of adults who have asthma also have allergies. Adult-onset asthma also may be the result of commonplace substances in work (called occupational asthma) or home environments, and the asthma symptoms come on suddenly.
A major task of your immune system is to protect you from bacteria and viruses. However, in people with allergies, part of the immune system is too vigilant. It may treat harmless substances -- like cat dander or pollen -- as if they were enemy invaders and attack them (in your nose, lungs, eyes, and under your skin).
When your body encounters an allergen, it stimulates special cells called IgE antibodies. These defensive cells trigger the body's allergic reaction. They cause the release of chemicals like histamine, which result in swelling and inflammation. This creates familiar allergy symptoms like a runny nose, itchy eyes, and sneezing because your body is trying to destroy the allergens.
What Is Allergic Asthma?
If you have allergic asthma, your airways are hypersensitive to the allergens to which you've become sensitized. Once these allergens get into your airways, your immune system overreacts. The muscles around your airways tighten (an effect called bronchospasm). The airways themselves become inflamed and flooded with thick mucus.
Whether you have allergic asthma or nonallergic asthma, the symptoms of asthma are generally the same and may include any or all of the following: