More than 25 million people in the US have asthma, and allergic asthma is the most common type, affecting around 60% of people with asthma. Both allergic and non-allergic asthma have the same symptoms, such as shortness of breath and wheezing.
Having allergic asthma means allergens trigger your asthma symptoms. Allergens cause an allergic reaction because your immune system thinks they are harmful. Your immune system responds by releasing a substance called immunoglobulin E (or IgE). Too much IgE can trigger inflammation (swelling) of the airways in your lungs. This can make it harder for you to breathe and can trigger an asthma attack.