People with asthma have trouble breathing because the tubes that carry air to and from the lungs (that is, the airways) become inflamed. Inflammation causes mucus to build up in these tubes, cutting down on the space available to move air. Inflammation also stimulates the muscles around these tubes to contract, or go into spasm (bronchospasm), in reaction to minor irritations. Bronchospasm further narrows the tubes and cuts down the airflow.
For many people, inflammation in the lungs is an allergic reaction. Although the trigger for inflammation in the lungs can be different for different people, some allergy triggers are very common, shared by many people who have asthma.
Allergy reactions occur in most people who have asthma. When allergy occurs, immune cells within the lungs and airways overreact to foreign substances in the air, such as cat hair, mold, or deposits left by dust mites. Many people with asthma benefit from seeing an allergy specialist who can help manage their condition.
Once the airways are inflamed, minor irritation can make the airway muscles spasm. Inflamed airways are sensitive to irritants in the air that are not true allergens, such as pollution, cigarette smoke, or sulfite gases (gases from fermentation of some drinks or foods). For many asthmatics cold air can constrict the airways, and this is the cause of exercise-induced asthma. (When you breathe hard during exercise, your nose and throat don't have a chance to warm up each breath before the air is drawn into your lungs).
Understanding how inflammation causes asthma will bring you one step closer to controlling this disease. That's because stopping or preventing inflammation by avoiding the things that trigger it is key to keeping the airways open, which promotes good airflow and comfortable breathing. Understanding the role that inflammation plays also will help you to understand why you may need to take at least two different drugs — one to control or prevent inflammation and another to quickly open constricted airways.
Unraveling asthma's link to inflammation has led to huge advances in treating this disease. This work has laid the groundwork for new classes of drugs aimed at controlling or preventing airway inflammation. These new drugs work hand in hand with the old and still important standbys: drugs that relax and open the airway.
The more you can avoid the things that stir up the inflammatory response, the easier you will breathe.