Asthma causes inflammation of the lungs and results in narrowing of the respiratory passages. Inflammation is a normal reaction of the body to any injury or infection. In order to heal the injury or fight the infection, two reactions take place. First, the blood supply to the affected part of the body increases and second, the disease-fighting cells from the surrounding tissues rush in. These reactions cause redness and swelling at the site of injury. The body also produces antibodies to fight the infection. Antibodies are a special type of blood protein that is produced in response to any disease causing agent. After the injury is healed or the infection cured, the inflammation also subsides.The inflammation of the lungs and respiratory passages caused due to asthma does not subside after the reaction to an irritant is controlled. Almost everyone with chronic asthma has symptoms of inflammation in the respiratory passages all the time. Prolonged, continuous and uncontrolled inflammation can destroy the tissues of the respiratory passages. When the tissues of the respiratory passages are destroyed, the functions of the lungs are adversely affected. Chronic inflammation also leads to the formation of scars in the walls of the airways. If scars are formed and the walls of the bronchi get permanently damaged, asthma does not respond to common treatment any more. This is why it is important to take medicines that reduce inflammation of the airways.