Asthma is a chronic inflammatory disease of the airways in which the smaller passages of the lungs narrow. This causes wheezing, shortness of breath, mucus production and coughing. Symptoms can be controlled using anti-inflammatory drugs, bronchodilators, or leukotriene modifiers. Some of these drugs are preventative medications that must be taken on a regular basis (but cannot be used to treat acute attacks), while other are relief medications.