The conditions affecting the air passageways and air sacs throughout the lungs proper are infections and obstructive airways diseases. Obstructive airways diseases are characterised by restricted expiratory airflow. Bronchial asthma is a reversible condition caused by bronchospasm, mucus hypersecretion and oedema. Chronic obstructive airways disorders (COADs), also referred to as chronic obstructive pulmonary disease (COPD), are a group of respiratory diseases characterised by chronic and recurrent obstruction of the airways. The term is usually associated with chronic bronchitis and emphysema. Cystic fibrosis, an inheritable disorder affecting exocrine gland function, leads to abnormal secretions that obstruct the airways and pancreatic ducts. It shares many of the characteristics of the COADs. In this section, the discussion focuses on bronchial asthma, although many of the drugs used in this therapy are applicable to the management of the COADs.