Asthma is a condition where airway hyperresponsiveness due to a chronic inflammatory condition of the lung airways results in episodic airflow obstruction. These episodes of airflow obstruction can present with mild symptoms, such as dry coughing, expiratory wheezing, chest tightness, dyspnea; or severe symptoms, such as respiratory distress, hypoxic seizures, respiratory failure, and even death. There is no definitive cause for asthma, but an interplay of genetic and environmental causes seems likely. Nearly 80% of asthmatics report an onset of asthma before the age of 6 and not all children with recurrent wheeze develop persistent asthma in later childhood. A history of parental asthma, allergies in childhood, severe lower respiratory tract infection, wheezing apart from colds, low birth weight, male gender, and environmental tobacco smoke exposure are considered to be important risk factors for persistent asthma.

The National Asthma Education and Prevention Program classifies asthma based on four parameters: (a) frequency of daytime symptoms, (b) nighttime symptoms, (c) degree of airflow obstruction by spirometry, and/or (d) peak expiratory flow variability. According to this classification, asthmatics can be categorized in four disease severity groups, as “mild intermittent,” “persistent mild,” “persistent moderate,” and “persistent severe.” The goal of asthma management is to reduce airway inflammation by the use of daily “controller” anti-inflammatory medications, minimize exposure to proinflammatory environmental exposures, and controlling comorbid conditions that can worsen asthma.

When exacerbations do occur, early intervention using systemic glucocorticoids and β-agonist bronchodilators can reduce the severity of these episodes. The mild intermittent asthma is the only group where a daily anti-inflammatory (controller) is not used and the β-agonist bronchodilators (reliever) is used for all levels of severity groups. Pharmacotherapy in the management of asthma can be divided into quick-relief medication and long-term control medication. Quick-relief medications are used to manage acute episodes of bronchospasm, which include inhaled β₂-agonists (e.g., albuterol), inhaled anticholinergics (e.g., ipratropium), and short-course
systemic glucocorticoids (e.g., prednisone). Long-term control medications are used to manage mild-to-moderate persistent asthma, which include nonsteroidal anti-inflammatory agents (e.g., cromolyn), inhaled glucocorticoids (e.g., beclomethasone), sustained-release theophylline, long-acting inhaled β-agonists (e.g., salmeterol), and leukotriene modifiers (e.g., montelukast).