Pharmacologic therapy is used to prevent and control asthma symptoms, reduce the frequency and severity of asthma exacerbations, and reverse airflow obstruction. Asthma medications are categorized into two general classifications: quick-relief and long-term medications. Quick-relief medications are taken to provide prompt reversal of acute airflow obstruction and relief of accompanying bronchoconstriction. Long-term control medications are taken daily on a long term basis to help achieve and maintain control of persistent asthma. Patients who have persistent asthma require medication from both classifications.