Asthma is a common, chronic lung disease that inflames and narrows the airways. Asthma causes recurring periods of wheezing, chest tightness, shortness of breath, and coughing. Asthma affects people of all ages, but it most often starts during childhood. In the United States, more than 25 million people are known to have asthma, including about 7 million children. Goals of asthma treatment are reduced impairment from symptoms; minimized risk of asthma attacks and other adverse outcomes, such as hospitalizations and loss of lung function; and minimized side effects of asthma medicines.