what are the causes signs and symptoms of asthma?
['Shortness of breath.', 'Chest tightness or pain.', 'Wheezing when exhaling, which is a common sign of asthma in children.', 'Trouble sleeping caused by shortness of breath, coughing or wheezing.', 'Coughing or wheezing attacks that are worsened by a respiratory virus, such as a cold or the flu.']