Asthma is a growing problem, especially in children. It causes frequent wheezing, shortness of breath, chest tightness, and cough. A cold that is caused by a virus (viral cold) can sometimes make asthma symptoms worse. This study will help investigators learn about the way colds are related to asthma attacks among children who need higher amounts of medications to control their asthma. Investigators want to learn why viral colds sometimes cause asthma attacks and other times do not by studying the immune system response in samples taken from the nose and blood.