Cold medicines send about 7,000 children to hospital emergency rooms each year, according to a new study by the U.S. Centers for Disease Control and Prevention in its first national estimate of the problem. About two-thirds of the cases were children who took the medicines unsupervised. However, about one-quarter involved cases in which parents gave the proper dosage and an allergic reaction or some other problem developed, the CDC reports. The study included both over-the-counter and prescription medicines.