In a concession to pediatricians, drug companies warned parents not to give over-the-counter cold remedies to children under 4.
Doctors doubt the drugs do children much good and worry about risks.
The companies that make medications like Dimetapp and PediaCare also warned parents not to give antihistamines to kids to help them sleep. The new instructions are on packages that began hitting stores this week.
Problems with over-the-counter cough and cold medicine send about 7,000 children to emergency rooms each year, with symptoms including hives, drowsiness and unsteady walking.
The changes came after discussions between drug companies and the Food and Drug Administration. A petition signed by pediatricians had sought to ban the medications for children under 6.