Heartburn, or gastroesophageal reflux, is surprisingly common in infants. It occurs because the valve that separates the stomach and the esophagus is immature and allows stomach acid to flow into the esophagus. This usually doesn't present many problems beyond spitting up and fussiness (although these babies may need to sleep on their tummies to avoid choking). And most children grow out of it -- typically by toddlerhood.
For some kids, however, reflux continues into the school-age years. These youngsters may suffer from burning pain in the upper abdomen, or even chest, after eating. Other symptoms may include smelly breath, frequent burping, nighttime coughing, or a "bad taste" in the mouth. Although it's unusual (fewer than 5 percent of kids with reflux continue to have it past infancy), reflux in the school-age child nearly always requires treatment with prescription medications -- typically, an antacid like Zantac. When these don't help, and symptoms expand to include difficulty swallowing, for instance, corrective surgery on the esophagus may be warranted.