Diarrhea and Dehydration
Normal newborns' stools shouldn't be hard or formed, but should be more the consistency of mustard and can occur after every feed. Diarrhea, then, is hard to define on an absolute basis, but is considered when stools are more watery or more frequent than usual. One looser than normal stool may not mean much, but several in a row probably do. The cause is often an intestinal viral infection, but more worrisome possibilities include a bacterial infection or food intolerances.
Regardless of the cause of the diarrhea, dehydration can follow very quickly in a small child. The presence of a fever can bring about dehydration even sooner. In general, the younger the child, the faster he or she dehydrates.
Early signs of dehydration are a decrease in the frequency and quantity and a darkening of the urine. Though in an infant with watery stools, this can be hard to gauge. Other signs are a dry-appearing, "sticky" mouth and not producing any tears during crying. Parents are well advised not to wait until any signs that their child appears dry, but to call early if they think there is a risk of dehydration.