The main complication of viral gastroenteritis is dehydration — a severe loss of water and essential salts and minerals. If you're healthy and drink enough to replace fluids you lose from vomiting and diarrhea, dehydration shouldn't be a problem. Infants, older adults and people with weakened immune systems may become severely dehydrated when they lose more fluids than they can replace. Hospitalization might be needed so that lost fluids can be replaced through an IV in their arms. Dehydration can rarely lead to death.