Symptoms of stomach flu include abdominal cramping, stomach pain, vomiting, nausea and diarrhea, according to WebMD. Stomach flu is also referred to as gastroenteritis, and it may be caused by bacteria, a virus or parasites found in unclean water or expired food.
With more severe instances of stomach flu, bodily fluid loss can leave an afflicted person with dehydration, which constitutes a medical emergency and requires immediate evaluation by physician, according to WebMD. Symptoms of dehydration include sunken eyes, increased thirst, a feeling of lightheadedness, decreased urinary output and dry mouth. Other symptoms include lack of skin elasticity and decreased tears. Dehydration can be avoided by taking in sufficient fluids when suffering from stomach flu.
While most symptoms of stomach flu can be easily treated at home, some symptoms require attention from a medical professional, according to WebMD. In addition to dehydration, fever in excess of 101 degrees Fahrenheit, blood in the stool or vomit, or vomiting that persists for more than 48 hours are all causes for alarm. Abdominal pain accompanied by swelling on the lower right-hand side of the abdomen can be indicative of a serious condition and should also be evaluated as soon as possible to rule out a more innocuous condition.