Gastroenteritis is a general term to describe a variety of infectious conditions that result in irritation or inflammation of the stomach and small and large intestines.

The primary symptom of gastroenteritis is diarrhea, which occurs when the intestines secrete and/or are unable to reabsorb fluid. This can result from damage to the cells lining the intestines, which can have numerous infectious and noninfectious causes.

As a result, stools contain more water, causing them to become watery and runny. Other symptoms and complications of gastroenteritis (e.g., dehydration) are often related to diarrhea.

In healthy adults, gastroenteritis is not usually a serious condition, and recovery typically occurs after several days with no lasting problems. However, in very young people, unhealthy adults and those with weakened immune systems, gastroenteritis can cause dehydration and imbalance of electrolytes (chemicals necessary for normal bodily function).

A physician should be consulted if:

• Symptoms persist for longer than 36 hours
• Blood is present in diarrhea or vomit
• Patients have a fever of 103 degrees Fahrenheit (39.4 degrees Celsius) or higher
• Patients feel lightheaded or faint after standing
• Patients become unusually drowsy or confused
• Abdominal pains are severe
• Patients show signs of dehydration

Eosinophilic gastroenteritis is a rare disease in which the lining of the stomach and the large and small intestines become infiltrated with a type of white blood cell called eosinophils. Unlike other types of gastroenteritis, it can involve any part of the gastrointestinal tract from the esophagus to the rectum.