Signs and symptoms of gastroenteritis vary among individuals and depend upon the type and quantity of the pathogen (disease-causing organism). Symptoms may appear within hours or days of being infected. They usually last from one to two days but may last 10 days or longer. Diarrhea is the most common symptom. Other symptoms include:

• Loss of appetite
• Nausea
• Vomiting
• Abdominal cramping
• Audible rumbling of intestines
• Malaise (general sick feeling)
• Fever
• Aching muscles
• Exhaustion

Patients who experience severe vomiting and diarrhea due to gastroenteritis may also experience the following signs and symptoms:

• Dehydration, including excessive thirst, weakness, lightheadedness, decreased frequency of urination, dry mouth or lack of tears in infants
  
  
• Low levels of potassium in the blood (hypokalemia)
  
  
• Low levels of sodium in the blood (hyponatremia)
  
  
• Imbalances of water or electrolytes (chemicals needed for normal bodily function)

Most cases of gastroenteritis do not require a visit to a physician. However, 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
• Patient becomes unusually drowsy or confused
• Abdominal pains are severe
• Patients show signs of dehydration