The signs and symptoms of foodborne illness vary according to the type and amount of contaminant ingested. In most cases, the signs and symptoms resemble those of the stomach flu. They may range from mild to severe in intensity and may last a few hours to several days. They include:

• Abdominal cramps
• Nausea
• Vomiting
• Diarrhea (sometimes bloody)
• Fever
• Dehydration

In most cases, foodborne illnesses are not serious and the bacteria usually pass through the system in 24 to 48 hours. However, a physician should be consulted if:

• The patient is elderly, younger than age 3 or has a disease that weakens the immune system, such as cancer.
  
  
• Nausea, vomiting or diarrhea last longer than two days.
  
  
• Symptoms begin after foreign travel.
  
  
• Other friends or family members also experience symptoms after eating the same food.
  
  
• Liquids or medications cannot be kept in the stomach due to vomiting.
  
  
• The patient’s condition does not improve within two days despite drinking large amounts of fluid.
  
  
• Nervous system symptoms are present, such as slurred speech, muscle weakness, double vision or difficulty swallowing.

The following signs and symptoms may require immediate medical attention:

• Signs of shock, such as weak or rapid pulse, shallow breathing and shaking or chills.
  
  
• Signs of severe dehydration, such as dry mouth, decreased urine output and sunken eyes.
  
  
• Confusion or difficulty reasoning.