A person with food poisoning has inflammation of the stomach and intestines, caused by the ingestion of a bacterial toxin that is present in contaminated food or water. In some cases, food poisoning may also be caused by the direct ingestion of harmful bacteria present in contaminated food or water.

The symptoms of food poisoning usually develop within 6 hours of eating (or drinking) the contaminated food. In some cases, the symptoms may take as long as 48 hours to develop.

Traveler's diarrhea is one form of food poisoning that occurs after consuming bacteria present in contaminated food or water in an underdeveloped country.