Common symptoms of foodborne illness include diarrhea, abdominal cramping, fever, headache, vomiting, severe exhaustion, and sometimes blood or pus in the stools. However, symptoms will vary according to the type of bacteria and by the amount of contaminants eaten.
In rare instances, symptoms may come on as early as a half hour after eating the contaminated food but they typically do not develop for several days or weeks. Symptoms of viral or parasitic illnesses may not appear for several weeks after exposure. Symptoms usually last only a day or two, but in some cases can persist a week to 10 days. For most healthy people, foodborne illnesses are neither long-lasting nor life-threatening. However, they can be severe in the very young, the very old, and people with certain diseases and conditions.
These conditions include:
Source: Excerpted from FDA Consumer - The Unwelcome Dinner Guest: Preventing Foodborne Illness, Jan.-Feb. 1991; Revised Dec. 1997, Feb. 1999, Oct. 1999, June 2000, July 2002 and March 2003