First of all, if possible, preserve the suspect food, marking it with a warning label to make sure no one else eats it. Second, call or see a medical professional. If the suspect food was served at a large gathering, in a public place such as a restaurant, by a sidewalk vendor or in an employee cafeteria, is a commercial product or was prepared by a grocery store, contact your local health department to report the incident. If vomiting or diarrhoea is experienced (symptoms), drink lots of fluids to prevent dehydration. Physicians and laboratories have a responsibility to contact the health department for some diagnoses of foodborne illness. However, most foodborne illnesses are not diagnosed - symptoms are treated to alleviate discomfort. If food is the suspected source of illness, be sure to seek the advice of a physician.