There are four core criteria for identifying food poisoning: a large number of patients developing identical symptoms within a short period; all affected individuals sharing the same food intake history; no onset of illness among people who did not consume the suspect food; and disappearance of poisoning symptoms once the implicated food supply is halted.

Symptoms of food poisoning usually emerge 4 to 10 hours after meals, with the peak incidence occurring approximately 6 hours post-ingestion. The earliest manifestation is usually abdominal discomfort, starting with abdominal distension, followed by abdominal pain in many sufferers and acute diarrhea in some individuals. Nausea accompanies abdominal discomfort and will subsequently lead to vomiting.

Food poisoning is categorized into four types: bacterial (e.g., Escherichia coli), chemical (e.g., agricultural pesticides), animal and plant-derived (e.g., pufferfish, hyacinth beans), and fungal (e.g., toxic wild mushrooms). It may occur as isolated cases or mass outbreaks. Typical symptoms include nausea, vomiting, abdominal pain and diarrhea, frequently accompanied by fever. Severe vomiting and diarrhea can trigger dehydration, acidosis, and even shock or coma.