Foodborne illness (also foodborne disease) is any illness resulting from the consumption of food. Foodborne illness is commonly called food poisoning, even though the physiological effects of foodborne illness are not always caused by poisons (toxins). True food poisoning occurs when a person ingests a contaminating chemical or a natural toxin, while most cases of foodborne illness are caused by a variety of foodborne pathogenic bacteria, viruses, prions or parasites that contaminate food.

Such contamination usually arises from improper handling, preparation, or food storage. Good hygiene practices before, during, and after food preparation can reduce the chances of contracting an illness. The action of monitoring food to ensure that it will not cause foodborne illness is known as food safety. Foodborne disease can also be caused by a large variety of toxins that affect the environment.

Foodborne illness can also be caused by the presence of pesticides or medicines in food, or by unintentionally consuming naturally toxic substances like poisonous mushrooms or reef fish.