The poisoning occurs after ingesting poisonous species of mushrooms or plants or contaminated fish or shellfish.
The most common symptoms are diarrhea, nausea, and vomiting and sometimes seizures and paralysis.
The diagnosis is based on symptoms and examination of the ingested substance.
Avoiding wild or unfamiliar mushrooms and plants and contaminated fish reduces the risk of poisoning.
Replacing fluids and ridding the stomach of the toxic substance are the best forms of treatment, but some substances are deadly.
(See also Overview of Poisoning Overview of Poisoning Poisoning is the harmful effect that occurs when a toxic substance is swallowed, is inhaled, or comes in contact with the skin, eyes, or mucous membranes, such as those of the mouth or nose... read more .)
Many disorders cause sudden vomiting and diarrhea due to inflammation of the digestive tract (gastroenteritis Gastroenteritis ). Sometimes people loosely refer to all of these disorders as "food poisoning." However, only gastroenteritis caused by a toxin that was eaten is true food poisoning. Most vomiting and diarrhea is caused by a digestive tract infection from a virus or bacteria, which is not considered food poisoning unless the bacteria in contaminated food produce such toxins (see Staphylococcal Food Poisoning Staphylococcal Food Poisoning Staphylococcal food poisoning results from eating food contaminated with toxins produced by certain types of staphylococci, resulting in diarrhea and vomiting. This disorder can be caused by... read more 
). Also, many poisonous plants Plant and Shrub Poisoning Only a few commonly grown plants are very poisonous, but many others have less serious toxic effects. Generally, poisoning is unlikely unless a plant is highly toxic or large quantities are... read more , mushrooms Mushroom (Toadstool) Poisoning Many species of mushroom are poisonous and can cause different symptoms depending on the type of mushroom. Different species of mushrooms produce different toxins with different effects Even... read more , and seafood Fish and Shellfish Poisoning Certain types of fresh or frozen fish or shellfish may contain toxins that can cause a variety of symptoms. Vomiting and diarrhea ( gastroenteritis) caused by toxins is different from gastroenteritis... read more contain toxins that affect the digestive tract and sometimes other organs.
Gastroenteritis may also affect people who have ingested foods contaminated by external toxins, such as
Unwashed fruits and vegetables sprayed with arsenic, lead Lead Poisoning Lead poisoning affects many parts of the body, including the brain, nerves, kidneys, liver, and blood. Children are particularly susceptible because their nervous system is still developing... read more , or organic insecticides Insecticide Poisoning Insecticides are chemicals used to kill insects. Some insecticides are also dangerous to humans. Many insecticides can cause poisoning after being swallowed, inhaled, or absorbed through the... read more
Acidic fluids served in lead-glazed pottery
Food stored in cadmium-lined containers
Treatment of Food Poisoning
Most people with food poisoning recover fully and rapidly with nothing more than replacement of fluids and electrolytes Overview of Electrolytes Well over half of the body's weight is made up of water. Doctors think about the body's water as being restricted to various spaces, called fluid compartments. The three main compartments are... read more . As soon as symptoms begin, a person should try to consume large amounts of fluids. If fluids cannot be tolerated, the person needs to go to an emergency department for intravenous fluids.
If possible, it is often a good idea to rid the stomach of the toxic substance as quickly as possible. For most people, vomiting accomplishes this task.
Specific treatments are sometimes given when the toxin is known.
