In the case of food poisoning caused by bacteria, viruses or parasites, a diagnosis can usually be made based on symptoms and a physical examination. Your doctor may order tests targeting blood components whose loss would lead to dehydration, or it could ask for a stool sample to enable it to detect the presence of bacteria or parasites.
When it comes to other types of food poisoning, early establishment of the correct diagnosis is of vital importance. Some poisons have specific antitoxins which neutralize their effects completely.
When food poisoning affects groups of people, it is easier to identify the cause. Often all those affected have eaten a food joint, and analysis can be conducted to determine toxicity.