Since most food poisoning is mild and passes in a few days, most people do not go to a health professional for a diagnosis. You can often diagnose food poisoning yourself if others who ate the same food as you also become ill.

If you do go to your health professional, he or she will make the diagnosis based on your symptoms, a physical exam, and your medical history. Your health professional will ask where you have been eating and whether anyone who ate the same foods has the same symptoms.

Occasionally the following tests are done.

• A stool culture may be done if your health professional suspects that you have eaten contaminated food, your symptoms are severe, or the diagnosis is uncertain.
• Blood tests may be done to help determine whether the food poisoning is caused by bacteria or to rule out other causes. A complete blood count and a chemistry screen can help indicate whether you are severely ill or dehydrated.
• If you are pregnant or have an impaired immune system and have been exposed to toxoplasmosis, you may need a toxoplasmosis test. For more information, see the topic Toxoplasmosis During Pregnancy.

Your health professional may need to report your condition to the health department; this is done to help the government track the condition and identify possible outbreaks.