The symptoms from the most common types of food poisoning generally start within 2 - 6 hours of eating the food. That time may be longer (even a number of days) or shorter, depending on the cause of the food poisoning.

Possible symptoms include:

• Abdominal cramps
• Diarrhea (may be bloody)
• Fever and chills
• Headache
• Nausea and vomiting
• Weakness (may be serious and lead to respiratory arrest, as in the case of botulism)

Your health care provider will examine you for signs of food poisoning, such as tenderness in the abdomen and dehydration. Your provider will also ask about foods you have eaten recently.

Tests to find the cause may be done on your:

• Blood
• Leftover food
• Stool
• Vomit

Even if you have food poisoning, however, these tests may not be able to prove it.

In rare but possibly serious cases, your health care provider may order one or more of the following procedures:

• A thin, tube-like tool placed in the anus to look for the source of bleeding or infection (sigmoidoscopy)
• A test to measure electric impulses in the muscles (electromyography) to check for botulism
• A test of fluid from the spine (lumbar puncture) if you have signs of a nervous system disorder