Symptoms

The symptoms of food poisoning usually affect your stomach and intestines (gastrointestinal tract).

• The first symptom is usually diarrhea.
• Other symptoms include feeling sick to your stomach (nausea), vomiting, and abdominal (belly) cramps.

The time it takes for symptoms to appear, how severe the symptoms are, and how long the symptoms last depend on the infecting organism, your age, and your overall health.

The very young and the very old may be most affected by food poisoning. Their symptoms may last longer, and even the types of food poisoning that are typically mild can be life-threatening. This may also be true for pregnant women and people with impaired immune systems, such as those who have long-lasting (chronic) illnesses.

Not all food poisoning causes diarrhea, nausea, vomiting, and belly cramps. Some types of food poisoning have different or more severe symptoms. These can include weakness, numbness, confusion, or tingling of the face, hands, and feet.

See Cause for more information about specific symptoms for each organism.

Gastrointestinal symptoms, such as diarrhea and vomiting, can also be caused by organisms that aren't necessarily spread through food. These organisms are mainly spread through water or personal contact. Conditions caused by these organisms include infection with the parasite Giardia lamblia.

What Happens

You may become ill with food poisoning after you eat food that contains bacteria, viruses, or other harmful organisms. Most cases of food poisoning follow the same general course.

After you eat a contaminated food, there is an hours-to-days delay before you notice symptoms. The contaminating organism passes through the stomach into the intestine, attaches to the intestinal walls, and begins to multiply. Some organisms stay in the intestine. Some produce a toxin that is absorbed into the bloodstream. And others directly invade body tissues. Your symptoms depend greatly on the type of organism that has infected you.

Different organisms cause similar symptoms, especially diarrhea, vomiting, and stomach cramps. Diarrhea and vomiting are a normal response as the body tries to rid itself of harmful organisms. Unless the illness is part of a recognized outbreak, it's difficult to identify the infecting organism. Lab tests usually aren't done.

In most cases, you recover in a few days to a week as toxins are flushed from your system. You may feel weak for several days after other symptoms go away.

Most of the time, food poisoning is mild and passes in a few days. But the symptoms and course of some types of food poisoning may be more severe. To learn more, see Cause for a list of specific organisms.

In rare cases, food poisoning can result in kidney or joint damage.²