If you experience any of the following signs or symptoms, seek medical attention.
Frequent episodes of vomiting and inability to keep liquids down
Bloody vomit or stools
Diarrhea for more than three days
Extreme pain or severe abdominal cramping
An oral temperature higher than 100.4 F (38 C)
Signs or symptoms of dehydration — excessive thirst, dry mouth, little or no urination, severe weakness, dizziness, or lightheadedness
Neurological symptoms such as blurry vision, muscle weakness and tingling in the arms.
Whether you become ill after eating contaminated food depends on the organism, the amount of exposure, your age and your health. High-risk groups include:
Older adults. As you get older, your immune system may not respond as quickly and as effectively to infectious organisms as when you were younger.
Pregnant women. During pregnancy, changes in metabolism and circulation may increase the risk of food poisoning. Your reaction may be more severe during pregnancy. Rarely, your baby may get sick, too.
Infants and young children. Their immune systems haven’t fully developed.
People with chronic disease. Having a chronic condition — such as diabetes, liver disease or AIDS — or receiving chemotherapy or radiation therapy for cancer reduces your immune response.
The most common serious complication of food poisoning is dehydration — a severe loss of water and essential salts and minerals. If you’re a healthy adult and drink enough to replace fluids you lose from vomiting and diarrhea, dehydration shouldn’t be a problem.
Infants, older adults and people with suppressed immune systems or chronic illnesses may become severely dehydrated when they lose more fluids than they can replace. In that case, they may need to be hospitalized and receive intravenous fluids. In extreme cases, dehydration can be fatal.
Some types of food poisoning have potentially serious complications for certain people. These include:
Listeria infection. Complications of a listeria food poisoning may be most severe for an unborn baby. Early in pregnancy, a listeria infection may lead to miscarriage. Later in pregnancy, a listeria infection may lead to stillbirth, premature birth or a potentially fatal infection in the baby after birth — even if the mother was only mildly ill. Infants who survive a listeria infection may experience long-term neurological damage and delayed development.
Escherichia coli (E. coli). Certain E. coli strains can cause a serious complication called hemolytic uremic syndrome. This syndrome damages the lining of the tiny blood vessels in the kidneys, sometimes leading to kidney failure. Older adults, children younger than 5 and people with weakened immune systems have a higher risk of developing this complication. If you’re in one of these risk categories, see your doctor at the first sign of profuse or bloody diarrhea.