Food poisoning, also called foodborne illness, is illness caused by eating contaminated food. Infectious organisms — including bacteria, viruses and parasites — or their toxins are the most common causes of food poisoning.
Infectious organisms or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked.
Food poisoning symptoms, which can start within hours of eating contaminated food, often include nausea, vomiting or diarrhea. Most often, food poisoning is mild and resolves without treatment. But some people need to go to the hospital.
Food poisoning symptoms vary with the source of contamination. Most types of food poisoning cause one or more of the following signs and symptoms:
Signs and symptoms may start within hours after eating the contaminated food, or they may begin days or even weeks later. Sickness caused by food poisoning generally lasts from a few hours to several days.
If you experience any of the following signs or symptoms, seek medical attention.
Contamination of food can happen at any point of production: growing, harvesting, processing, storing, shipping or preparing. Cross-contamination — the transfer of harmful organisms from one surface to another — is often the cause. This is especially troublesome for raw, ready-to-eat foods, such as salads or other produce. Because these foods aren't cooked, harmful organisms aren't destroyed before eating and can cause food poisoning.
Many bacterial, viral or parasitic agents cause food poisoning. The following table shows some of the possible contaminants, when you might start to feel symptoms and common ways the organism is spread.
|Contaminant||Onset of symptoms||Foods affected and means of transmission|
|Campylobacter||2 to 5 days||Meat and poultry. Contamination occurs during processing if animal feces contact meat surfaces. Other sources include unpasteurized milk and contaminated water.|
|Clostridium botulinum||12 to 72 hours||Home-canned foods with low acidity, improperly canned commercial foods, smoked or salted fish, potatoes baked in aluminum foil, and other foods kept at warm temperatures for too long.|
|Clostridium perfringens||8 to 16 hours||Meats, stews and gravies. Commonly spread when serving dishes don't keep food hot enough or food is chilled too slowly.|
|Escherichia coli (E. coli) O157:H7||1 to 8 days||Beef contaminated with feces during slaughter. Spread mainly by undercooked ground beef. Other sources include unpasteurized milk and apple cider, alfalfa sprouts, and contaminated water.|
|Giardia lamblia||1 to 2 weeks||Raw, ready-to-eat produce and contaminated water. Can be spread by an infected food handler.|
|Hepatitis A||28 days||Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.|
|Listeria||9 to 48 hours||Hot dogs, luncheon meats, unpasteurized milk and cheeses, and unwashed raw produce. Can be spread through contaminated soil and water.|
|Noroviruses (Norwalk-like viruses)||12 to 48 hours||Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.|
|Rotavirus||1 to 3 days||Raw, ready-to-eat produce. Can be spread by an infected food handler.|
|Salmonella||1 to 3 days||Raw or contaminated meat, poultry, milk, or egg yolks. Survives inadequate cooking. Can be spread by knives, cutting surfaces or an infected food handler.|
|Shigella||24 to 48 hours||Seafood and raw, ready-to-eat produce. Can be spread by an infected food handler.|
|Staphylococcus aureus||1 to 6 hours||Meats and prepared salads, cream sauces, and cream-filled pastries. Can be spread by hand contact, coughing and sneezing.|
|Vibrio vulnificus||1 to 7 days||Raw oysters and raw or undercooked mussels, clams, and whole scallops. Can be spread through contaminated seawater.|
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:
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:
To prevent food poisoning at home:
Cook foods to a safe temperature. The best way to tell if foods are cooked to a safe temperature is to use a food thermometer. You can kill harmful organisms in most foods by cooking them to the right temperature.
Cook ground beef to 160 F (71.1 C); steaks, roasts and chops, such as lamb, pork and veal, to at least 145 F (62.8 C). Cook chicken and turkey to 165 F (73.9 C). Make sure fish and shellfish are cooked thoroughly.
Food poisoning is especially serious and potentially life-threatening for young children, pregnant women and their fetuses, older adults, and people with weakened immune systems. These individuals should take extra precautions by avoiding the following foods:
Food poisoning is often diagnosed based on a detailed history, including how long you've been sick, your symptoms and specific foods you've eaten. Your doctor will also perform a physical exam, looking for signs of dehydration.
Depending on your symptoms and health history, your doctor may conduct diagnostic tests, such as a blood test, stool culture or examination for parasites, to identify the cause and confirm the diagnosis.
For a stool culture, your doctor will send a sample of your stool to a laboratory, where a technician will try to identify the infectious organism. If an organism is found, your doctor likely will notify your local health department to determine if the food poisoning is linked to an outbreak.
In some cases, the cause of food poisoning can't be identified.
Treatment for food poisoning typically depends on the source of the illness, if known, and the severity of your symptoms. For most people, the illness resolves without treatment within a few days, though some types of food poisoning may last longer.
Treatment of food poisoning may include:
Antibiotics. Your doctor may prescribe antibiotics if you have certain kinds of bacterial food poisoning and your symptoms are severe. Food poisoning caused by listeria needs to be treated with intravenous antibiotics during hospitalization. The sooner treatment begins, the better. During pregnancy, prompt antibiotic treatment may help keep the infection from affecting the baby.
Antibiotics will not help food poisoning caused by viruses. Antibiotics may actually worsen symptoms in certain kinds of viral or bacterial food poisoning. Talk to your doctor about your options.
Adults with diarrhea that isn't bloody and who have no fever may get relief from taking the medication loperamide (Imodium A-D) or bismuth subsalicylate (Pepto-Bismol). Ask your doctor about these options.
Food poisoning often improves without treatment within 48 hours. To help keep yourself more comfortable and prevent dehydration while you recover, try the following:
If you or your child needs to see a doctor, you'll likely see your primary care provider first. If there are questions about the diagnosis, your doctor may refer you to an infectious disease specialist.
Preparing a list of questions will help you make the most of your time with your doctor. Some questions to ask include:
Some questions the doctor may ask include:
Drink plenty of fluids. Stick with bland foods to reduce stress on your digestive system. If your child is sick, follow the same approach — offer plenty of fluids and bland food. If you're breast-feeding or using formula, continue to feed your child as usual.
Ask your child's doctor if giving your child an oral rehydration fluid (Pedialyte, Enfalyte, others) is appropriate. Older adults and people with weakened immune systems might also benefit from oral rehydration solutions. Medications that help ease diarrhea generally aren't recommended for children.