Food Poisoning

What is food poisoning?

Food poisoning is an illness that you may get after eating food or drinking water contaminated by some types of bacteria, parasites, and viruses.

What is the cause?


Bacteria are all around you—on your hands, countertops, floor, everywhere. Eating a few bacteria usually will not hurt you. However, some types of bacteria in food can make you sick.

You may get infected if:

  • You eat or drink dairy products that have not been pasteurized (heated to kill certain bacteria) by the manufacturer.
  • You eat contaminated food, especially raw or undercooked meat.
  • You eat food that has not been canned or preserved properly.
  • You eat food that has been handled by someone who is infected.
  • You swallow water from a well, lake, stream, or city water that has not been treated to kill germs.
  • You have contact with an infected animal.


The viruses that cause food poisoning may be in water that has been contaminated with human bowel movements. The viruses get into seafood, such as oysters, clams, and other shellfish. If you drink the water or eat the seafood raw or partially cooked, you may become ill.


Parasites such as roundworms in pork and wild game (for example, bear), can also cause food poisoning.

What are the symptoms?

Symptoms depend on the cause, and may include:

  • Nausea
  • Vomiting
  • Frequent loose, watery, unformed bowel movements, which may be bloody
  • Belly pain
  • Fever

In rare cases, some kinds of food poisoning may cause weakness, blurred vision, or trouble speaking, swallowing, or breathing.

Depending on the cause, you may start having symptoms minutes to months after you eat contaminated food. The most common types of food poisoning cause symptoms in 30 minutes to 2 days.

How is it diagnosed?

Food poisoning is often suspected if several people get sick after eating the same food. Your healthcare provider will ask about your symptoms and food you have eaten. Your provider may ask for samples of the food. You may have tests of bowel movements to look for bacteria, viruses, or parasites.

How is it treated?

Treatment depends on how sick you are and what is causing the illness. It usually takes about 1 to 5 days to recover fully from food poisoning.

Infants, young children, pregnant women, adults over age 65, and people with a chronic disease or weak immune system can become seriously ill from food poisoning. In such cases, it is especially important to contact a healthcare provider when food poisoning is suspected.

How can I take care of myself?

Follow the full course of treatment prescribed by your healthcare provider. In addition:

  • Drink enough liquids to keep your urine light yellow in color.
  • Rest your stomach and bowel but make sure that you keep getting liquids. You can do this by not eating anything and by drinking clear liquids only. Clear liquids include water, weak tea, fruit juice mixed half and half with water, Jell-O, or clear soft drinks without caffeine (like lemon-lime soda). Stir soda until the bubbles are gone (the bubbles can make vomiting worse).
  • Avoid liquids that are acidic, like orange juice, or caffeinated, like coffee.
  • If you have severe diarrhea, your body can lose too much fluid and you can get dehydrated. Dehydration can be very dangerous, especially for children and older adults. You may also be losing minerals that your body needs to keep working normally. Your healthcare provider may recommend an oral rehydration solution (ORS), which is a drink that replaces liquids and minerals.
  • You may eat soft, plain foods. Good choices are soda crackers, toast, plain noodles, or rice, cooked cereal, applesauce, and bananas. Eat small amounts slowly and avoid foods that are hard to digest or may irritate your stomach, such as foods with acid (like tomatoes or oranges), spicy or fatty food, meats, and raw vegetables. You may be able to go back to your normal diet in a few days.
  • If you have cramps or belly pain, it may help to put a hot water bottle or heating pad on your belly. Cover the hot water bottle with a towel or set the heating pad on low so you don’t burn your skin.
  • Don’t take aspirin, ibuprofen, or other nonsteroidal anti-inflammatory drugs (NSAIDS) without checking first with your healthcare provider. NSAIDs, such as ibuprofen, naproxen, and aspirin, may cause stomach bleeding and other problems. These risks increase with age. Read the label and take as directed. Unless recommended by your healthcare provider, you should not take this medicine for more than 10 days.
  • You can buy nonprescription medicine to treat diarrhea at the drugstore. If you use it, make sure you use only the dose recommended on the package. Don’t use the medicine for more than 2 days without checking with your healthcare provider. If you have chronic health problems, always check with your provider before you use any medicine for diarrhea.

How can I help prevent food poisoning?

Follow these guidelines to prevent food poisoning:

  • Wash your hands and clean any dishes or utensils before you prepare, cook, serve, or eat food. Keep kitchen counters and other food preparation surfaces clean. Replace used dishcloths and kitchen towels with clean ones often.
  • Cover any sore or cut on your hands before preparing food. Use rubber gloves or cover the sore with a clean bandage.
  • Make sure the milk, cheese, and juice products you eat and drink have been pasteurized by the manufacturer (heated to kill certain bacteria).
  • Wash fruits and vegetables well, especially if you are eating them raw.
  • Thaw frozen meats in the refrigerator or a microwave. Do not let meat stand at room temperature.
  • Keep juices from raw meat, poultry, and seafood away from other foods.
  • Cook all meat thoroughly. Use a meat thermometer to make sure meat is cooked enough to kill bacteria. Pork should be heated to an internal temperature of at least 160°F (71°C). Ground beef should be cooked until a thermometer inserted into several parts of the patty reads at least 160°F (71°C). Ground beef can turn brown during cooking before bacteria in the meat are killed. For whole chickens and turkeys a temperature of 180°F (82°C) is recommended for thigh meat and 170°F (77°C) for breast meat.
  • Refrigerate any food you will not be eating right away.
  • If you are served undercooked meat at a restaurant, send it back for further cooking. Ask for a clean plate, and for sandwiches, ask for a new bun.
  • If you are camping or won’t be where you can get filtered water, bring a way to purify water, such as a filter or purifier, chlorine or iodine tablets, or a pot and stove for boiling water. If you need to buy a water filter or purifier, buy one that can filter out organisms as small as the ones that cause giardiasis, cholera, and amoebic diarrhea.
  • Wash your hands after you go to the bathroom. Teach children to wash their hands carefully with soap and water after using the toilet and before having a snack or meal.
  • If you take care of young children, wash your hands often and dispose of diapers carefully so that bacteria can’t spread to other surfaces or people.
  • Keep children with diarrhea home from daycare and school until they have stopped having diarrhea.
  • Throw out dented cans and damaged food containers.
  • Boil home-canned food for 10 minutes or heat it at 176°F (80°C) for 30 minutes.

You can get more information on food poisoning and safe food handling from:

Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth.
Last modified: 2015-01-06
Last reviewed: 2014-10-20
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.

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