Food poisoning is caused by bacteria, viruses or toxins in the food we eat. Some of these toxins are found naturally in foods, while some have accumulated in the environment. Show If you have food poisoning you’ll probably have gastroenteritis symptoms such as abdominal cramps, diarrhoea or vomiting, or flu-like symptoms. Food poisoning can also cause serious long-term problems like kidney failure. Occasionally people die from food poisoning. Some wild mushrooms, including the death cap, are extremely poisonous. You should not eat wild-harvested mushrooms unless they have been definitely identified as safe. Seek immediate medical treatment If you think you may have eaten poisonous mushrooms. Large fish, such as shark, swordfish and marlin, may accumulate relatively high levels of mercury. You should limit your consumption of these fish, especially if you are a child, are pregnant or planning pregnancy. What are the symptoms and causes of food poisoning?You may be sick with food poisoning but not know what food caused it or even that you have it. Different bacteria and viruses can have different effects:
Food needs to be stored, handled and cooked carefully and at temperatures that avoid the spread and growth of bacteria that can make you sick. Read about preparing food safely. What are the high-risk groups for food poisoning?If you’re pregnant, elderly or very young, or your immune system is weak through illness or drugs, you’re at greater risk of food poisoning and possibly serious complications. If you’re pregnant, listeria can cause you to miscarry, even if you don’t know you’ve been infected. If you notice symptoms — usually like a mild flu but also diarrhoea, vomiting and nausea — contact your doctor immediately. Read more about how to avoid listeria on the Pregnancy, Birth and Baby website. How is food poisoning treated?Most people don’t need medical help for food poisoning, as their symptoms are not severe and don’t last long. However, people in high-risk groups (such as babies and elderly people) should see a doctor early on, to make sure they don’t get dehydrated. For children, see your GP or call healthdirect on 1800 022 222 (known as NURSE-ON-CALL in Victoria) if your child has diarrhoea that lasts for more than a few days or has bloody diarrhoea. Take your child to the emergency department immediately if:
For adults, seek medical advice if:
For a mild case of food poisoning, you may try sucking ice chips, replacing lost fluids and electrolytes (you can buy an oral rehydration solution from your pharmacy) and easing back into your normal diet and routine when you feel ready. Antibiotics may help with some bacterial types of food poisoning, but are usually not needed.
Food can become contaminated at any stage during its production, processing or cooking. For example, it can become contaminated by:
Cross-contamination can occur, for example, if you prepare raw chicken on a chopping board and don't wash the board before preparing food that won't be cooked (such as salad), as the harmful bacteria can be spread from the chopping board to the salad. It can also occur if raw meat is stored above ready-to-eat meals and juices from the meat drip on to the food below. See preventing food poisoning for information about reducing these risks Types of infectionFood contamination is usually caused by bacteria, but it can also sometimes be caused by viruses or parasites. Some of the main sources of contamination are described below. CampylobacterIn the UK, campylobacter bacteria are the most common cause of food poisoning. The bacteria are usually found on raw or undercooked meat (particularly poultry), unpasteurised milk and untreated water. The incubation period (the time between eating contaminated food and the start of symptoms) for food poisoning caused by campylobacter is usually between two and five days. The symptoms usually last less than a week. SalmonellaSalmonella bacteria are often found in raw or undercooked meat, raw eggs, milk, and other dairy products. The incubation period is usually between 12 and 72 hours. The symptoms usually last around four to seven days. ListeriaListeria bacteria may be found in a range of chilled, "ready-to-eat" foods, including pre-packed sandwiches, cooked sliced meats and pâté, and soft cheeses (such as Brie or Camembert). All of these foods should be eaten by their "use-by" dates. This is particularly important for pregnant women, because a listeria infection (known as listeriosis) in pregnancy can cause pregnancy and birth complications, and can result in miscarriage. The incubation period can vary considerably, from a few days to several weeks. The symptoms will usually pass within three days. Escherichia coli (E. coli)Escherichia coli, often known as E. coli, are bacteria found in the digestive systems of many animals, including humans. Most strains are harmless but some can cause serious illness. Most cases of E. coli food poisoning occur after eating undercooked beef (particularly mince, burgers and meatballs) or drinking unpasteurised milk. The incubation period for food poisoning caused by E. coli is typically one to eight days. The symptoms usually last for a few days or weeks. ShigellaShigella bacteria can contaminate any food that has been washed in contaminated water. Symptoms typically develop within seven days of eating contaminated food and last for up to a week. An infection caused by Shigella bacteria is known as bacillary dysentery or shigellosis. See the topic on dysentery for more information about it. VirusesThe virus that most commonly causes diarrhoea and vomiting is the norovirus. It's easily spread from person to person, through contaminated food or water. Raw shellfish, particularly oysters, can also be a source of infection. The incubation period typically lasts 24-48 hours and the symptoms usually pass in a couple of days. In young children, the rotavirus is a common cause of infection from contaminated food. The symptoms usually develop within a week and pass in around five to seven days. ParasitesIn the UK, food poisoning caused by parasites is rare. It's much more common in the developing world. Parasitic infections that can be spread in contaminated food include:
The symptoms of food poisoning caused by a parasite usually develop within 10 days of eating contaminated food, although sometimes it may be weeks before you feel unwell. If left untreated, the symptoms can last a long time – sometimes several weeks or even a few months. Medically Reviewed by Neha Pathak, MD on September 17, 2021 If you’ve ever had food poisoning, you probably had a good idea that’s what it was even before you talked to your doctor. It’s hard to miss the main symptoms: stomach cramps, vomiting, and diarrhea. They can hit a few hours or a day or two after you eat the food that caused the problem. Your symptoms usually pass in a few days or even in mere hours. But if your discomfort doesn’t go away, you may need to get checked and find out exactly what made you sick. You should also see a doctor if along with other symptoms you have high fever, blood in your stool, or feel dehydrated or unable to keep any food or liquid down. Your doctor may be able to tell you what caused it after running tests. But they aren’t always necessary and don’t confirm every case. Many times, your doctor will diagnose food poisoning based simply on your symptoms. While the main symptoms are nausea, diarrhea, vomiting, and stomach cramps, you also may have a fever, headache, muscle and joint aches, or blood in your stool. You may also be dehydrated, so your mouth and throat feel dry and you don’t pee as often as you typically do. Dehydration can make you dizzy when you stand up. Rarely, food poisoning can cause blurry or double vision, tingling, or weakness. More than 250 bacteria, viruses, and parasites are known to cause food poisoning. They can exist in foods at any stage, such as when they're growing, packaged, shipped, stored, or cooked. Certain foods are more likely to harbor bad germs. These include raw eggs, unpasteurized milk and juice, soft cheeses, and raw or undercooked meat or seafood. Fresh produce is another risk. Foods made in bulk are problematic, too. A single bad egg could affect the whole batch of omelets in a buffet. You could make trouble for yourself by not washing the cutting board or your hands as you prepare different foods. Your chances of getting food poisoning are higher in the summer. In 90-degree heat, food can start to spoil within an hour. At a picnic or during a camping trip, you are more likely to eat undercooked grilled meats or to handle raw meat without access to soap and water. Bacteria can grow quickly inside tepid coolers. So if you're picnicking on a hot day, put leftovers back in with fresh ice. In 4 out of 5 cases of food poisoning, you never find out exactly what caused it. That's OK because you most likely will get better on your own. But in cases where the culprit is found, it's usually one of the following: Some bacteria cause fewer cases of food poisoning but can make you very sick. They can even cause death. They include: If your illness is severe or complicated, your doctor may run some of the following tests. Stool cultures are the most common lab test for food poisoning. Your doctor may order one if you have a fever, ntense stomach pain, or bloody diarrhea, or if there is an outbreak that is being tracked. They may also order one if you have symptoms that linger. A sample of your stool can help tell if your sickness is related to bacteria. It can even reveal the germ’s DNA “fingerprint” and which antibiotics will kill it. Viruses are more difficult to see in culture, so if the specific virus needs to be identified, your doctor may order stool tests to look for the germ's DNA fingerprint.Microscopic exams of stool can identify parasites. Stool tests aren’t always accurate, and they can take several days to come back. Blood tests may be ordered if your doctor thinks the infection has spread into the blood. Blood tests can detect the bacteria Listeria monocytogenes and the hepatitis A virus. Specific blood tests can tell how sick you are by looking for inflammation and signs that you’re dehydrated. Stool or blood tests can check for toxins, such as for botulism, which can be deadly. Imaging tests such as MRIs and CT scans aren’t often used in food poisoning cases. But they can help rule out other causes for your symptoms. A host of other conditions can lead to many of the same symptoms of food poisoning. Most common is mon-foodborne gastroenteritis, which is most often caused by a virus. For instance, Norovirus causes both foodborne gastroenteritis (from contaminated food or water) and viral gastroenteritis from person to person spread. Other causes include gallbladder problems, pancreatitis, and inflammatory bowel disease. So figuring out if you have food poisoning is as much about the timing as it is about the symptoms themselves. In most cases, food poisoning usually shows up hours or days after you’ve eaten something that made you sick. That can make it hard to know if it's food poisoning or something else. The delay also makes it tricky to trace the illness back to the specific food or drink. But different organisms work at different speeds. For example, Staphylococcus aureus can give you cramps, diarrhea, and nausea in as little as 30 minutes after you eat or drink. This bacterium grows in meats, eggs, and cream that haven’t been refrigerated properly. Another, far less common, cause of foodborne illness is the hepatitis A virus. It can lie in wait as long as 50 days before making itself known. You can get the virus through foods and drinks that have been in contact with sewage water. You’re more likely to get the virus when traveling in developing countries. Call 911 if you think the food poisoning may be from seafood or wild mushrooms, or if the person is severely dehydrated. First, control nausea and vomiting:
It’s important to prevent dehydration:
Call a doctor right away if symptoms last more than 3 days or you have: Food safety for high-risk groups Food poisoning is more common and riskier for people with weakened immune systems, infants and young children, pregnant women, and the elderly. If you fall into one of these groups, try to avoid:
Food safety in the grocery store Before you load items into the shopping cart: Food safety in the kitchen These tips will help make your home-cooked meals safe: Food safety while eating out You have more control over the safety of foods cooked at home than in a restaurant. But you can still take some safe steps when eating out: Food safety while traveling Who doesn’t love a vacation? But you need to be careful when you travel, especially to developing countries. Other safety tips |