Food poisoning

and Carola Felchner, science journalist

Sophie Matzik is a freelance writer for the medical team.

More about the experts

Carola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.

More about the experts All content is checked by medical journalists.

Food poisoning results from the consumption of food that has been spoiled by poisons or pathogens (such as bacteria). Typical symptoms are stomach pain, diarrhea, and vomiting. Mild food poisoning usually heals on its own within a few days. In more severe cases, however, patients must be treated in hospital. Read here about the symptoms of food poisoning, how it is treated and how it can be prevented!

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. A05

Brief overview

• What is Food Poisoning? Strictly speaking, it means poisoning from the consumption of food that has been spoiled by toxins. In a broader sense, food infection (consumption of food that has been spoiled by pathogens) is also referred to as food poisoning.
• Causes: Toxins (food poisoning in the strict sense); Bacteria (as in salmonella poisoning, listeriosis, botulism), fungi, viruses or parasites (food poisoning in the broader sense or food infection)
• Symptoms: mostly nausea, vomiting, diarrhea, abdominal cramps; often other complaints depending on the trigger
• Treatment: depending on the cause and severity of food poisoning. Drink a lot in general, eat light foods. Possibly medication (agents against vomiting and diarrhea, antibiotics, antidotes against certain toxins, activated charcoal), possibly pumping out the stomach.
• Prognosis: Food poisoning usually heals on its own within a few days. Serious cases as well as children and the elderly may have to be treated as inpatients. Some forms of food poisoning are life-threatening, for example some mushroom poisoning and botulism.
• Prevention: pay attention to fresh products and hygiene in the kitchen; avoid raw food as much as possible; drink only clean water;

Food poisoning: symptoms & causes

The symptoms of food poisoning (including food infection) can vary slightly depending on the cause. Classic signs that almost always appear are:

• nausea
• Vomit
• diarrhea
• Stomach cramps

In the case of food poisoning, the symptoms usually become noticeable within a few minutes to hours after consuming the spoiled or poisonous food. In rare cases - such as an infection with the Campylobacter bacterium - this so-called incubation period can be several days.

The main symptoms of food poisoning

Food poisoning causes typical symptoms - but not all symptoms need to appear at the same time.

Often the symptoms of food poisoning are only moderate and go away on their own after a few days. Sometimes, however, there is also severe poisoning with very pronounced symptoms such as violent vomiting, very bloody diarrhea or more than ten diarrhea per day. Then you should definitely go to the doctor!

Food poisoning from pathogens

In the case of food poisoning by pathogens (food infection), the exact symptoms depend on the type of pathogen. Important infections are samonellosis, listeriosis and botulism:

salmonellosis

Salmonella poisoning is caused by bacteria from the Salmonella group. The pathogens are usually ingested through raw or insufficiently heated animal foods. The consumption of raw eggs in particular poses a high potential risk. In addition to the symptoms mentioned above, symptoms of salmonellosis are particularly chills and fever. Sometimes, however, an infection with Salmonella is symptom-free.

Listeriosis

This is an infection with bacteria of the genus Listeria. These can be found in animal foods such as raw milk, soft cheese (e.g. Roquefort and Brie) or raw meat. They can also multiply in vacuum packaging. Low temperatures (such as in the refrigerator) do not inhibit the growth of these bacteria.

A Listeria infection usually does not cause any symptoms in otherwise healthy people. When symptoms occur, it is often joint and muscle pain, fever, vomiting and diarrhea. Further complaints are possible if the listeria spread to other organ systems. It is particularly dangerous if they penetrate the brain and cause meningitis there. This manifests itself in a high fever, headache and stiff neck. In addition, the listeria can get into the blood system and cause blood poisoning (sepsis). Inflammation of the inner wall of the heart (endocarditis) or peritonitis (peritonitis) can also be the result of an infection with Listeria.

Infants, the elderly and people whose immune systems have been severely weakened by other diseases or drugs are particularly susceptible to such serious complications. Pregnant women and their unborn child are also particularly at risk: Listeria-related food poisoning in the expectant mother can cause miscarriage or stillbirth.

botulism

This rare but very dangerous infection is caused by bacteria of the type Clostridium botulinum (Clostridia). It usually arises from the consumption of contaminated food - particularly packaged products whose packaging (such as canned food) is bloated are suspect. Self-made canned food and pickled vegetables and fruits are also possible triggers of clostridial food poisoning. Symptoms of the infection affect the nervous system because the bacteria attack it:

The first symptoms of paralysis of the eye muscles appear around 20 to 36 hours after eating foods contaminated with clostridia. Later there is a weakening of the entire skeletal muscles, speech disorders, a slow heartbeat and low blood pressure as well as constipation and urinary retention. A dry mouth, swallowing and vision disorders, dilated pupils, drooping eyelids and decreased reflexes are also typical.

It becomes dangerous when nerves that are responsible for breathing are affected. Without mechanical ventilation, botulism can lead to death from respiratory failure. The patients must therefore always be treated in the hospital.

Other bacterial causes and their symptoms

There are many other pathogens that can be responsible for a food infection. Here are some examples and typical symptoms of the infection:

• Escherichia coli: The E. coli bacterium is found mainly in raw beef and raw milk. Human-to-human transmission is also possible. An E. coli infection initially triggers watery, later bloody diarrhea.
• Staphylococci: These bacteria can get from the hands into the food when handled improperly in the kitchen and thus cause food poisoning (heating the food does not kill the germs). Symptoms are low temperature and poor circulation.
• Yersinia: The bacterium Yersinia is usually transmitted through contact with infected animals or the consumption of contaminated animal food. Common symptoms of illness are headache, chills and fever.
• Campylobacter: The Campylobacter bacterium is mainly found in insufficiently heated poultry meat and products made from raw eggs. It can be killed by cooking food. Symptoms of Campylobacter food poisoning include a high fever, headache, fatigue, and watery diarrhea.
• Shigella: These germs occur more frequently in warm areas with inadequate hygiene standards, where faeces or sewage contaminate food or drinking water. Food poisoning caused by Shigella causes cramping abdominal pain, painful bowel movements, and diarrhea.

Food poisoning from mushrooms

Consumption of poisonous mushrooms (such as toadstool, death cap mushroom) causes fungal food poisoning. Symptoms such as stomach pain, nausea, and vomiting appear soon after the mushroom meal. Other possible symptoms are sweating, chills, dizziness, impaired consciousness, impaired perception, shortness of breath, palpitations and / or disorders of balance. The extent of the symptoms of poisoning depends on the type and quantity of the mushroom toxin ingested.

The alerted doctor should be informed which mushrooms were (presumably) consumed. It is also very helpful if a remnant of the meal or vomit has been saved so that the doctor can analyze these samples.

Symptoms of poisoning can also occur when eating moldy foods. For example, some molds produce aflatoxins, which severely damage the liver.

Food poisoning from fish, mussels, crabs

Fish poisoning can occur after eating fish, mussels (mussel poisoning) or crabs. Sometimes the reason is that the water dwellers have been stored incorrectly or for too long, so that bacteria have multiplied in them, which then trigger symptoms of poisoning.

Food poisoning after a fish meal can also be caused by ciguatoxin. This is a poison (toxin) that is produced by aquatic protozoa that can get into fish through the food chain. Poisoning manifests itself in nausea, vomiting and diarrhea.

Sometimes food poisoning can also be triggered by naturally poisonous fish. These include the puffer fish. They contain the powerful neurotoxin tetrodotoxin. It can paralyze the skeletal and respiratory muscles and thus quickly lead to death! Only when properly prepared are meals made from puffer fish free from the neurotoxin.

Food poisoning from plants

Food poisoning by plant toxins occurs mainly in small children - they often put parts of plants in their mouths out of curiosity and unnoticed by adults. A wide variety of plants produce toxins to protect themselves from predators. They are called poisonous plants if they are poisonous to humans and animals even in small quantities. Examples of poisonous plants and the symptoms of poisoning they cause are:

• Ivy: stomach discomfort and fever in high doses
• Yew tree: circulatory disorders, respiratory paralysis, clouding of consciousness
• Laburnum: paralysis to respiratory arrest
• Angel's Trumpet: Limitation of Consciousness, Heart Failure
• Autumn crocus: nausea, respiratory paralysis
• Lily of the valley: life-threatening cardiac arrhythmias
• Monkshood: hypothermia, cramps, cardiac or respiratory paralysis, death
• Thimble: cardiac arrhythmias, inflammation, nausea, vomiting, visual disturbances, hallucinations
• Henbane: hallucinations, heart problems
• Potato: Poisoning only when the leaves are used as tea or when green potatoes are consumed: diarrhea, respiratory paralysis
• Tomato: Danger of death if the leaves are used as tea

Call an ambulance immediately if you think you or your child has eaten poisonous plants!

Food poisoning from pollutants

If food is contaminated with toxic metals or metal compounds (lead, cadmium, mercury, zinc, etc.), consumption can also cause symptoms of poisoning. This is especially true if someone consumes a large amount or repeatedly consumes smaller amounts of the contaminated food. The type and severity of the symptoms depend on the pollutant and the amount absorbed. For example, organic lead compounds can disrupt the central nervous system and thereby trigger hallucinations, states of excitement and convulsions. Parkinson's-like symptoms and paralysis can also occur as long-term effects.

Food poisoning: risk factors

Food poisoning from pathogens (food infections) often occurs as a local epidemic, for example when the canteen food or the food on a cruise ship is spoiled. Food poisoning of this kind is particularly common in the summer months, as the pathogens multiply faster in warm temperatures.

Some countries are more at risk of food poisoning than others. On the one hand, this is due to different hygiene standards in the cultivation, preparation and sale of food.On the other hand, the climate plays a role: In tropical and subtropical regions there are temperatures at which bacteria can multiply particularly well. For example, vacationers in the Mediterranean region should pay particular attention to adequate hygiene standards in order to avoid food poisoning caused by bacteria.

Viruses can also enter the body through food and cause gastrointestinal complaints. Doctors then do not speak of food poisoning, but of a viral infection, the cause of which is contaminated food. Contamination can result from the food coming into contact with infected feces or contaminated water, or from being prepared by infected people. In addition, the meat and innards of infected animals are possible sources of infection.

Viruses cannot multiply in foods and do not spoil them. However, they can remain infectious for a long time. Food cannot be seen from the outside to determine whether it has been contaminated by viruses. Contamination cannot be recognized by taste or smell either. Ready-to-eat cold dishes such as salads, fruit, desserts and baked goods are particularly dangerous.

Viral gastrointestinal complaints often occur in community facilities such as kindergartens, schools, old people's homes and hospitals.

Food poisoning: common causes and how to avoid them

root cause	Source of danger	prevention
bacteria	raw meat, raw eggs, milk, soft cheese / foods made from raw milk, contaminated drinking water	Store food properly and prepare it under hygienic conditions. Store leftovers of prepared food in a cool place and reheat thoroughly before consumption. Avoid raw foods as much as possible. In countries with poor hygiene standards, only eat boiled, fried or peeled foods and drink only boiled or bottled water; do without ice cubes.
Poisons	Fish, mushrooms, plants	Only eat mushrooms that you know very well. In the case of fish / marine animals and the cold chain between catch and consumption must not be interrupted. Pay attention to smell. If necessary, do without raw fish completely. Avoid poisonous house and garden plants in households with young children. Watch what the little ones put in their mouths.
Metals	Baking powder, processed cheese, coffee creamer, fruit, vegetables, canned food, oysters, fish, mushrooms, cereals, rice products, drinking water	Eat only small amounts of potentially contaminated food (especially applies to children). Wash or peel fruit thoroughly. Inquire about the catching / growing area. Throw away damaged / bloated canned food.
Molds	Rye, barley, dried fruits, nuts, corn kernels (aflatoxin)	Aflatoxin: Only consume products from the EU or tested products. Watch out for mold spots (white to greenish-gray and hairy) on the food. Do not drink from opaque containers.
Viruses (not classic food poisoning, but viral infection)	Faecal contamination of food and drinking water	Peel or wash fruit and field crops (lettuce, tomatoes, etc.) thoroughly. In countries with poor hygiene standards, only eat cooked / fried foods and drink only boiled or bottled water; do without ice cubes.

Food poisoning: treatment

In general, the treatment of food poisoning depends on the cause of the symptoms. Treatment in hospital may be necessary, for example for patients with weakened immune systems or for botulism.

General measures

General tips and home remedies often help with minor complaints. If you have diarrhea, you should drink a lot to compensate for the loss of water and salts. Suitable drinks include water and tea with sugar. An electrolyte solution from the pharmacy is particularly recommended for severe diarrhea. As an alternative (for example when traveling) you can prepare a salt-sugar solution yourself: Add five tablespoons of sugar, one and a half level tablespoons of table salt and a glass of packaged orange juice to one liter of packaged or boiled water. Mix the whole thing and drink it in sips.

Even if you do not feel like eating because of diarrhea and vomiting, you should not go completely without food for long periods if you have food poisoning. In the first few days, doctors recommend easily digestible foods such as rusks, bananas, rice, white bread and broth. On the other hand, you should avoid acidic, difficult to digest and irritating to the mucous membrane (fruit juices, raw vegetables, dairy products, fatty foods, soft drinks, coffee, alcohol, etc.).

After food poisoning symptoms have subsided, it is advisable to be careful about what you eat for some time. The gastrointestinal tract is still affected and it takes some time to fully recover.

Medication and more

In principle, vomiting or diarrhea in the event of food poisoning can be relieved with the help of special medication: antiemetics such as metoclopramide help against nausea and vomiting, antidiarrheal drugs such as loperamide stop diarrhea. However, such drugs are not generally recommended. The purpose of diarrhea and vomiting is to quickly remove the causative agent or toxin from the body. The doctor will therefore only prescribe antiemetics and antidiarrheal drugs in certain cases, such as severe vomiting or more than ten diarrhea per day.

Depending on the cause of the food poisoning, other drugs and therapeutic measures may be used. For example, patients with bacterial food poisoning are sometimes given antibiotics. This applies, for example, to listeriosis and sometimes also to salmonellosis.

Treatment in the intensive care unit is necessary for botulism. The patients receive an antidote (antitoxin) against the botulinum toxin as quickly as possible. They may also have to be artificially ventilated.

Specific antidotes are also available for some mushroom toxins. In addition, in the case of food poisoning caused by fungus, the affected person's stomach is often pumped out.

Sometimes activated charcoal (medicinal charcoal) is also given in the event of food poisoning. It binds bacteria and toxins in the digestive tract. Everything together is then excreted in the stool.

There is evidence that probiotics can shorten the duration of infection-related diarrhea. Probiotics are special microorganisms (such as lactic acid bacteria) that settle in the intestine and can displace diarrhea pathogens. They are added to some foods (such as yoghurt) and offered as capsules and powders.

Food poisoning: prevention

To avoid food poisoning, food hygiene and adequate treatment of the drinking water are essential. Each individual can contribute to this:

• Wash fruits and vegetables thoroughly before eating or preparing them.
• Wash hands, dishes and kitchen utensils thoroughly before, between and after cooking (especially when preparing raw meat or fish).
• Always clean dishcloths and cleaning cloths that are used in the kitchen well and replace them regularly.
• Wear clean clothes and no jewelry when cooking.
• Fry fish and meat dishes well.
• Refrain from consuming raw milk products, raw fish and raw meat.
• Store food in well-sealable containers and at suitable temperatures (e.g. dairy products in the refrigerator).
• Note the expiry date of food.
• Avoid pets, rodents and insects in the kitchen area.
• Dispose of food if pets, insects or rodents (such as rats, mice) have come into contact with it.
• Dispose of packaging and defrost water from meat products immediately.
• Throw away food that tastes strange or unusual.

In order to avoid food poisoning from frozen foods, you should make sure that the cold chain is interrupted as briefly as possible. Bring frozen products home quickly after shopping and use a cooler bag when the outside temperature is higher. Frozen food should be thawed overnight in the refrigerator (not at room temperature). This is especially important with fish, as bacteria multiply well in thawed water and can cause food poisoning. Before cooking, the fish is washed off.

When preparing dishes that contain raw eggs (tiramisu, mayonnaise, etc.), you should take particular care to only use fresh eggs.

Inflated packaging or bulging lids on food cans can indicate contamination with Clostridium botulinum. Such foods must not be consumed under any circumstances, otherwise severe food poisoning (botulism) can occur.

Vacation in southern countries

In some countries the hygiene standards and the drinking water quality are not as good as in this country. This applies to many popular holiday regions in the Mediterranean. Therefore, measures to prevent food poisoning are particularly important there.

In such countries, for example, you should avoid meals that are raw, prepared with water that has not been boiled or that are only served lukewarm in restaurants. It is best to heed the saying: "Peel it, boil it, cook it or forget it!". That means: You should avoid all food that has not been peeled, boiled or fried.

If there are any doubts about the purity of the tap water, you should only use boiled water or drinking water sold in bottles for drinking and brushing your teeth.

Food poisoning: examinations and diagnosis

If symptoms of (suspected) food poisoning such as diarrhea and vomiting do not go away on their own within a few days, you should see a doctor. In the case of very severe symptoms as well as in children and the elderly, a suspicion of food poisoning should generally be clarified by a doctor. In such cases, the loss of fluids and electrolytes through diarrhea and vomiting can quickly become dangerous.

In most cases, the doctor makes the diagnosis of "food poisoning" based on the medical history (anamnesis) and the symptoms. The classic constellation of symptoms (nausea, vomiting, diarrhea, etc.) and the report of the person concerned about the consumption of mushroom dishes or unfamiliar or strange tasting foods or drinks already provide strong indications of poisoning.

In severe cases of food poisoning with severe diarrhea and / or blood in the stool, the doctor will send stool and blood samples to the laboratory in order to have the pathogen determined precisely. If botulism is suspected, it is checked whether the botulinum toxin can be detected in the patient's stool or vomit. Since the result is only known after about 24 hours, but botulism is very dangerous, the appropriate therapy is usually started beforehand to be on the safe side.

Often at the beginning, a special dish (mushroom dish, canned fruit, etc.) is suspected of having caused food poisoning. Then the doctor can send samples of the suspicious foods to a laboratory to detect any pathogens or toxins in them. This can be very important for the treatment (e.g. knowing exactly what the poisonous fungus is).

Reporting requirement

In Germany there is an obligation to report any bacterial food poisoning. The food suspected to be the cause is analyzed by food testing institutes. If the suspicion is confirmed, the contaminated food can be withdrawn from the market (publication of a food warning) in order to avoid further cases of food poisoning. The competent authorities as well as food chains and private individuals can submit suspicious food for analysis.

Food poisoning: course and prognosis

Most food poisoning cases are straightforward. If food poisoning only progresses with diarrhea and without fever or blood in the stool, it usually goes away on its own within a few days. In individual cases, the duration and severity of the symptoms depend on what exactly caused the poisoning (bacteria, toxin, etc.), how much of it got into the body and what the general state of health of the person affected is.

It becomes dangerous if the loss of fluids and electrolytes due to diarrhea and vomiting is not quickly compensated for. This is often the case, especially with young children and the elderly. They usually have to be treated in hospital: Infusions can quickly replace missing fluids and lost salts (electrolytes) in small and old patients.

Botulism is a life-threatening form of food poisoning: if left untreated, around half of the patients die within three to six days as a result of respiratory paralysis.

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