Food Poisoning: Signs, Symptoms, Causes, Treatment, and Prevention

food poisoning

What is Food Poisoning?

Food poisoning is mostly known as foodborne illness, arises from eating contaminated, toxic, or spoiled food. Most at times the food poisoning might resolve naturally without treatment. Contamination could occur at home when food is poorly being handled or cooked.

The commonest causes of food poisoning are from infectious organisms like viruses, bacteria, and parasites including their toxins. Vomiting, nausea, and diarrhea are one of the major symptoms of food poisoning. During production or processing, food can tend to be contaminated by these infectious organisms or their toxins.

A study from the Centers for Disease Control and Prevention(CDC) shows that 1 in 6 Americans do experience food poisoning yearly.

What is Food?

Food is a substance either in liquid or solid form that consist of essential nutrients like; carbohydrates, proteins, fats and oils, vitamins, mineral salts, and water that provides energy, growth, body-building, and repair of worn out tissues in the body of an organism.

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Symptoms of Food Poisoning

Food poisoning symptoms do not immediately show up but could surface as from an hour to a maximum of 28 days. The source of contamination determines the symptoms of food poisoning. Here are some of the common signs and symptoms of food poisoning:


Severe abdominal pain or cramps

A weakness of the muscles and body

Incessant diarrhea



Loss of appetite

A headache

You can immediately visit your doctor if you experience any of these chronic symptoms:

High fever from 38oC (100.4oF) above

Blurred vision with slurred speech

Incessant diarrhea for more than 72 hours

Severe pain and abdominal cramps

Bloody urine and stool

Symptoms of excessive dehydration such as passing little or no urine, dry mouth, severe weakness, and difficulty in keeping fluids down.

What Causes Food Poisoning?

Contamination of food can occur in the act of production, processing, growing, harvesting, storing, and shipping. The transfer of harmful organisms from one surface to another which is known as cross-contamination is often the cause. Always do wash your hands after handling raw foods to avoid cross-contamination to foods. This is usually found in raw, ready-to-eat foods like vegetables and salads. Harmful organisms are not killed and tend to cause food poisoning since the foods are not cooked. 

The following infectious organisms are the major causes of food poisoning:




  • Bacteria

These are the common causes of food poisoning. They include Escherichia coli, Salmonella, and Listeria. Clostridium botulinum, Clostridium perfringens, and Campylobacter are the other three (3) lesser-known but powerful foodborne illness. Most food poisoning cases in the United State are caused by Salmonella. A study by the Center for Disease Control (CDC) shows that in 1,000,000 cases of food poisoning, approximately 20,000 hospitalizations are all associated with Salmonella infection yearly.

  • Virus

Viral agents tend to cause food poisoning like norovirus which is attributed to over 19 million cases of food poisoning annually. It can also be called Norwalk virus. Other viral organisms are astrovirus, rotavirus, hepatitis A, and sapovirus. Hepatitis A is a lethal viral organism that is mainly spread through foods.

  • Parasites

These organisms causing food poisoning are less common unlike bacteria but are still very deadly when transmitted through food. Parasites are mainly organisms that live inside or on the body of another organism usually referred to as the host. The most common parasite that causes food poisoning in human is Toxoplasma and is mainly seen in a cat litter boxes. Most parasites can live inside the intestine of humans for years without being noticed. Basically, people with a susceptible immune system like newborn babies, pregnant women and older people are prone to sickness when this parasite is found in their digestive tract.

The table below is a quick summary of all the three (3)major causes of food poisoning:

Causative agents Types of microorganism Onset of symptoms Transmission routes and foods affected
Escherichia coli (0157: H7) Bacteria 1-8 days Spread by undercooked meat and fecal contamination of meat during slaughter. It is also found in unpasteurized milk, vegetables, apple cider, and infected water.
Salmonella typhi Bacteria 1-3 days Raw and undercooked egg, meat, poultry, milk. It can be transmitted through infected food handlers and their knives.
Listeria monocytogenes Bacteria 9-48 hours Raw sprouts, ready-to-eat hot dogs and meat, raw milk, unpasteurized soft cheese, refrigerated seafood. It can be transmitted through contaminated water and soil.
Shigella dysenteriae Bacteria 1-2 days Can be spread by an infected food handler. Other sources are seafood and raw, ready-to-eat produce.
Staphylococcus aureus Bacteria 1-6 hours It is transmitted through sneezing, coughing and hand contact on the infected surface. It includes prepared salad, cream sauces, and meat.
Vibrio cholera Bacteria 1-7 days Can be spread through fecal contamination of foods and water. Other sources are infected food handlers.
Vibrio vulnificus Bacteria 1-7 days Transmitted through contaminated sea water. Other sources are shellfish, raw oysters, raw and undercooked mussels.
Clostridium perfringens Bacteria 8-16 hours Mainly transmitted through dish serving. Avoid keeping food hot enough or chilled too slowly. It is found in stews, meats, and gravies.
Clostridium botulinum Bacteria 2-5 hours Baking potatoes in aluminum foil and foods kept at the warm temperature for long are the significant transmission routes.
Campylobacter Bacteria 2-5 hours Fecal contact with meat surfaces leads to contamination.  Contaminated water and unpasteurized milk. It is common in meat and poultry.
Rotavirus Virus 1-3 days This is spread through an infected food handler. Other sources include raw and ready-to-eat produce.
Hepatitis A Virus 28 days It is spread by infected food handlers and contaminated water. Other sources include shellfish, raw, and ready-to-eat produce.
Norovirus (Norwalk virus) Virus 1-2 days It can be transmitted through infected food handlers and contaminated water. Other sources are raw shellfish and ready-to-eat produce.
Giardia lamblia Parasite 1-2 weeks It can be transmitted through infected food handlers and contaminated water. It is common in raw and ready-to-eat produce.

What Are The Risk Factors Of Food Poisoning?

Everyone can be at risk of contracting food poisoning at least once in his or her lifetime. Some greater population tends to be at higher risks than others. Therefore, anyone with a weakened immune system is highly susceptible to food poisoning. Here are the high-risk groups:

Pregnant women

 Pregnant women tend to be more at risk of contracting the infection during food poisoning because their body is trying to cope with changes in metabolism and circulatory system.The baby in the fetus may also fall sick during pregnancy.

Infants and young children

 This makes them be highly susceptible to infections when they consume contaminated food because their immune system is not fully developed as that of an adult. Young children tend to be extremely dehydrated usually in the form of diarrhea and vomiting which may result in death if not properly treated.  

Older adults

 As you get older, your immune system tends to be less effective and may not the response to changes in metabolism and circulatory system rapidly exposing your body to infections.

People with chronic diseases

 Patients with severe diseases like AIDS, heart diseases, liver diseases, diabetes tends to make their immune system reduced and less effective.

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How Does Food Become Contaminated?

Pathogens which are disease-causing organisms are mainly present in almost all the food we consume. It is always advisable to properly cook your food well so that the microorganisms would be killed before you begin eating. Foods mainly consumed raw are a good source of food poisoning because they are not cooked.

Also, fecal contamination of food and water as a result of the food handler not washes his or her hands properly before cooking and after visiting the toilet. Most dairy products, egg, and meat are prone to contamination easily.

Food Poisoning Diagnosis

Accurate symptoms could help doctors diagnose food poisoning more effectively. In some cases, you might be required to perform a test using your blood, on the food you consumed and stool test to be more precise in the case of the food poisoning. Most at times, a urine test is conducted to ascertain whether a person is dehydrated as a result of the contaminated food.

Treatment of Food Poisoning

Food poisoning can be treated at home or in the hospital in the case of chronic issues. When you contract food poisoning quickly drink fluids to hydrate the body. Coconut water and fruit juice can reduce fatigue and restore carbohydrate in the body.

Consult your doctor before taking medications like Pepto-Bismol and Imodium to help you reduce nausea and also control incessant diarrhea. If after taking these medications and you are not relieved, quickly visit a medical specialized in that field for better treatment.

An individual infected with food poisoning should always have adequate rest before and after treatment. In some chronic cases, an individual will be hydrated with intravenous fluid (IV) in the hospital bed.

Diets for People with Food Poisoning

Although you are not advised to eat solid foods until you are through with your diarrhea and vomiting. Here is the list of good foods to eat for an individual diagnosed with food poisoning:



Sport drinks




Potatoes bland

Fruit juice usually diluted


Boiled vegetables

Ginger ale

Broth of chickens

Cooked bottle gourd

Read Also: What to eat after food poisoning

The following foods should be avoided so as not to increase your stomach cramps:

Food having a high content of sugar

Raw sprouts like beans, clover, and alfalfa

Soft cheeses and milk

Fried and spicy foods


Eating of deli meat, luncheon meats, and uncooked hot dogs

Smoking of cigarettes

Fatty foods

Consuming raw or undercooked eggs and fishes

Caffeine drinks like coffee, soda, and some energy drinks

Foods highly seasoned

Prevention of Food Poisoning

The optimal way to prevent food poisoning is to handle your food with clean hands and avoid it being contaminated. The following are the ways to prevent food poisoning:

  • Do cook your foods to a safe temperature: Harmful microorganisms are killed when foods are properly cooked to the right temperature. A food thermometer could be used to detect the right temperature for your cooked foods. It is advisable to make sure shellfish and fishes are thoroughly cooked. Cook turkey and chicken to at least 165oF (73.9oC), cook ground beef to at least 160oF (71.1oC) and cook pork, lamb, and veal to 145oF (62.8oC) 
  • Defrost food effectively in a refrigerator
  • Always wash your hands, food surfaces and cooking utensils: Wash your hands after visiting the toilet before you begin preparing your foods. Learn to handle your foods with a clean hand. Hot soapy water should be used to wash cooking utensils, cutting boards and any other surfaces you use.
  • Never keep raw foods together with ready-to-eat foods to prevent cross-contamination
  • Anything that has had contact with raw products should be properly sanitized before using it to prepare other foods
  • Make sure you wash all fruits and vegetables before eating
  • Perishable foods should be refrigerated immediately usually between 1-2 hours of purchasing
  • Never taste foods you are not sure of its safe preparation, even though it might be appealing to your eyes.
  • Discard foods properly in your waste bin if left uncovered and you were not sure of the safety of the food.
  • Keep refuse or waste bins well covered and clean so as to guide against an individual inhaling harmful toxins from it.
  • Keep your surrounding environments clean at all times .

What Is The Prognosis(Outlook) for People with Food Poisoning?

Food poisoning is not easily distinguished from other common illness since symptoms might look alike. It should be handled with seriousness since it could be life-threatening to young infants, older adults, pregnant women, and their fetuses because of their weakened immune systems.

The interesting part of food poisoning is that people tend to be relieved completely between 5-48 hours. You can learn more about what to eat after food poisoning.

Although food poisoning could be quite unbearable and life-threatening; however the Centers for Disease Control (CDC) says these facts are extremely rare.

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