Food Poisoning

Definition of Food Poisoning

Foodborne illness occurs when people become sick due to contaminants found in food that is consumed. Other official names include foodborne disease or foodborne infection. More specifically, gastroenteritis refers to infectious diarrhea. Common names for foodborne illness include food poisoning, stomach bug, or stomach flu. The contaminants range in sources from bacteria, viruses, toxins, chemical contamination, and parasites.

The Center for Disease Control and Prevention estimate that 1 in 6 Americans experience at least one case of foodborne illness each year and this includes over 120,000 hospital visits and 3,000 deaths.

For food handlers, you must be knowledgeable to prevent a potential food poisoning outbreak. Some states may require food handlers to go through specific training and certification in demonstrating the knowledge. To find out about your state requirement, please visit our Food Handling States Requirement page.

Food handlers must be educated on various foodborne illnesses that could occur if food is improperly handled. One of the most commonly asked questions is the difference between stomach flu and food poisoning. We are here to answer that specific question today. To find out other food handling topics, visit our Study Guide & Practice Exam sections to best prepare for the test.


Food Poisoning Onset Symptoms and Signs

Onset symptoms of food poisoning range in magnitude but can be broken down into short-term and long-term effects. 

Short-term Effects

  • Upset stomach
  • Nausea
  • Vomiting
  • Diarrhea
  • Dehydration
  • Fever
  • Abdominal cramps and pain


Want to know how long food poisoning lasts? Although many of these symptoms may overlap from cause to cause, onset times may vary. Please refer to the Onset Times section if you are looking for a specific bacterial infection or other contaminants.


Long-term Effects

Most people who come across a food contaminant recover with few problems but some higher risk groups can face everlasting health problems or even death.

  • Kidney Failure
    • Hemolytic-uremic syndrome (HUS) is a result of an infection in the digestive system where toxic substances are produced which destroy red blood cells leading to kidney failure. HUS is the leading cause of kidney failure in children in the United States and it can be caused by some strains of E. coli bacteria.
  • Death
    • Around 3,000 people die every year from illnesses caused by various viruses and bacteria that can be found in food.
  • Brain and nerve damage
    • Guillain-Barré syndrome is a disease that causes a person’s immune system to attack the body’s own nerves. It is estimated that as many as 40% of cases of this disease are caused by the bacteria Campylobacter.
  • Chronic Arthritis
    • A small portion of people who are infected with shigella, salmonella, or campylobacter bacteria may see symptoms including pain during urination, eye irritation, and pain in their joints. These symptoms may last months, years, or it could develop into chronic arthritis.


Most Common Causes of Foodborne Illness

  • Botulism

    • Botulism is a rare disease that is caused by a toxin released by bacteria found in soil. Symptoms generally arise 18-36 hours after consuming contaminated food. If untreated, Botulism may lead to muscle paralysis. Symptoms include:
      • Double and blurred vision
      • Muscle weakness
      • Drooping eyelids
      • Dry mouth
    • Botulism often occurs after consumption of mishandled home-canned fruits or vegetables. For infants and young children, do not feed honey or corn syrup.
    • Contact your doctor if you see signs of Botulism as it is a medical emergency.


  • Campylobacteriosis

    • This is the second most common foodborne illness and it is an infectious disease caused by the bacterium campylobacter. The bacteria comes from raw, unpasteurized milk and raw milk products as well as undercooked meats, animal fecal matter, and contaminated water. Many cases go unreported because most people infected can recover without medical attention. Recovery typically takes two to five days and symptoms include:
      • Diarrhea, possibly bloody
      • Cramps
      • Fever
      • Vomiting
    • If the infected falls under the high-risk population (elderly, pregnant, infant, or weakened immune system), medical attention should be sought out.
    • This illness can be prevented by avoiding raw milk products and cooking meats and poultry thoroughly at safe temperatures.


  • Clostridium perfringens

    • C. perfringens is one of the most common causes of foodborne illness and it is often found in large batch kitchen operations. The bacterium that is the source of this disease grows rapidly in room temperatures and does not need much oxygen to reproduce. It is found in raw meats and poultry and is oftentimes linked to hospitals, schools, nursing homes, and other institutions that must cook food for many people at a time. Onset times range from 6-24 hours after consumption of infected foods and symptoms are:
      • Abdominal cramps
      • Diarrhea
    • Most foodborne illness cases caused by C. perfringens are not life threatening and can be treated with drinking warm water, rest, and eating clean, non-greasy foods for a couple days.
    • Prevent this illness by cooking raw meats thoroughly and storing cooked meats properly and low enough temperatures.


  • Cyclospora cayetanensis

    • Cyclospora is an intestinal illness caused by a parasite found on fresh produced that have come in contact with infected water or soil. Signs of this illness typically arise 7 days after consumption and can last for a few weeks up to months if left untreated. Symptoms include:
      • Watery diarrhea
      • Loss of appetite
      • Fatigue
      • Low fever
      • Bloating
    • If you suspect you have cyclospora cayetanensis, contact your doctor and common treatment with antibiotics will be provided. Also, drink plenty of water and rest.


  • E. Coli

    • E. coli is a group of bacteria that exist in the intestines of all animals including humans. Some strains are dangerous and produce a toxin that is harmful to people and can lead to kidney failure. E. coli is found in feces of contaminated animals, fresh produce that has come in contact with the bacteria, undercooked meats, contaminated water, and areas where agricultural animals may live. Signs of E. Coli infections are:
      • Abdominal pain
      • Moderate to severe diarrhea, sometimes with blood
      • Vomiting
      • Severe e. Coli infections lead to dark-colored urine. If you suspect a severe infection, please contact a health professional.
    • Onset can begin anywhere from 1-10 days after ingestion and the duration of the infection usually lasts up to 10 days. If an infection occurs and it shows no signs of being severe, drink plenty of water and rest.


  • Listeria

    • Listeria is a bacteria found in soil, water, and some animals. Unlike many other bacteria, it can reproduce even in cold temperatures. It is commonly found in ready-to-eat meats, soft cheeses made with raw milk, and cold seafood. Onset time can vary from 3 to 70 days after consuming and illnesses can last up to weeks The symptoms are:
      • Vomiting
      • Diarrhea
      • Stiff neck
      • Fever
    • Some people do not develop symptoms even if they are infected but consult a doctor if you do have continued symptoms and they will treat it with antibiotics. High risk groups such as pregnant women, young children, and the elderly should contact health professionals immediately to be treated.


  • Norovirus

    • Norovirus is the cause of the majority of reported foodborne illnesses in the U.S. It can be transferred through produce or any foods that come across the virus and is very contagious among people who have fecal or vomit matter on their hands. It only takes 12-48 hours for the virus to show symptoms are they are:
      • Vomiting
      • Nausea
      • Diarrhea
      • Stomach pain
    • Because this virus is highly contagious, refrain from cooking or being near food if you have the illness. Keep food preparations clean and cook food thoroughly to prevent this disease. For treatment, rest and plenty of hydration are recommended. Antibiotics will not work on the norovirus as it is not bacteria.


  • Salmonella

    • Salmonella is the name of bacteria that is found in infected eggs, poultry, meat, raw milk, cheese, and some raw plants. It is one of the most common foodborne illnesses in the U.S. and most people who come across the illness recover without going to the hospital. Salmonella onsets in between 12-72 hours and has the following symptoms:
      • Diarrhea
      • Vomiting
      • Stomach pain and cramps
      • Fever
    • Salmonella can cause serious complications with the elderly, young children, and people with chronic illness so please see a doctor if you detect these signs. Otherwise, most healthy adults can overcome the illness with bed rest and lots of fluids. Undercooked poultry and eggs are a major cause of salmonella as is a lack of handwashing while preparing foods and interacting with animals before eating.


  • Shigella

    • Shigella is a family of bacteria that is contagious among people through feces. If someone improperly washes their hands, it can be easily transmitted. It is commonly found in contaminated food, especially foods that are assembled by hand that has raw components such as salads and sandwiches. Incubation periods are usually 1 to 7 days and the illness can last for up to a week. Children are at high risk of contracting shigella because they tend to touch many surfaces and their faces without washing their hands frequently. Symptoms of Shigella are:
      • Stomach cramps
      • Fever
      • Vomiting
      • Diarrhea
    • This illness is often found in childcare facilities and schools and overseas due to foreign contaminated drinking water sources. If you think you have shigella, you should rest and drink water. Most cases are not serious unless you are a high risk group. Preventing shigella requires those who have contracted it to stay away from preparing food and for those around the infected to wash their hands thoroughly and frequently.


  • Vibrio

    • Vibrio bacteria live along coastal waters and flourish during warmer summer months. It is found in contaminated seafood and that is how people come in contact with the bacteria. There are two strains: vibrio vulnificus and vibrio parahaemolyticus. The former is more severe and can cause death in half of the infections. V. vulnificus can also infect people through the bloodstream if you swim in contaminated waters with an open wound. Onset periods for both strains range from a day to a week from consumption of the contaminated food. Symptoms are:
      • Diarrhea
      • Vomiting
      • Stomach pain
    • And in more severe cases:
      • Chills
      • Fever
      • Shock
      • Skin rashes
    • If you get an upset stomach after eating raw or undercooked shellfish and it worsens to the more severe symptoms, contact a health professional immediately. To prevent this illness, refrain from eating shellfish if you are in a high risk group.


Duration and Onset Times

Most foodborne illness cases last less than a week long. However, for specific onset times and duration of illnesses, please refer to the chart below.

Scientific Name Illness Onset Time Symptoms Duration Source
Bacillus cereus B. cereus food poisoning 10-16 hrs Abdominal cramps, watery diarrhea, nausea 24-48 hours Meats, stews, gravies, vanilla sauce
Campylobacter jejuni Campylobacteriosis 2-5 days Diarrhea, cramps, fever, and vomiting; diarrhea may be bloody 2-10 days Raw and undercooked poultry, unpasteurized milk, contaminated water


Botulism 12-72 hours Vomiting, diarrhea, blurred vision, double vision, difficulty in swallowing, muscle weakness. Can result in respiratory failure and death Variable Improperly canned foods, especially home-canned vegetables, fermented fish, baked potatoes in aluminum foil


Perfringens food


8–16 hours Intense abdominal cramps, watery diarrhea Usually 24


Meats, poultry, gravy, dried or precooked foods, time and/or temperature-abused foods
Cryptosporidium Intestinal


2-10 days Diarrhea (usually watery), stomach cramps, upset stomach, slight fever May be remitting and relapsing over weeks to months Uncooked food or food contaminated by an ill food handler after cooking, contaminated drinking water


Cyclosporiasis 1-14 days, usually at least 1 week Diarrhea (usually watery), loss of appetite, substantial loss of weight, stomach cramps, nausea, vomiting, fatigue May be remitting and relapsing over weeks to months Various types of fresh produce (imported berries, lettuce, basil)
E. coli

(Escherichia coli)

producing toxin

E. coli infection

(common cause of

“travelers’ diarrhea”)

1-3 days Watery diarrhea, abdominal cramps, some vomiting 3-7 or more days Water or food contaminated with human feces
E. coli O157:H7 Hemorrhagic colitis

or E. coli O157:H7 infection

1-8 days Severe (often bloody) diarrhea, abdominal pain, and vomiting. Usually, little or no fever is present. More common in children 4 years or younger. Can lead to kidney failure. 5-10 days Undercooked beef (especially hamburger), unpasteurized milk and juice, raw fruits and vegetables (e.g. sprouts), and contaminated water
Hepatitis A Hepatitis 28 days average (15-50 days) Diarrhea, dark urine, jaundice, and flu-like symptoms, i.e., fever, headache, nausea, and abdominal pain Variable, 2 weeks-3 months Raw produce, contaminated drinking water, uncooked foods and cooked foods that are not reheated after contact with an infected food handler; shellfish from contaminated waters
Listeria monocytogenes Listeriosis 9-48 hrs for gastrointestinal symptoms, 2-6 weeks for invasive disease Fever, muscle aches, and nausea or diarrhea. Pregnant women may have a mild flu-like illness, and infection can lead to premature delivery or stillbirth. The elderly or immuno-compromised patients may develop bacteremia or meningitis. Variable Unpasteurized milk, soft cheeses made with unpasteurized milk, ready-to-eat deli meats
Noroviruses Variously called viral gastroenteritis, winter diarrhea, acute nonbacterial gastroenteritis, food poisoning, and food infection 12-48 hrs Nausea, vomiting, abdominal cramping, diarrhea, fever, headache. Diarrhea is more prevalent in adults, vomiting more common in children. 12-60 hrs Raw produce, contaminated drinking water, uncooked foods and cooked foods that are not reheated after contact with an infected food handler; shellfish from contaminated waters
Salmonella Salmonellosis 6-48 hours Diarrhea, fever, abdominal cramps, vomiting 4-7 days Eggs, poultry, meat, unpasteurized milk or juice, cheese, contaminated raw fruits, and vegetables
Shigella Shigellosis or Bacillary dysentery 4-7 days Abdominal cramps, fever, and diarrhea. Stools may contain blood and mucus. 24-48 hrs Raw produce, contaminated drinking water, uncooked foods and cooked foods that are not reheated after contact with an infected food handler
Staphylococcus aureus (MRSA) Staphylococcal food poisoning 1-6 hours Sudden onset of severe nausea and vomiting. Abdominal cramps. Diarrhea and fever may be present. 24-48 hours Unrefrigerated or improperly refrigerated meats, potato and egg salads, cream pastries


V. parahaemolyticus infection 4-96 hours Watery (occasionally bloody) diarrhea, abdominal cramps, nausea, vomiting, fever 2-5 days Undercooked or raw seafood, such as shellfish
Vibrio vulnificus V. vulnificus infection 1-7 days Vomiting, diarrhea, abdominal pain, bloodborne infection. Fever, bleeding within the skin, ulcers requiring surgical removal. Can be fatal to persons with liver disease or weakened immune systems. 2-8 days Undercooked or raw seafood, such as shellfish (especially oysters)



Know what foods pose as the highest risk of getting a foodborne illness and avoid handling these foods wrongly.

  • Animal products that are undercooked or uncooked can lead to bacterial infections if stored at unsafe temperatures. Make sure raw meats, unpasteurized milk products, raw eggs, and raw seafood are kept cool in storage and cooked thoroughly for consumption.
  • Raw fruits and vegetables may have bacteria strains left on the leaves or skin even with washing
  • Bulk prepared animal products such as raw premixed eggs or ground meats come from potentially hundreds of animals. If one animal carries a pathogen, the entire batch is contaminated.


Food Poisoning Treatment and Remedies

For symptoms that do not last more than 5 days, individuals suffering from foodborne illness should:

  • Drink a lot of water to prevent dehydration
  • Eat non-greasy, non-dairy foods to prevent further upset stomach symptoms
  • Use over the counter, non-prescription diarrhea medicine if diarrhea occurs
  • Talk to a doctor if you have:
    • Black or bloody stool
    • High fever
    • High frequency of diarrhea (10+ watery stools within 24 hours)