Food Poisoning: Causes, Symptoms, and Treatment

By Jenell Decker, MD
Medically reviewed
September 13, 2021

One bout of food poisoning can make you never eat at your favorite restaurant again. If this has happened to you, you’re not alone.

Every year, an estimated 48 million people in the United States, or 1 in 6 Americans, fall victim to a foodborne disease, otherwise known as food poisoning. Although it’s uncomfortable, food poisoning typically isn’t serious. 

While you may blame that medium-rare burger or salad, many things can cause food poisoning.

In this article, we’ll discuss the different types, causes, symptoms, and treatments of food poisoning as well as how to prevent a foodborne illness.

What Is Food Poisoning? 

Food poisoning is a foodborne infection or disease caused by eating contaminated foods.

There are more than 250 foodborne diseases resulting in a variety of infections caused by bacteria, viruses, and sometimes parasites. 

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Types of food poisoning

Of the hundreds of different foodborne diseases, some of the most common types of food poisoning include: 

  • Staph infection: Staph infections typically come from bacteria in uncooked foods such as deli meats, pastries, and puddings. Symptoms begin about 30 minutes to eight hours after exposure. 
  • Vibrio: Vibrio is caused by bacteria in raw or undercooked shellfish. Symptoms often develop within 2-48 hours.
  • Clostridium perfringens: Large roasts of meat, gravies, or precooked foods might contain bacteria that causes clostridium perfringens. This usually comes on suddenly and lasts for less than 24 hours. 
  • Salmonella: Eating raw or undercooked meat, unpasteurized milk and dairy products, and raw eggs, fruits, and vegetables can cause salmonella. Symptoms set in within six hours to six days of exposure. 
  • Norovirus: Fresh produce, leafy greens, fresh fruits, shellfish, and unsafe water can cause norovirus, a contagious viral infection. Symptoms typically begin 12-48 hours after exposure.
  • Botulism: Botulism can occur from improperly canned or fermented foods that cause toxins to attack your body. Symptoms may occur within 18-36 hours after exposure and usually start in the head and move down. 
  • Campylobacter: The most common cause of campylobacter is eating undercooked or raw poultry or anything that’s touched it. This illness typically causes symptoms about 2-5 days after exposure. 
  • E. coli (Escherichia coli): E. coli is a bacteria that can be found in raw meat, raw vegetables, raw sprouts, and unsafe water sources. Symptoms usually begin 3-4 days after exposure and can develop into a life-threatening condition. 
  • Listeria infection: Listeria comes from bacteria in soft cheese, hot dogs, deli meats, smoked seafood, and raw milk. Symptoms set in at around 1-4 weeks, and it can be particularly dangerous to pregnant women and their newborn babies.

What Causes Food Poisoning? 

Food poisoning is caused by consuming contaminated food. Most often, these foods are contaminated by bacteria, viruses, or parasites. 

  • Bacteria: Pathogenic bacteria like e. coli, listeria, and salmonella are the most common cause of food poisoning. In the U.S., salmonella is the largest culprit of food poisoning cases, with nearly a million cases a year. Uncooked foods are at higher risk for bacterial growth because heating or cooking often kills unwanted pathogens living on our food. 
  • Viral: Norovirus, rotavirus, hepatitis A, adenovirus, and astrovirus can all cause viral foodborne illnesses.
  • Parasites: If a food you consume is contaminated by a parasite, the parasite can take up residence in your gastrointestinal tract and cause serious health problems. Common parasitic infections like giardiasis may also occur when traveling to another country. 

Food Poisoning Symptoms

While symptoms vary based on the type of infection you have, common symptoms of food poisoning include:

The following symptoms may occur in more severe cases:

  • Vomiting and inability to keep liquids down
  • Bloody vomit or diarrhea
  • Blurry vision, muscle weakness, or other neurological symptoms
  • High fever (above 102° F)
  • Signs of dehydration such as dry mouth, infrequent urination, or dizziness when standing

If you experience any of these symptoms, contact a doctor and seek medical treatment.

Food poisoning vs stomach flu

While they might present with similar symptoms, food poisoning and the stomach flu are very different illnesses.

The stomach flu is a viral infection, while food poisoning can have a number of different causes.

Food poisoning symptoms can present 30 minutes to 18 hours after exposure, but the stomach bug will often come on 24-48 hours after exposure.

While food poisoning symptoms may become more severe than those of a stomach bug, they often resolve more quickly. Consult with your doctor if you are unsure what may be causing your symptoms. 

Food Poisoning Diagnosis

The best way to diagnose food poisoning is a physical examination by your doctor.

Based on your symptoms and any travel history, they can determine the type of food poisoning you may be experiencing.

With serious cases of food poisoning, they may do a blood test or take a stool sample.

Risk Factors

Certain individuals are at higher risk of severe food poisoning or complications as a result of illness: 

  • Older adults with suppressed immune systems
  • Young children
  • Immunocompromised individuals
  • Pregnant women are an estimated 10 times more likely to get a listeria infection and are at a higher risk of being infected with E. coli, causing hemolytic uremic syndrome.

In rare cases, severe food poisoning symptoms can lead to long-term complications such as kidney disease, neurological damage, or arthritis. 

Treatment 

Usually food poisoning will pass on its own once your body clears itself of the toxins that are making you sick.

It is important to stay hydrated if you are vomiting or experiencing diarrhea.

In cases of severe dehydration, you may need an IV or oral rehydration solutions.

Foods to eat with food poisoning 

If you are experiencing symptoms of food poisoning, it is best to eat plain foods so as to not further upset the stomach.

Consider foods such as crackers, bananas, rice, chicken broth, and toast.

Also keep electrolytes up with sports drinks and watered-down fruit juices. It’s important to nourish yourself well, even after the bout of food poisoning has passed. 

Foods to avoid with food poisoning 

While you are experiencing food poisoning symptoms, it’s best to avoid dairy-heavy and fatty foods, as well as highly seasoned or spicy foods.

Also avoid caffeine, alcohol, and nicotine, as those can further irritate your digestive system. 

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Prevention Tips

The best way to prevent foodborne diseases is to practice food safety:

  • Clean your work surface in the kitchen and wash your hands before and during food preparation to prevent unwanted germs from entering your food and spreading between dishes. 
  • Wash cutting boards and separate raw foods from cooked foods to prevent cross-contamination. 
  • Cook food all the way through, especially when preparing meat, to kill any potentially harmful bacteria. A food thermometer can be particularly helpful for this. 
  • Practice proper food storage. Ensure your refrigerator is kept at a cold temperature, below 40° F, and that you put leftovers in the fridge within two hours of serving.
How quickly does food poisoning kick in?
The incubation period varies depending on the type of food poisoning you’re experiencing. Some symptoms may appear within a couple of hours, while others may take a number of days to take hold.
What are the 4 types of food poisoning?
There are more than 250 foodborne diseases. The four most common types are derived from bacteria, viruses, parasites, or toxins.
Is food poisoning a serious condition?
Food poisoning is not usually a serious condition and will often resolve on its own, however, complications can lead to serious conditions and even hospitalization. If you experience severe food poisoning symptoms, it is important to contact your doctor immediately.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Jenell Decker, MD

Dr. Decker is a family medicine physician who completed her residency at East Carolina University School of Medicine. She graduated medical school from Marshall University School of Medicine.