Upset stomach after eating out? Nauseous after slurping a suspicious oyster?
The good news is that foodborne diseases are generally not serious, and often clear up on their own.
In this article, I’ll describe the different types of food poisoning, the causes of foodborne illnesses, and symptoms to watch out for.
Finally, I’ll discuss treatment for foodborne diseases, and when you should see a doctor.
While there are hundreds of foodborne diseases, common types of food poisoning have one of three causes: bacteria, viruses, or parasites.
Each of these categories of food poisoning displays different symptoms, and have their unique causes and risks.
Bacteria-related food poisoning is the most common in the U.S.
There are fewer than 20 different bacterial culprits for food poisoning, though.
The following are some of the most common.
Salmonella infections have been linked to foods including vegetables, meat, nuts, and sprouts.
To prevent salmonella infections, wash your hands after handling livestock or raw meat, and ensure you cook raw eggs and raw meat thoroughly.
Wash utensils and cutting boards after working with raw materials to avoid cross-contamination.
On occasion, salmonella outbreaks may occur at farms or factories and cause widespread illness and recalls.
These are often tracked and announced through the United States Food and Drug Administration (FDA).
In the United States, E. coli (Escherichia coli) is a common cause of diarrhea.
It is often known as “travelers’ diarrhea,” which occurs after contact with bacteria most commonly found in feces and untreated water that may contaminate your food.
Sources of E. coli infections include undercooked meats, soft cheeses, dairy products, raw fruits and vegetables, as well as drinking or swimming in contaminated waters.
After exposure, most people will begin to see symptoms within three to four days, but for some, symptoms can start in as little as one day, or not appear for up to 10 days.
Common symptoms include bloody diarrhea, severe stomach pains, and vomiting.
In severe cases, an E. coli infection can cause hemolytic uremic syndrome (HUS), which can lead to kidney failure and be life-threatening.
Symptoms of HUS include decreased urine output, dark colored urine, and losing pinkness in cheeks and eyelids.
Campylobacter bacteria can be found in raw or undercooked meats, shellfish, contaminated water, fruits and vegetables that have come in contact with animal feces, and unpasteurized cheese and dairy.
Diarrhea (sometimes bloody), abdominal cramps, fever, and vomiting may occur within two to five days of infection.
The best way to prevent campylobacter is to wash fruits and vegetables, ensure you cook your food thoroughly, and avoid raw cheeses.
Shigella infections can result in stomach cramping, fever, diarrhea, and nausea.
Shigella spreads through human fecal matter, and is very contagious—it spreads when someone comes in contact with shigella-infected feces, and then touches their food or mouth, or when someone with shigella prepares food for others.
An infection can also be contracted if contaminated water—like in a swimming pool where someone with shigella has been swimming—is swallowed.
Young children, especially those between 2-4 years of age, and older adults in the hands of a caretaker are at particular risk for infection.
While listeria is not the most common foodborne illness, it can be particularly dangerous.
Listeria monocytogenes, the bacteria that causes listeria, can be found in raw milks and cheeses, deli meats, raw vegetables and fruits, and undercooked poultry, sausage, and hotdogs, as well as shellfish.
Common symptoms of a listeria infection include nausea, vomiting, aches, fever, and sometimes diarrhea.
Pregnant women and those with suppressed immune systems are at higher risk for listeria infections.
For pregnant women, the severe risks include miscarriage, premature birth, and stillbirth.
In rare cases, invasive listeriosis can invade the blood or brain, causing life-threatening symptoms.
Though it accounts for very few cases of food poisoning in the U.S., botulism can be deadly.
The most common source is home-canned foods.
Improperly canned commercial foods, as well as bottled items and honey, can produce toxins that cause botulism.
Symptoms include difficulty swallowing, muscle weakness—especially in the face—doubled or blurry vision, slurred speech, nausea, pain, and diarrhea.
The toxins will sometimes result in muscle paralysis. Generally, symptoms will occur 18 to 36 hours after eating contaminated food.
Make good choices when it comes to home canned and stored goods. Even a common food, like potato salad, has been linked to botulism outbreaks.
Parasites can be transmitted through foods and make a home for themselves in the consumers digestive tract.
Common foodborne parasites include giardia, cyclospora, roundworms, and tapeworms.
These types of parasites are found in undercooked meats and fish, raw sea plants, and raw vegetables that might be contaminated.
Common symptoms include abdominal pain, diarrhea, muscle pain, cough, and weight loss.
Based on your recent travel history, a medical professional might suggest you have been exposed to a parasite.
Some foodborne illnesses are caused by exposure to viruses spread through food.
The most common of these viral infections include hepatitis A and norovirus.
Viral infections can be spread through fresh produce, shellfish, as well as food that’s been touched by infected food workers.
Symptoms of viral foodborne illness include diarrhea, vomiting, nausea, and stomach pain.
Certain viral food poisoning might be confused with the common stomach flu, which is caused by a highly contagious virus.
Though the symptoms are similar, the causes and severity of the two vary.
Speak with your doctor if you are unsure what is causing your symptoms.
Food Poisoning Treatment
Usually food poisoning will resolve on its own without further medical treatment.
It’s important to drink plenty of fluids to replenish your system.
In severe cases, fluids can be received and replenished through an IV to prevent dehydration.
Watch closely for signs of dehydration, like dry mouth or sunken eyes.
Certain types of bacterial food poisoning may require antibiotics.
In severe cases, blood tests or stool samples might be required to determine the cause of your food poisoning.
For discomfort caused by gastroenteritis symptoms, individuals can take an over-the-counter antidiarrheal like loperamide (Imodium) or bismuth subsalicylate (Pepto-Bismol).
An anti-vomiting medication like chlorpromazine may also help symptoms.
After you’ve experienced food poisoning, eat foods that will not further disturb your gastrointestinal tract.
Broths and crackers are good choices. Also, be sure to replenish your fluids often.
When to See a Doctor
Although most bouts of food poisoning will resolve on their own, some severe symptoms and serious complications can develop into life-threatening illnesses.
If you experience any of the following severe symptoms, it is important that you seek guidance from a health care provider immediately:
- Frequent vomiting and inability to keep liquids down
- Bloody vomit
- Diarrhea for more than three days
- High fever with a temperature greater than 100.4 F
- Excessive dehydration signs
- Neurological symptoms like blurry vision, muscle weakness, and tingling
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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.
K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
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Campylobacter: Questions and Answers. (2019).
Shigella — Shigellosis. (2020).
Listeria (Listeriosis). (n.d.)
The Most Common Foodborne Illnesses. (n.d.)
Bacterial Food Poisoning. (n.d.)
Bacteria and Viruses. (2021).
Transmission of Parasitic Diseases. (2021).
Staphylococcal (Staph) Food Poisoning. (2018).