Foodborne Illnesses

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Foodborne Illnesses Overview

• What is Foodborne Illness?

  Foodborne illness is often called “food poisoning.” It happens when food or drinks have germs or toxins. Most people get better on their own. Some need medicine, hospital care, or urgent medical help.

Symptoms

• What are the signs and symptoms of foodborne illness?

  Common symptoms include nausea, vomiting, belly pain, diarrhea and fever. Signs may start within a few hours. They may also start days or weeks later. This depends on the germ and the food or drink.

  Some symptoms may suggest a more serious infection. Get medical help now for blood in your stool (poop) or vomit (throw up). Get help for chest pain, abnormal heartbeat, headaches confusion, vision change, or weakness.

  Call a doctor if your temperature is above 100.4°F (38°C) or if you cannot eat, drink, or stay hydrated.

• Can symptoms last a long time?

  Most symptoms go away in a few days. Some symptoms can last for weeks to months. This is less common. Rarely they can last longer.

  Some infections can affect the healthy germs that help keep your body working well. This could cause belly pain, diarrhea, constipation, bloating, or cramping. Some infections can cause long-term problems with skin, nerves, muscles, the heart, or joints. If symptoms last more than 48 hours, talk to a doctor.

Causes

• What causes foodborne illness?

  This page focuses on illness caused by bacteria, viruses and parasites. Food allergies and chemicals can cause similar symptoms. They are not the focus here.

  Bacteria

  • Salmonella: This bacteria is a common cause of foodborne illness. It can be found in poultry, beef, pork, eggs, dairy, fruits and vegetables). It can cause fever. It can also cause diarrhea with blood or mucous and bad belly pain.
  • Campylobacter: This bacteria can lead to serious short and long-term illnesses. It is often linked to dairy products, fruits, vegetables, beef, and pork. It can cause fever, bloody diarrhea and bad belly pain. In rare cases, an infection can cause long-term problems. These may include problems with the joints or nerves. Nerve damage can cause muscle weakness and can be life-threatening
  • Escherichia coli (also known as E. coli): Some types of E. coli bacteria cause watery diarrhea and belly pain. Other types cause bloody diarrhea. Common sources include beef, raw milk, and contaminated fruits and vegetables. Rarely this infection can cause serious kidney or blood clotting problems.
  • Listeria: Listeria infections are most dangerous for babies and older adults. It is also risky during pregnancy and for people with weak immune systems (HIV, cancer, diabetes). It can cause watery diarrhea. During pregnancy, it can lead to miscarriage or early labor. Sources include deli meats, undercooked pork or poultry, produce and seafood. In some patients with serious infection, the bacteria can cause swelling in the brain and spinal cord.

  Viruses

  • Norovirus and Rotavirus:These viruses can cause nausea, vomiting, mild fever, headache, and watery diarrhea. Rotavirus is more common in children. Norovirus is more common in adults. It can spread in restaurants, hospitals, schools, events and cruise ships. Norovirus is the most common cause of infectious diarrhea. These viruses often spread when people do not wash their hands after using the bathroom.
  • Hepatitis A: This virus can hurt the liver. It often spreads when food or water has contact with stool (poop) from a person with the virus. It can cause tiredness, nausea, vomiting, fever and belly pain. More serious signs of liver damage with this virus include dark urine, pale stool, itching, and yellow skin or eyes.

  Parasites

  • Cryptosporidium and Cyclospora: These two parasites can cause diarrhea, fever, and tiredness. They can lead to infections of the liver, bile tract, gallbladder, and pancreas. Cryptosporidium is often found in cattle. People can get it from unsafe water, fresh fruits and vegetables and raw milk, especially if their immune system is weak. Cyclospora can spread through fresh produce such as lettuce, berries and basil and through unsafe water. The symptoms do not usually last too long but sometimes can last for weeks to months.
  • Toxoplasma gondii: This parasite can spread through soil, food or water that has cat stool (poop) in contact with it. Pregnant women should be careful because the infection can pass to the fetus. Food sources can include beef, poultry, dairy, deli meat, and produce.
  • Giardia Lamblia: This parasite often spreads through unsafe water. It can cause belly cramps, bloating and diarrhea. Older adults may have a higher risk. People with some immune problems (low Immunoglobulin A) may also have a higher risk.

Risk Factors

• Who is at risk for acquiring foodborne illness?

  Anyone can get a foodborne illness.

  Some people are more likely to get very sick. This includes young children. It also includes older adults, pregnant women, and people with weak immune systems. People may also be at risk if they have cancer, diabetes, or HIV, an organ transplant, liver disease, alcoholism, or have low stomach acid. Long term use of medication that weakens the immune system can also be at risk.

  People at higher risk should call a doctor if they are worried about symptoms.

Diagnosis

• How is foodborne illness diagnosed?

  Foodborne illness is usually diagnosed based on your symptoms and what happened before you got sick. The cause is not always found, especially if symptoms go away quickly.

  Your doctor may ask you what you ate. They may ask where you ate. They may ask if you traveled, camped, have pets, or ate with other people who got sick.

  Your doctor may order blood or urine tests. They may order imaging tests, an endoscopy, or a stool test. A stool test can find the germ. It can also help public health teams find outbreaks.

Prevention/Treatment

• How can I prevent getting a foodborne illness?
  • Clean: Wash your hands with soap and warm running water for at least 20 seconds. Wash after handling food, using the bathroom, changing diapers, or handling pets and their waste. Wash counters, cutting boards, knives and utensils with warm soapy water. Rinse fruits and vegetables under running water.
  • Separate: Keep raw meat, poultry, seafood and eggs away from other foods. Use one cutting board for these foods. Use another for foods that are ready to eat. Keep these foods apart in your cart, bags, refrigerator and freezer.
  • Cook: Cook food all the way through so it is safe to eat. Use a food thermometer. Do not rely only on color or texture. This is not enough to make sure food is safe. Heat leftovers to at least 165°F (74°C).
  • Chill: Put foods that can spoil in the refrigerator within 2 hours. Keep the refrigerator at 40°F or colder. Keep the freezer at O°F or colder. Thaw and marinate food in the refrigerator. Do not leave it on the counter.

  More food safety information is available at www.foodsafety.gov.

• What foods should high risk individuals avoid?
  • Raw or smoked fish, shellfish, meat, or poultry.
  • Raw milk, unpasteurized juice
  • Soft cheeses such feta, Brie, Camembert, queso blanco, queso fresco. Only eat these if they are made with pasteurized milk.
  • Raw or undercooked eggs or foods that contain them.
  • Hot dogs, dry or fermented sausages, pâtés, meat spreads, and deli meats unless they are heated until steaming hot.
• How are foodborne illnesses treated?

  Most treatment is supportive. This means drinking enough fluids, eating small low-fat meals, and resting. Wash your hands well. Stay home from work or school while you are sick. Some infections can spread to others. Antibiotics are not usually needed. Some bacterial or parasite infections may need antibiotics. Do not take anti-diarrhea medicine, such as loperamide, unless a doctor tells you to use it.

  Get medical help right away for blood in your stool (poop) or vomit.

  Get help for chest pain, abnormal heartbeat. Get help for confusion, vision changes, weakness, muscle paralysis (cannot move or walk), or seeing things that are not there. Call your doctor if your temperature is greater than 100.4°F (38°C) or if you cannot eat, drink, or stay hydrated.

Author(s) and Publication Date(s)

James A. Butler, MD, FACP, CAPT MC USN, and Greg Martin, MD, National Naval Medical Center, Bethesda, MD – Published June 2004.

Ryan M. Kwok, MD, MAJ MC USA, and Mark S. Riddle, MD, PhD, CMDR, National Naval Medical Center, Bethesda, MD – Updated August 2013.

Ami Panara Shukla, MD, FACG, University of Miami, Miami, FL and Claire Jansson-Knodell, MD, Cleveland Clinic, Cleveland, OH – Updated July 2026.

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