What Is Food Poisoning?

Food poisoning is caused by bacteria and, sometimes, viruses or other germs. They can get into the food we eat or the liquids we drink. We can't taste, smell, or see these germs (at least not without a microscope). But even though they're tiny, they can have a powerful effect on the body.

When germs that cause food poisoning get into our systems, they can release toxins. These toxins are poisons (the reason for the name "food poisoning"), and can cause diarrhea and vomiting.

Usually, doctors use "food poisoning" to describe an illness that comes on quickly after eating contaminated food. People often get diarrhea or start throwing up within a few hours after being infected. The good news is, food poisoning usually goes away quickly too. Most people recover in a couple of days with no lasting problems.

In a few cases, severe food poisoning can mean a visit to the doctor or hospital. When people need medical treatment for food poisoning, it's often because of dehydration. Getting dehydrated is the most common serious complication of food poisoning.

What Are the Signs & Symptoms of Food Poisoning?

How food poisoning shows up depends on the germ that caused it. Someone might start to feel sick within an hour or two of eating or drinking contaminated food or liquid. Other times, symptoms may not appear for a number of weeks. In most cases, symptoms will clear up within 1 to 10 days.

Signs that a child might have food poisoning include:

• nausea (feeling sick)
• belly pain and cramps
• vomiting
• diarrhea
• fever
• headache and overall weakness

In rare cases, food poisoning can make someone feel dizzy, have blurry vision, or notice tingling in the arms. In very rare cases, the weakness that sometimes goes along with food poisoning will cause trouble breathing.

What Causes Food Poisoning?

When people eat or drink something that's contaminated with germs, they can get sick with food poisoning. Often, people get food poisoning from animal-based foods — like meat, poultry, eggs, dairy products, and seafood. But unwashed fruits, vegetables, and other raw foods also can be contaminated and make people sick. Even water can cause food poisoning.

Foods and liquids can be contaminated at lots of different points during food preparation, storage, and handling. For example:

• Water that is used to grow food can become infected with animal or human feces (poop).
• Meat or poultry may come into contact with germs during processing or shipping.
• Bacteria can infect foods stored at the wrong temperature or kept too long.
• Cooks or other food handlers can contaminate foods if they don't wash their hands or they use unclean utensils or cutting boards.

People with health conditions (like chronic kidney disease) or weakened immune systems are more at risk of getting ill from food poisoning than people who are in good health.

What Germs Cause Food Poisoning?

Germs that often cause food poisoning include:

Salmonella. Salmonella bacteria are the leading cause of food poisoning in the United States. These bacteria usually get into foods when they come into contact with animal feces. The main causes of salmonella poisoning are eating dairy products, undercooked meat, and fresh produce that hasn't been washed well.

E. coli (Escherichia coli).E. coli bacteria usually get into food or water when they come into contact with animal feces. Eating undercooked ground beef is the most common cause of E. coli poisoning in the United States.

Listeria. These bacteria are mostly found in unpasteurized dairy products, smoked seafood, and processed meats like hot dogs and lunchmeats. Listeria bacteria also can contaminate fruits and vegetables, although that's less common.

Campylobacter. These bacteria most commonly infect meat, poultry, and unpasteurized milk. Campylobacter also can contaminate water. As with other kinds of bacteria, these usually get into foods through contact with infected animal feces.

Staphylococcus aureus. These bacteria (which can be found in meats, prepared salads, and foods made with contaminated dairy products) spread through hand contact, sneezing, or coughing. That means that people who prepare or handle food can spread the infection.

Shigella. Shigella bacteria can infect seafood or raw fruits and vegetables. Most of the time these bacteria spread when people who prepare or handle food don't wash their hands properly after using the bathroom. Sometimes, an infection causes blood in the stool (poop).

HepatitisA. People mostly get this virus from eating raw shellfish or foods that have been handled by someone who is infected. It can be hard to know the source of an infection because people may not get sick for 15 to 50 days afterward.

Norovirus. Norovirus infections spread easily from person to person, especially in crowded settings, like daycares and schools.

Some of these, including Listeria and E. coli, can cause potentially dangerous heart, kidney, and bleeding problems.

When Should I Call the Doctor?

Most cases of food poisoning don't need medical attention, but some do. The most common serious problem from food poisoning is dehydration. A child who is healthy is unlikely to get dehydrated as long as he or she drinks enough liquids to replace what's lost through throwing up or diarrhea.

Call the doctor if your child has any of these symptoms:

• vomiting that lasts for more than 12 hours
• diarrhea with a fever higher than 101°F (38.3°C)
• severe belly pain that doesn't go away after a bowel movement
• bloody feces (diarrhea or regular poop) or bloody vomit
• bowel movements that are black or maroon
• a racing or pounding heart

It's important to watch for signs of dehydration, which include:

• extreme thirst
• making little or no urine (pee)
• dizziness
• sunken eyes
• lightheadedness or weakness

If your family recently been to a foreign country and your child starts having diarrhea or other stomach problems, call your doctor.

Food poisoning (especially dehydration) can be more serious for people with weakened immune systems or health conditions. If your child has a health condition (such as kidney problems or sickle cell disease), call your doctor right away. Pregnant women also should let their doctors know if they get food poisoning as some germs can affect the unborn child.

How Is Food Poisoning Diagnosed?

A doctor will ask about what your child ate most recently and when symptoms began. The doctor will do an exam, and might take a sample of blood, stool, or pee and send it to a lab for analysis. This will help the doctor find out what's causing the illness.

How Is Food Poisoning Treated?

Usually, food poisoning runs its course and kids get better on their own. Occasionally, though, doctors prescribe antibiotics to treat more severe types of bacterial food poisoning. A child with severe dehydration may need to be treated in a hospital with intravenous (IV) fluids.

At-Home Care

Food poisoning usually goes away on its own in a few days. To help your child feel better in the meantime, make sure he or she:

• Gets plenty of rest.
• Drinks liquids to protect against dehydration. Electrolyte solutions work, but anything except milk or caffeinated beverages will do.
• Takes small, frequent sips to make it easier to keep the fluids down.
• Avoids solid foods and dairy products until any diarrhea has stopped.

Do not give over-the-counter anti-diarrhea medicines. These can make the symptoms of food poisoning last longer. When diarrhea and vomiting have stopped, offer your child small, bland, low-fat meals for a few days to prevent further stomach upset.

If symptoms become serious or you see signs of dehydration, call your doctor.

How Can We Prevent Food Poisoning?

Follow these tips to help protect your family from food poisoning:

• Teach everyone in your family to wash their hands well and often, especially after using the bathroom, before touching food, and after touching raw food. Use soap and warm water and scrub for at least 15 seconds.
• Clean all utensils, cutting boards, and surfaces that you use to prepare food with hot, soapy water.
• Don't serve unpasteurized milk or food that contains unpasteurized milk.
• Wash all raw vegetables and fruits that you can't peel yourself.
• Keep raw foods (especially meat, poultry, and seafood) away from other foods until they're cooked.
• Use perishable food or any food with an expiration date as soon as possible.
• Cook all food from animal sources to a safe internal temperature. For ground beef and pork, this means at least 160°F (71°C). For solid cuts of meat, the safe temperature is 145°F (63°C). For chicken and turkey (ground and whole), it's at least 165°F (74°C). Cook chicken eggs until the yolk is firm. Fish generally is safe to eat once it reaches a temperature of 145°F (63°C).
• Refrigerate leftovers quickly, preferably in containers with lids that snap tightly shut.
• Defrost foods in the refrigerator, a microwave, or cold water. Food should never be thawed at room temperature.
• If food is past its expiration date, tastes funny, or smells strange, throw it out.
• If you're pregnant, avoid all raw or undercooked meat or seafood, smoked seafood, raw eggs and products that might contain raw eggs, soft cheeses, unpasteurized milk and juice, patés, prepared salads, luncheon meats, and hot dogs.
• Don't drink water from streams or untreated wells.

If someone in your family gets food poisoning, tell your local health department. Officials there might be able to find the cause and stop an outbreak that could affect others.