Food Poisoning Symptoms, Causes and How To Prevent Infection

happens when toxic, spoiled, or contaminated food is ingested by an individual. While food poisoning may be uncomfortable, it is rarely life-threatening. It is actually pretty common and most cases don’t even require hospitalization. According to CDC, about 48 million people experience some kind of foodborne illness every year.

can happen to anyone. But, there are certain groups of people who are more at risk of getting sick after eating contaminated food. These are:

  • pregnant women
  • young children
  • seniors (over 65 years)
  • those who have weak immune systems

Most cases of are mild and go away on their own after a couple of days. However, there are also severe cases that will need hospitalization and medication. It is always best to be aware of your symptoms and know when it is time to go to the doctor for treatment.


The symptoms of will vary depending on the specific kind of infection and its severity. Symptoms will typically appear as early as 1 hour after eating contaminated food. In some cases, it can also take 10 days or more for symptoms to start showing.

will usually include three of the symptoms listed below:

  • stomach cramps
  • diarrhea
  • weakness
  • mild fever
  • vomiting
  • nausea 
  • headaches
  • loss of appetite

Severe cases of will present more alarming symptoms, such as:

  • high fever with a temperature of 101.5°F (or higher)
  • diarrhea lasting three days or more
  • urine in blood
  • difficulty seeing or speaking
  • difficulty keeping fluids down
  • severe vomiting
  • blood in vomit

If you experience any of the symptoms listed above, call your doctor immediately. You may need urgent care and hospitalization.

Food Poisoning Causes

What causes food poisoning?

There are several types of disease-causing germs that can contaminate food. Researchers have found that there are over 250 kinds of foodborne diseases, typically caused by bacteria, viruses, or parasites. Most of these are rare but there are about six foodborne illnesses that are considered the most common causes of food poisoning.


Salmonella is one of the most common causes of food poisoning. Infection occurs when a person eats contaminated food or water.

The most common sources of salmonella bacteria are undercooked or raw chicken and meat, eggs, unpasteurized milk, raw fruits, and vegetables. Aside from food, salmonella can also spread from animals to people and from person to person. 

Symptoms of salmonella infection include diarrhea, stomach cramps, vomiting, and mild fever. Symptoms of this illness typically begin 6 hours to 6 days after exposure and can last for 4 to 7 days.

Salmonella Typhi (Typhoid)

Salmonella Typhi is a bacteria that causes Typhoid fever, a severe type of infection that can be life-threatening. This infection affects the intestinal tract and blood. Unlike Salmonella infection, typhoid fever from Salmonella Typhi is pretty rare. It mostly infects travelers who visit developing countries, where water can be contaminated with sewage.

Symptoms include a sustained fever that can be as high as 103 – 104°F, diarrhea or constipation, stomach pain, headache, weakness, dry cough, and loss of appetite. Some people can also develop rashes on the chest, abdomen, and back.

When left untreated, Salmonella Typhi infection can cause liver damage, heart inflammation, gut damage, and internal bleeding. Typhoid fever has a mortality rate of up to 20% of affected individuals.

E. Coli

Escherichia coli, otherwise known as E. coli, are bacteria that can be found in foods and in the intestines of people and animals. Most strains are harmless and can even help keep your gut healthy but others can cause you to get sick.

Symptoms of E. coli infection include diarrhea, stomach cramps, vomiting, and low-grade fever. These symptoms typically appear 3 – 5 days after exposure to contaminated food or water and can last from 5 – 7 days.

Most E. coli infections are mild but there are some strains that can develop a more severe form of infection that produces “Shiga toxin-producing” E. coli. This type of infection is more dangerous and can lead to more serious complications that cause kidney failure and even death.

Symptoms of STEC infection include lethargy, high fever, decreased frequency of urination, vomiting, fast heart rate, pale-looking skin, confusion, and seizures. Prompt treatment is needed to stop the infection from progressing.


Norovirus, also known as the “winter vomiting bug”, is one of the most common causes of acute gastroenteritis. This illness is caused by a virus and not bacteria. It is very contagious and can easily spread through contaminated water or food. 

The virus can also be contracted from being in close contact with an infected person. Infection mostly happens in closed and crowded environments such as daycare centers, nursing homes, hospitals, public schools, and cruise ships.

Symptoms of the Norovirus include nausea, vomiting, diarrhea or loose bowel movement, stomach pain or cramps, low-grade fever, and muscle pain. Signs of infection usually appear 12 to 48 hours after exposure and can last up to 3 days. 

In some cases, an infected person may be asymptomatic, showing no signs or symptoms. They can still be contagious and spread the virus to others. An infected person can continue to shed the virus in their feces for up to 8 weeks. While the virus is contagious, infection typically clears up on its own without the need for antibiotics or hospitalization.

Hepatitis A

Hepatitis A is another illness that can be contracted through contaminated food or water. This virus is highly contagious and affects the liver of the person infected. The infection is usually short-term and doesn’t cause lasting damage to the liver. However, those who have weakened immune systems may be at risk for more serious liver damage.

Symptoms of Hepatitis A don’t appear until after 2 to 7 weeks from infection. Signs of infection include sudden nausea, vomiting, fatigue, fever, stomach pain (typically located beneath your lower ribs on the right side), loss of appetite, clay-colored stool, dark urine, joint pain, jaundice, and intense itching. Some may not have symptoms at all but still be infected and contagious, while others may get sick for 1- 6 months.

This disease can be preventable by getting a hepatitis A vaccine. A single shot can help stop the virus from progressing if it is given within 2 weeks of exposure.


Listeria is a type of bacteria that thrive in moist environments, water, soil, animals, and decaying vegetation. Foods often linked to listeria outbreaks include raw foods, cheese, undercooked poultry, deli meats, sausages, and seafood.

Eating food or beverages contaminated with this bacteria can cause listeriosis – a serious infection that can attack the bloodstream and brain. It can also affect the joints, chest, and abdomen.

While most cases in healthy individuals are mild, it can be dangerous for pregnant women, people with weakened immune systems, and seniors. If a pregnant woman is infected, the bacteria can reach the baby. This can lead to serious complications like miscarriage and stillbirth.

Symptoms of listeriosis can appear as early as a few hours after eating contaminated food. More severe forms can take up to three months to develop. Mild symptoms include fever, nausea, body aches, vomiting, and diarrhea. More severe infections cause headaches, stiff neck, confusion, high fever, loss of balance, and convulsions.

Food Poisoning Treatment

Treatment for food poisoning will depend on the specific bacteria or virus causing the infection. Most of the time, the issue resolves after a couple days of rest at home. The body naturally gets rid of the bacteria or germ without the need for strong medication.

However, there are certain things you can do to help your body recover faster. Here’s what you can do to ease discomfort:

Help your stomach settle.

Your stomach is busy trying to fight the infection. It would help if you temporarily stop eating solid foods until the vomiting stops and your stomach has settled.

Keep hydrated.

It is important to stay hydrated, especially if you are experiencing diarrhea or vomiting. Take only small sips of water or a healthy broth. It is critical to replenish the fluids that your body has lost. Sports drinks contain electrolytes that help with rehydration.

Eat easy-to-digest food.

When your stomach has settled, ease back into eating with bland and easy-to-digest foods. This will give you the nourishment your body needs without putting your stomach to work too much.

Rest and don’t self-medicate.

Your body needs rest to recover. Getting plenty of rest and sleep makes recovery time quicker. It is not advisable to take over-the-counter pills to stop diarrhea because your body is actually helping you get rid of the harmful germs. 

Some cases may need medication and prompt treatment in a hospital. If you suffer from one or more symptoms of food poisoning and your condition is not getting better after 3 days, you may need to call your doctor.

Treatment of food poisoning may include:

Pain management

To manage abdominal pain and cramping, you may be given pain medication. Medication to treat other symptoms may also be needed.

Replacing lost fluids

Persistent diarrhea results in loss of fluids and minerals that the body needs. If you are dehydrated, you may need to receive salts and fluids through an IV.


Antibiotics will be given to kill the bacterial infection. For more severe cases, antibiotics will be given intravenously for faster treatment. Antibiotics are only given to treat infections caused by bacteria. Those caused by parasites and viruses can’t be treated with antibiotics.


Probiotics can also be part of the treatment for food poisoning. Doctors can recommend taking probiotics to replenish the microbes and good bacteria in your gut. Some probiotic strains are believed to shorten a bout of diarrhea.

How to Prevent Food Poisoning

Food poisoning can be prevented by practicing good hygiene and being careful with what you eat and drink. Here are some helpful tips to minimize the risk of food poisoning:

  • Wash your hands frequently with an antibacterial soap, especially after going to the bathroom or before eating. The WHO recommends to wash hands thoroughly for at least 20 seconds.
  • Store food properly by separating raw meat from ready-to-eat foods. Your fridge temperature should be below 5º C and the freezer should be -15º C or below. 
  • Use different chopping boards for raw meat and other ready-to-eat foods to avoid cross-contamination.
  • Rinse raw fruits and vegetables thoroughly with clean water before serving or eating.
  • Cook food with a temperature of at least 75º C to ensure it is thoroughly cooked. Make sure to cook poultry until meat is white and cook burgers, roasts and sausages until their juices run clear.
  • Avoid eating raw or undercooked meat, especially from cheap restaurants or when you are traveling abroad.
  • Don’t eat foods past their expiration date, even if they still look and smell okay.
  • Avoid soft cheeses, especially when they are sold from farmer’s markets. These are often made from unpasteurized milk. Hard cheeses like cheddar and Swiss are safer.
  • Be careful of eating deli meat straight from the packaging, even if they are labeled as cooked. It is best to reheat them before serving or eating.
  • After buying meat or food from the grocery, make sure refrigerate your items right away when you get home.


Food poisoning is a common illness that happens when contaminated food or beverage is ingested. It can also be contracted through close contact with an infected person, through a parasite, or a virus. Most cases of food poisoning are mild and can clear on their own after a couple of days. However, there are also severe cases that can lead to life-threatening complications. To prevent food poisoning from happening, it is critical to practice good hygiene and to always be cautious of the food and drink you eat. It is best to cook foods thoroughly to kill bacteria and ensure that meat and produce are safe to eat.