Food Poisoning

How to know if you have food poisoning or a stomach virus.

What is food poisoning?

Food poisoning is an illness caused by eating contaminated food. The food could have germs that cause infection (like bacteria, viruses, parasites) or toxins created by germs. It can lead to gastrointestinal (digestive tract) symptoms like nausea, vomiting, and diarrhea.

There are many germs and toxins that can cause food poisoning. Campylobacter, E. Coli, Listeria, and Salmonella are some common ones.

Depending on the cause of the food poisoning, you may need to be treated, so it’s a good idea to call your doctor if your symptoms don’t improve in 2-3 days.

What is causing your symptoms?

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Most common symptoms of food poisoning

Pro Tip

Just because other people didn’t get sick doesn’t mean you don’t have food poisoning. —Dr. Shria Kumar

People often have nausea, vomiting, diarrhea, and stomach cramping or pain.

Symptoms can start anywhere from a few hours to even a few weeks after eating contaminated food, though often you’ll notice symptoms within a day or two.

Many of the symptoms are similar to a viral gastrointestinal illness, a “stomach bug” or “stomach flu.” Sometimes, people around you (in your household or who you shared a meal with) may also be having symptoms. This can help narrow down what made you ill. (Though it should be noted, even if others did not get sick, you may still have eaten contaminated food.)

The symptoms last for as long as the infection stays in your system. On the other hand, most viral stomach bugs last only a few days. If it lasts longer than 2-3 days, or you’re weak and dehydrated (very thirsty, decreased urinating, tired, dizzy, feel faint), you need to call your doctor.

Main symptoms

Other symptoms you may have

Mild symptoms

  • Loss of appetite
  • Muscle aches
  • Fatigue
  • General weakness

Symptoms of dehydration

  • Severe thirst
  • Dry mouth
  • Decreased urination
  • Dizziness or feeling like you might pass out.

Risk factors

The biggest risk factor is handling or eating contaminated food. Some foods that are more likely to be contaminated include deli meats, eggs, lettuce, raw or undercooked meat and poultry, raw fruits and vegetables, shellfish, unpasteurized milk.

Some people are also more vulnerable to food poisoning and its complications:

  • Children
  • Elderly people
  • Pregnant women
  • People with a weakened immune system (including those with diabetes, cancer, HIV infection, and sickle cell disease)

Causes of food poisoning

Pro Tip

There are some classic scenarios that we hear with food poisoning—so tell your doctor what happened! Some classic examples are: “I went to a picnic or restaurant and ate ___, then me and someone else got sick in the next few days. Or “I was hiking and drank from a stream.” —Dr. Kumar

Food poisoning is caused by germs (like bacteria, viruses, parasites) or toxins created by germs. Some common bacteria include Campylobacter, E. Coli, Listeria, and Salmonella. Foods can get contaminated at any point including when they are grown (like lettuce), processed, stored (including being left out too long), or during food preparation—in a restaurant, store, or your own kitchen.

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Food poisoning treatment

Treatment depends on what is causing the food poisoning. If it’s caused by a virus, then you need to do the supportive care steps below. The most important one is making sure you stay hydrated, because diarrhea can make you lose fluids quickly.

If it’s caused by a bacteria, the symptoms will be more severe and not get better in 1-2 days. Then you should speak with your doctor. Stool tests can check for bacteria, and if present, will diagnose the type of food poisoning you have. Your doctor will prescribe antibiotics that fight that particular bacteria. Once you start taking the antibiotics, you’ll feel better. You will also need to drink lots of fluids to stay hydrated.

If it’s caused by a parasite, it will also be diagnosed by a stool test and treated with medication.

Regardless of its cause, if you have symptoms of dehydration (see above), you will need fluids by mouth (at home or in a hospital) or through an IV (in a hospital).

Follow this advice until you feel better:

  • Stay home and rest.
  • Drink plenty of fluids.
  • Eat small amounts of food that are bland and easy to digest—crackers, toast, bananas, rice.
  • Avoid dairy products, caffeine, alcohol, nicotine, and spicy foods until you feel better.

Medication

You may be prescribed anti-nausea medications like ondansetron (Zofran) or metoclopramide (Reglan). If you are given antibiotics, remember to take the full course as directed. Hydration is the most important step. Gatorade or other sports drinks, or Pedialyte for children and water are best.

Next steps

Dr. Rx

When food poisoning is caused by a bacteria (as opposed to a virus), the symptoms will be more severe and not get better in 1 to 2 days. Then you should speak with your doctor. Stool tests can check for bacteria. If present, antibiotics will be prescribed. Once you start taking the antibiotics, you’ll feel better. —Dr. Kumar

Call your doctor or go to the ER if you experience any of the following:

  • Vomiting so often that you can’t keep liquids down.
  • Any symptoms of severe dehydration: severe thirst, dry mouth, decreased urination, dizziness or feeling like you might pass out.
  • Anything black or bloody in your vomit or stools.
  • Severe abdominal pain.
  • Fever (>100.8 F).
  • Blurry vision, numbness, or weakness: You could have an electrolyte imbalance.

Any child or elderly adult who you think may have food poisoning should see a doctor.

You should also see a doctor if you have ongoing symptoms that have not gone away within 3 days.

Food poisoning in children

Children are more likely to become dehydrated. They may be given special rehydration drinks—like Pedialyte. Or they may need to be admitted to the hospital to monitor their hydration. Signs of dehydration in children include:

  • Drinking more than usual
  • Decreased urination (peeing less or less often)
  • Urine that is darker than normal
  • General weakness and tiredness
  • Being more tired than usual

If your child has a fever, do not give them aspirin or NSAIDs (like ibuprofen) without first talking to your pediatrician. In some cases, aspirin can be life-threatening.

Prevention

Some strategies to help avoid contaminated food include:

  • Whenever handling food, make sure to wash your hands, utensils, and food preparation surfaces frequently.
  • Make sure food is stored at the right temperature (inside a fridge or cooler if you’re outside). Keep raw meat and fish separate from other foods.
  • Make sure that you are cooking foods to the recommended temperature by checking with a food thermometer.
  • Don’t eat or drink food past its expiration date.
  • Throw food out if you are not sure it’s still good or not.
  • If you are pregnant or have a condition that can weaken your immune system, you may need to avoid certain foods with a higher risk of contamination. Talk to your doctor.
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