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Is it a Stomach Virus or Food Poisoning?

By Dr. Joseph DiFranza
Family Practitioner, Reliant Medical Group

When you are vomiting every hour or going through a bad round of diarrhea, you may not care that much whether you have a stomach virus or food poisoning. However, once you recover you may wonder if you can safely return to your favorite restaurant or barbecue stand again…so it can be valuable to know the difference.

In the United States, the most common cause of a stomach virus (also known as stomach flu) is the norovirus. This is a viral infection that attacks the digestive system (and has nothing to do with the flu virus). Stomach viruses like the norovirus are very contagious and can spread quickly. We’ve all heard the stories about passengers on cruise ships suffering en masse with the norovirus. Unfortunately, people infected with a stomach virus are contagious from the moment they become ill to at least the first few days after they recover. Typical stomach viruses can be spread in a number of ways:

  • Eating food or drinking liquids that have been contaminated with the virus
  • Touching a surface that someone with the infection has touched
  • Having direct contact with someone that has the virus

Stomach viruses can be easily spread through the vomit and stool of infected people, so caretakers should be especially careful and take precautions. Although there are rapid stool tests that can be used to detect the norovirus or rotavirus, your doctor will probably make a diagnosis by asking about your symptoms. Typical symptoms of a stomach virus (also known as gastroenteritis) are:

  • Diarrhea that may be watery or bloody
  • Nausea or vomiting
  • Stomach cramps, muscle aches or weakness
  • A low-grade fever
  • Headaches, as well as light-headedness or dizziness

Food poisoning often causes similar symptoms to a stomach virus, which is why the two conditions often confused. However, food poisoning is caused by consuming food that is contaminated by bacteria, viruses, or parasites. Medical professionals often use the term gastroenteritis to describe both conditions.

The symptoms of food poisoning hit more quickly than those of a stomach virus. While symptoms of a stomach virus can take days to develop, food poisoning symptoms can appear very quickly – within six hours of eating a meal. Food poisoning is usually caused by bacteria. Salmonella and E. coli are two common types of bacteria linked to food poisoning. Usually food poisoning happens to more than one person at a time. (Everyone who eats the contaminated food becomes ill.) Salad greens, eggs, undercooked poultry, dairy products and seafood can easily cause food poisoning if they are not handled properly, whether at home or in a restaurant.

Although the symptoms are similar, there are some ways to tell the difference between the stomach flu and food poisoning.

  • Bloody diarrhea is more likely to be a symptom of food poisoning.
  • Projectile vomiting and stomach cramps are often caused by the norovirus, a type of stomach virus.
  • Stomach viruses take longer to develop but usually go away in about 24 to 28 hours after symptoms begin. Food poisoning often lasts longer.
  • Food poisoning usually affects more than one person and can often be traced to a particular source.
  • A stomach virus is more likely to cause a fever, headache and stomach pain.

Whether you have food poisoning or a stomach bug, the important thing to do is treat it properly. Here are some tips:

  • One of the most important things to do is stay hydrated. Throwing up and suffering from diarrhea means you are losing a lot of fluids. Take small sips of water or broth to stay hydrated. Fluids that contain electrolytes such as sports drinks or coconut water can also be helpful (avoid sugary drinks).
  • If you can safely keep fluids in your system, you can start to eat simple, easy-to digest foods such as toast, crackers, soup, rice and bread.
  • Get plenty of rest. It’s best to cancel any planned activities until you feel better.
  • Don’t take any anti-nausea or anti-diarrhea medication without consulting a medical provider first (some medications can make you feel worse). Adults can take ibuprofen or acetaminophen to relieve symptoms.

Be sure to call your doctor if you have a fever, can’t tolerate liquids, have bloody stools or if your diarrhea is severe or lasts more than three days. If you take a prescription medication for a pre-existing condition but can’t keep it down, you should also contact your doctor.

Is it a Stomach Virus or Food Poisoning?

About Joseph DiFranza, MD

Dr. Joseph DiFranza comes to Reliant Medical Group’s department of Family Practice in Fitchburg with over 30 years of experience in caring for patients. In addition to his work as a primary care physician he is also known around the world for his research on the addictiveness of nicotine and the health dangers of smoking.

Dr. DiFranza believes that proper care is in many ways a negotiation between the doctor and the patient. “As...

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