Is It Stomach Flu or Food Poisoning?

By Tasneem Paliwala, MD

Last night you shared a lovely meal with friends at a local restaurant. Today, your stomach is cramping and you’re overcome by nausea. Eventually, you find yourself spending far too much time in the bathroom. You’re not sure what’s causing your symptoms, but you do know you feel horrible. Is it stomach flu or food poisoning?

The symptoms are similar for both illnesses, and both can result from dining out with friends.

Stomach flu, a general term for any type of gastrointestinal virus, is contagious. Norovirus is the most common form in adults. Using the example of going out to eat, if someone in the restaurant had a stomach virus, such as a dining partner sitting close to you or a restaurant worker who didn’t properly wash their hands prior to preparing or serving food, chances are good that your symptoms are due to stomach flu.

Food poisoning is caused by bacteria or parasites, such as salmonella and E. coli, and can usually be traced back to consuming contaminated food. Even when a restaurant is practicing safe food handling and cooking, bacteria and parasites can be present in foods the restaurant sourced from suppliers.

A good first step in figuring out what’s ailing you is to talk to the people you were with before you became ill to see if any of them are also experiencing symptoms. If you ate the same things from the menu, it may be a case of food poisoning. If someone you were with has the same symptoms, but you ate different things, it could be stomach flu.

The next step is to assess your symptoms and when they began, which may help you determine what you’re suffering from.

Signs and Symptoms of Stomach Flu

Stomach flu, or gastroenteritis, typically presents with one or more of the following symptoms within 24 to 48 hours after exposure:

• Mild to moderate diarrhea.
• Stomach cramping that may be cyclical instead of constant.
• Abdominal bloating.
• Nausea with or without vomiting.
• Low-grade fever under 100° F.

Depending on the strain of virus you have, you may also experience flu- or cold-like symptoms, such as body aches, sore throat, cough, and nasal congestion. Symptoms last at least two days, but usually less than a week. To avoid passing the virus to others, stay home until your symptoms have stopped.

Most cases of stomach flu will resolve on their own without medical intervention. However, if you experience any of the following, you should talk to your doctor right away:

• Signs of dehydration, including dark urine, infrequent urination, dizziness, weakness, extreme thirst, and dry mouth.
• Bloody stools or vomit.
• High fever over 100° F.
• Severe abdominal pain.
• Symptoms lasting longer than a week.

Signs and Symptoms of Food Poisoning

The onset of food poisoning symptoms typically occurs within two to six hours of eating contaminated food when the bacteria begin releasing toxins into the body, but not all symptoms necessarily start at the same time. The rate at which symptoms start is the main difference between food poisoning and stomach flu. Another difference is how long symptoms last, which is usually two to three days.

The most common signs and symptoms are:

• Abdominal cramping or pain
• Diarrhea
• Nausea
• Vomiting
• Low grade fever under 102° F

Similar to stomach flu, food poisoning most often resolves on its own, but you should see a doctor if your symptoms worsen, causing the following:

• Signs of dehydration, including dark urine, infrequent urination, dizziness, weakness, extreme thirst, and dry mouth.
• Bloody stools or vomit.
• High fever over 102° F.
• Diarrhea lasting more than three days.
• Frequent vomiting and inability to keep even liquids down.
• In some cases, antibiotic or antiparasitic medication may need to be prescribed.

Beware of Dehydration

The greatest danger of both food poisoning and stomach flu is dehydration brought on by vomiting or diarrhea. Loss of fluids and electrolytes can lead to extreme dehydration, which can result in hospitalization. It may be difficult to determine what is causing your symptoms, but if you have any condition that causes frequent diarrhea or vomiting, it’s crucial to replace the fluids and electrolytes lost by drinking plenty of water and an electrolyte-rich drink, such as Pedialyte or Gatorade.