You get food poisoning from eating food contaminated with bacteria, viruses, or parasites. Stomach flu (medically known as viral gastroenteritis) is usually caused by contact with certain viruses.
This article explains the symptoms, causes, diagnostic tests, and treatments for food poisoning vs. stomach flu.
Symptoms of Food Poisoning vs. Stomach Flu
The symptoms that occur with food poisoning and the stomach flu overlap quite a bit, so it’s important to understand the signs specific to each condition.
The biggest difference between the two illnesses is in the timing:
If you develop symptoms within a few hours of eating, it’s likely to be food poisoning. Stomach flu symptoms typically appear within a day or two after exposure to the virus.
Symptoms of Food Poisoning
The primary symptoms of food poisoning are:
Vomiting Diarrhea (may be bloody, watery, or mucus-like) Nausea Stomach pain and cramping Fever Weakness
Get medical attention for:
Bloody diarrheaTemperature over 102 degrees Fahrenheit (by mouth)Inability to keep liquids downDiarrhea that lasts more than three days
Symptoms of Stomach Flu (Viral Gastroenteritis)
The primary symptoms of stomach flu include:
Vomiting Diarrhea (may be watery) Nausea Stomach pain and cramping Fever Chills Headache Muscle aches
Get medical attention for:
Change in mental state (e. g. , irritability, lack of energy)Diarrhea lasting more than two daysHigh feverFrequent vomitingSix or more loose stools in one daySevere abdominal or rectal painBlack, tarry, or pus-containing stools
Causes of Food Poisoning vs Stomach Flu
You can contract food poisoning and the stomach flu from exposure to germs, but in different ways.
Dark or infrequent urine Dry mouth Dizziness Weakness Confusion Fainting High fever
Causes of Food Poisoning
Food poisoning is caused by eating something that’s contaminated with germs. This is usually bacteria like E. coli (Escherichia coli), Staphylococcus aureus, or Salmonella, but it can also include viruses or parasites.
With food poisoning, you’ll notice that the illness:
Typically occurs within hoursCan be traced to a particular food sourceAffects more than one personHas more severe symptoms than the stomach flu (such as bloody diarrhea and projectile vomiting)
Causes of Stomach Flu
The stomach flu is an infection that attacks your intestines. It’s most often caused by viruses like norovirus in adults or rotavirus in children. But it can also be triggered by other viruses, bacteria, parasites, or toxins.
While other illnesses are transmitted through the air, the stomach flu is transmitted via:
Contaminated food or drinkTouching a surface that’s been infectedPerson-to-person contact with an infected personContact with the vomit or stools of an infected person
Diagnosis of Food Poisoning vs Stomach Flu
A medical diagnosis of food poisoning vs. stomach flu isn’t always necessary, but there are some exceptions.
You should see a healthcare provider right away for diagnosis and treatment if you’re:
An older adultPregnantImmunocompromisedHaving severe or long-lasting symptoms
Most healthy adults don’t need an official diagnosis. But a diagnosis can help steer you toward the right treatments and let you know if you’re contagious.
Diagnosis of Food Poisoning
If you see a healthcare provider for suspected food poisoning, you can expect:
A review of your symptomsGoing over your medical historyPhysical examinationBlood, urine, or stool tests to identify the potential source of infection
Testing is especially important in the case of a community outbreak.
Diagnosis of Stomach Flu
If you go to a healthcare provider with a suspected case of stomach flu, you should expect:
A review of your symptomsGoing over your medical historyPhysical examinationQuestions about your recent whereabouts since you’re more likely to contract the illness in crowded places like daycares or cruise ships
Testing may not be done unless there’s a reason to find out the strain of the virus, such as a viral outbreak in a hospital setting.
If needed, stool tests can be used to diagnose rotavirus, but this isn’t routine. Blood tests or imaging tests would only be performed if another disease or condition is suspected.
Treatment of Food Poisoning vs Stomach Flu
Treating food poisoning and the stomach flu involves similar tactics. As with many viruses, treatment focuses on preventing dehydration and managing symptoms.
For most people, this can be done effectively at home. Treatment options include:
Staying hydrated with fluids like water or electrolyte-rich drinks Slowly incorporating a BRAT diet (banana, rice, apple, and toast) when you’re able to keep food down Getting plenty of rest to help your body heal Using over-the-counter medications like Pepto-Bismol (bismuth subsalicylate) for an upset stomach, Imodium (loperamide) for mild diarrhea, or Tylenol (acetaminophen) for a fever Taking prescription medications like Zofran (ondansetron) or Reglan (metoclopramide) to treat symptoms of nausea and vomiting, if recommended by your healthcare provider
In certain cases of severe food poisoning, your provider may prescribe antibiotics for infections like shigellosis or an antiparasitic for infections caused by parasites.
Prevention of Food Poisoning vs Stomach Flu
Food poisoning generally isn’t contagious from person to person in the way that the stomach flu is, so prevention tips for both illnesses will vary a bit.
Preventing Food Poisoning
Food poisoning generally isn’t contagious, though some forms can be spread through contact with an infected bodily fluid (like when you touch contaminated feces and then touch your mouth).
To prevent food poisoning, you can:
Wash your hands and work surfaces before, during, and after preparing food. Separate raw meat, poultry, seafood, and eggs from ready-to-eat foods. Cook food to the right internal temperature to kill harmful bacteria. Keep your refrigerator at 40 degrees F or below. Refrigerate leftovers within two hours of cooking.
Preventing the Stomach Flu
The stomach flu is very contagious and easily transmitted. You can be contagious before symptoms appear and for days after they’ve gone away. The germs can stay in your stool for two weeks, as well.
To prevent transmission, you can:
Wash your hands often and well with soap and water. Keep your hands away from your mouth and avoid shaking hands during known viral outbreaks. Handle and prepare food safely. Clean and disinfect common surfaces. Wash laundry thoroughly. Stay home and away from other people when you’re sick.
Summary
Food poisoning and the stomach flu can come with similar symptoms, like nausea and vomiting, but they’re different conditions. Food poisoning is caused by food that’s contaminated by bacteria, viruses, parasites, or toxins. The stomach flu is usually caused by norovirus.
Both can typically be treated at home with hydration, over-the-counter medications for symptom relief, and rest. Protect yourself, your loved ones, and your community by practicing good hygiene habits and ensuring foods are prepared and served safely.
If you develop either condition, watch for signs of dehydration. See a healthcare provider if you have a weak immune system, are pregnant or elderly, or you have severe or lingering symptoms.
