Picture this, you have just finished a delicious meal and while you are on your way home nausea sets in. You wonder whether it is just a case of overeating or food poisoning? Maybe it is completely unrelated to the food you just ate and is actually just a stomach virus?
This article will explore the differences between food poisoning and stomach flu—while the symptoms may be similar, the causes and treatments differ and it is important to be able to differentiate between them and understand what is causing your upset stomach.
What Is a Stomach Virus?
The terms stomach flu and stomach virus are used interchangeably both in this article and in popular usage, however the official medical term for this condition is viral gastroenteritis. The Mayo Clinic defines gastroenteritis as “an intestinal infection marked by watery diarrhea, abdominal cramps, nausea or vomiting, and sometimes fever.” As its name indicates, the stomach virus is caused by a virus that can be transmitted from person to person. It is usually not very serious and once a person is struck with the stomach flu, they can expect to recover fully within a few days. While the term “flu” is used, the stomach flu is not the same thing as influenza, or seasonal flu. That type of flu impacts the respiratory system and causes cold symptoms in the nose, throat, and lungs. Gastroenteritis (or stomach flu or stomach virus), on the other hand, affects the stomach and/or intestines.
What Is Food Poisoning?
Food poisoning, also called foodborne illness, is an illness that comes from eating food that has been contaminated by a bacteria, virus or parasite. Food poisoning is extremely common with approximately 48 million people contracting it every year. Luckily, it is rarely serious or fatal, although there are some types of food poisoning such as botulism that require specific and immediate treatment.
Before I go into more details on what causes stomach flu and food poisoning and how to manage or treat them both, it is important to mention that this article discusses acute stomach pain—pain that comes on somewhat suddenly and does not last more than a few days. This is not to be confused with chronic, ongoing stomach pain.
If you experience chronic stomach pain, then you may have irritable bowel syndrome or other illness that requires medical intervention.
The Difference Between Stomach Virus and Food Poisoning
Many symptoms of the stomach flu and food poisoning are the same, but it is important to know which illness you have so that you can make the right treatment decisions and know what to expect. And so you can know whether or not you are contagious or if you need to warn others about a particular food or restaurant.
Stomach flu is caused by a virus while food poisoning comes from contaminated food. This information is not necessarily enough to help you identify what you are suffering from, but there are several key differences to keep in mind:
- Symptoms of food poisoning, while they may be similar to those of stomach flu, tend to be more severe.
- Food poisoning symptoms are likely to start between one and eight hours from the time contaminated food was consumed, while the stomach virus has a 24-48 hour incubation period.
- Stomach bug symptoms usually last 1-3 days (although there can be severe cases that go on for ten days or more) as compared to food poisoning symptoms which can resolve themselves anywhere between a few hours to 1-2 days.
Stomach Virus Symptoms
The main stomach virus symptoms are:
- Watery diarrhea
- Abdominal pain
- Muscle aches and/or headache
- Low-grade fever
- Loss of appetite
With an incubation period ranging from 24-48 hours, you may not be able to pinpoint exactly when you were exposed to the virus, but you can expect the symptoms to last for 1-2 days. Be aware that sometimes the stomach flu can last up to ten days. This is not necessarily a cause for concern, as long as the symptoms are not worsening and you are able to drink enough fluid to replace what your body is losing through diarrhea and/or vomiting.
Food Poisoning Symptoms
The list of food poisoning symptoms below may look familiar as they are very similar to those of the stomach virus. The impact of food poisoning on your system will vary depending on the exact type of bacteria, virus, or parasite that was in your food.
Here are the most common food poisoning symptoms, all of which can range from mild to severe:
- Upset stomach/cramps
The symptoms can appear as quickly as within an hour of eating but, in some cases, can also come on later. If you start experiencing symptoms, think back to what you ate in the preceding hours and consider whether something may have been off.
Causes of Stomach Virus
If you have a stomach virus, you probably caught it from someone else who was infected with the same thing. Perhaps you shared a drink with someone who had the virus or kissed them hello or goodbye. Most stomach bugs are highly contagious even during the incubation period before any symptoms have appeared so it can be very easy to catch something without realizing it. You can even catch it by touching something that an infected person touched if it has any of their saliva, vomit, or stool on it that could contain the virus.
There are a few different viruses that cause the stomach flu, with the most common being norovirus and rotavirus.
- Norovirus: Norovirus is the leading cause of gastroenteritis with up to 21 million cases in the U.S. every year. It is extremely contagious and contact with a minuscule amount of the virus is enough to make a person sick. Because it can remain on surfaces and be resistant to cleaning products, norovirus spreads rapidly in places like schools, cruise ships, nursing homes and anywhere there are many people in close proximity to each other.
- Rotavirus: Rotavirus is more common in children and is easily passed from one child to another if they put their hands or toys contaminated with the virus in their mouths. The virus can be found in an infected person’s stool a few days before they show any symptoms, and up to ten days after the symptoms stop. During all of that time, the virus is easily transmitted through hand-to-mouth contact. Adults are less likely to experience symptoms of rotavirus, or if they do they will probably be mild, but they can still pass the virus on to others.
Different viruses are active during different times of the year. For example, in the Northern Hemisphere both rotavirus and norovirus are most prevalent from October to April. However, there are many viruses that cause gastroenteritis so it is possible to get sick at any time of year.
Causes of Food Poisoning
Food poisoning is caused by consuming food or a beverage that is contaminated with a bacteria, virus, or parasite. The question is, how does the food become contaminated in the first place?
Contamination can happen at any point during the production, processing or cooking of food. Potential causes of contamination include:
- Not being cooked completely (especially meat)
- Food that needs to be kept cold not being stored properly
- Leaving cooked food unrefrigerated for a long time
- Food being touched by someone who is sick and did not wash their hands
- Cross-contamination or spreading of bacteria between food, surfaces and equipment
Certain foods are more susceptible to picking up bacteria and viruses, and are therefore more likely to cause food poisoning. These foods include:
- Unpasteurized milk
- Unwashed raw fruits and vegetables
In addition, there are different food safety standards and requirements in different parts of the world. Particularly in developing and third world countries, it is important to be vigilant about what you eat or drink.
There are six bacteria and viruses that are the most common culprits of food poisoning:
- Campylobacter: This is most often found in unpasteurized milk, poultry, shellfish, and contaminated water. Its main symptom is diarrhea, and it usually lasts between 2-10 days.
- Clostridium perfringens: This bacteria is common in beef, poultry, gravy, and other food that is left too long at room temperature or warmer. It causes diarrhea and stomach cramps, but usually no fever or vomiting, and only lasts 24-hours or less.
- E. Coli: E. Coli can be found in undercooked ground beef, unpasteurized milk and juice, soft cheeses, raw fruits and vegetables, contaminated water (it can be transmitted from drinking it or swimming in it), animals such as cows, sheep, and goats, and the feces of infected people. E. Coli symptoms include severe diarrhea that may be bloody, severe stomach pain, and vomiting, usually with no fever and can last for 5-10 days.
- Listeria: Listeria is found in unpasteurized milk, soft cheeses, raw fruits and vegetables, deli meats, hot dogs, pates, meat spreads, smoked seafood. In most cases, listeria causes fever and diarrhea, and can easily be mistaken for other types of food poisoning. But if the bacteria spreads outside of the gut, it can become invasive listeriosis and causes fever, fatigue, muscle aches, stiff neck, confusion, loss of balance, and convulsions. Listeria is especially dangerous for pregnant women, so if you are pregnant and have these symptoms you should seek emergency care immediately.
- Norovirus: As discussed above, norovirus is a cause of the stomach flu but since it can be transmitted through food, it is also a cause of food poisoning. Norovirus can be found in produce, shellfish, ready-to-eat foods handled by infected people, or any foods that were contaminated by an infected person’s vomit or feces. Symptoms include watery diarrhea, nausea, vomiting, and stomach pain and last for 1-3 days.
- Salmonella: Salmonella is present in vegetables, chicken, pork, fruits, nuts, eggs, beef, sprouts, as well as in reptiles, frogs, birds, and some pet foods and treats. It causes diarrhea, fever, stomach cramps, and vomiting that can last for 4-7 days.
Does it matter what caused my food poisoning?
It may not actually matter which bacteria or virus has caused your food poisoning since, unless it is very severe, there is not much of a difference in treatment. What is important is knowing what foods and circumstances are more likely to put you at risk for food poisoning so that you can take the appropriate precautions.
What You Can Do at Home
When you are sick in bed, you may be wondering how long will this stomach bug last. The good news is that although food poisoning and the stomach flu are rather unpleasant to deal with, a few days of bedrest, drinking plenty of fluids, and eating bland foods should have you back on your feet. The key thing is to avoid dehydration, which can lead to complications. Make sure you drink plenty of water, Gatorade, or another electrolyte solution.
If it is hard for you to keep liquids down, try drinking a few sips every half an hour. Avoid drinking soda or other sugary drinks, as they will not replace the electrolytes that you need. Sucking on ice chips can also keep you hydrated and may feel soothing.
If you are nauseous and vomiting, the thought of food probably doesn’t even appeal to you, but once your appetite returns, try to start eating again. This will aid your body in recovery. Pace yourself and don’t eat too much too quickly, or you just might find yourself back where you started.
Once you are ready to eat, start with foods on the BRAT diet, which are bland and gentle on your still-fragile system.
What is the BRAT diet?
BRAT stands for bananas, rice, apples, and toast. While you do not need to eat only those four foods, the idea is to eat foods that are easy to digest, low in fiber and high in starch so that you can replace the nutrients and calories that you have lost.
Avoid food and drinks that are high in sugar like cookies or soda, as well as high-fat and high-fiber food that can be hard to digest. It’s also a good idea to stay away from dairy products, spicy, or greasy foods until you’ve fully regained your strength.
Stomach Virus Treatment
The home remedies described above will also work for the vast majority of stomach viruses. Because stomach flu is caused by a virus, antibiotics will not be prescribed. If a doctor suspects that there is a bacterial cause then lab tests can be ordered and antibiotics prescribed if necessary.
There are over-the-counter medicines that can be used for stomach flu treatment: you can take acetaminophen or other pain relievers to help reduce fever and ease any aches and pains, or bismuth subsalicylate (commonly known as Pepto Bismol) for nausea and indigestion.
A doctor may prescribe metoclopramide to prevent vomiting or loperamide to stop diarrhea.
Food Poisoning Treatment
Similar to stomach virus, food poisoning treatment is typically just rest and fluids to help avoid dehydration. Your doctor may recommend anti-nausea medication, but it is generally not advised to take anti-diarrheal medicine when you have food poisoning because it could actually prolong the symptoms or even cause complications.
If your food poisoning is a severe bacterial infection or caused by a parasite then antibiotics or other medications will be prescribed depending on your specific case. Pregnant women who contract listeriosis require antibiotics immediately.
As common as stomach viruses and food poisoning are, there are also many easy things you can do to prevent infection.
When it comes to the stomach flu, you can do the following:
- Wash your hands more often than you think is necessary, especially after being in public places
- If you are sick, stay home to avoid infecting others and if you know others who are sick, try to stay away from them
- Don’t share eating utensils or towels
- Keep your bathrooms and other common areas in your home clean and disinfected
- You can also consider vaccinating your babies against rotavirus
To prevent food poisoning, you should:
- Make sure all food preparation surfaces, equipment and your hands are clean
- Cook meats, seafood, and poultry fully
- Refrigerate perishables within an hour
- Discard any food that looks or smells questionable
- Be aware of the restaurants you are eating at—make sure they do not have health code violations
- Pay attention to any food recalls
Symptoms to Watch For
Both the stomach flu and food poisoning are usually not life-threatening and should resolve within a few days. However, there are certain symptoms that you should be aware of that could be a sign of a worsening condition in need of medical attention.
If you have food poisoning, signs that you are getting worse rather than better include:
- Bloody stools or vomit
- Signs of dehydration, like lightheadedness or fast heart rate
- High fever
- Diarrhea lasting more than three days
- Blurry vision
- Numbness or tingling in extremities
Stomach flu that is becoming more severe can cause the following symptoms:
- Bloody stools or vomit
- Vomiting for more than 48 hours (diarrhea can last longer and that is not abnormal)
- Fever higher than 101° F (38.3° C)
- Swollen abdomen
- Increasingly severe stomach pain
- Signs of dehydration
When to See a Doctor
If you fall victim to either the stomach flu or food poisoning, it should resolve itself within a few days. If it doesn’t, however, you may need to see a doctor.
The most common complication from both the stomach flu and food poisoning is dehydration, which can cause serious issues. If you experience signs of dehydration such as decreased or no urination, dry mouth, dizziness and weakness, and you are unable to keep down any liquids then you should speak to your doctor.
In addition, if you experience any of the worsening symptoms described above, including blood in stools, fever, vomiting, or diarrhea lasting more than 72 hours you should also check in with a doctor.
Finally, if you suspect you may have botulism, a very rare but very dangerous type of foodborne illness, contact your doctor immediately. Symptoms include difficulty swallowing, dry mouth, facial weakness, blurred vision, drooping eyelids, trouble breathing, nausea, vomiting, cramps, or paralysis.
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K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.