• Food Poisoning
• Flu
• Nutrition

Food Poisoning vs. Stomach Flu

Medically reviewed and edited by Kathlene (Katy) Vannoy AANP-C

The U.S. Centers for Disease Control and Prevention estimates that one in six Americans get sick from a foodborne illness each year. When you're feeling under the weather with stomach issues, it can be challenging to determine whether you're dealing with food poisoning or a stomach flu. Both conditions can cause similar symptoms, but they differ in causes, onset times, and treatment methods. Let’s break down what each condition is, how to differentiate them, and the best ways to treat and manage these conditions.

What is Food Poisoning?

Food poisoning refers to the symptoms that occur within three to six hours after eating contaminated food or drinking sources. Bacteria is the primary cause of food poisoning, but it can also be caused by viruses or parasites. While it's possible to spread bacteria like E. coli or salmonella through poor hygiene (e.g., not washing hands after handling contaminated food), transmission through close contact with an infected person is rare. Food poisoning typically lasts between 12 and 48 hours.

While the severity of your symptoms may depend on the type of germ you swallowed, most food poisoning cause common symptoms, including:

• Diarrhea

• Nausea

• Vomiting

• Stomach cramps

• Weakness

You can lower your risk of getting food poisoning by cooking food thoroughly, washing your hands regularly, and avoiding consuming food from unreliable sources.

What is the Stomach Flu (Viral Gastroenteritis)?

Similar to food poisoning, the stomach flu (viral gastroenteritis) can be contracted from bacteria-contaminated food. However, unlike food poisoning, the primary cause of food poisoning is not bacteria. The stomach flu is often caused by a virus, with norovirus and rotavirus being the most common viruses responsible.

The stomach flu is highly contagious and spreads quickly. It shares similar symptoms with food poisoning including nausea, vomiting, stomach cramps, diarrhea, and abdominal pain. Additionally, symptoms of the stomach flu may also include:

• Fever

• Body aches

• Headaches

These additional symptoms occur because the body’s immune response to the viral infection causes inflammation. This leads to systemic symptoms that are not typically seen with bacterial infections like food poisoning.

Unlike food poisoning, these symptoms typically take one to three days to appear after exposure to the virus. 

Stomach flu is often spread through direct contact with an infected person, touching contaminated surfaces, or consuming tainted food or water.

How to Tell the Difference 

Key differences between food poisoning and stomach flu 

The onset time of symptoms, duration of illness, and potential causes and triggers are different  in each condition.

Evaluating potential causes 

Both food poisoning and stomach flu can result from consuming contaminated food or beverages. To help determine the cause of your symptoms, consider asking yourself following questions:

“What have I eaten recently?”

If you responded with any the following, you might be dealing with either food poisoning or a stomach flu:

• Raw or undercooked meat

• Unwashed fruits and vegetables

• Unpasteurized dairy

• Raw seafood 

• Deli meats and hotdogs

• Sprouts 

• Anything outside that may be prepared by an infected person

Since both food poisoning and stomach flu may result from contaminated food, you may want to evaluate other situations.

Stomach flu is more likely to be spread through close contact with an infected person, which is not possible with food poisoning. To assess the cause of your symptoms, you may ask yourself:

"Have I been in close contact with anyone who has been sick with nausea, vomiting, or diarrhea?"

This could include both direct contact with an infected person or consuming food prepared by someone with stomach flu. If your answer is “yes”, you may have contracted a stomach flu and should seek treatment.

Determining when your symptoms began can help distinguish between food poisoning and stomach flu. If you are wondering whether you have food poisoning or stomach flu, you may want to ask:

“When did my symptoms begin and how did they develop?”

If your symptoms started within three to six hours after eating, it’s more likely you’re  experiencing food poisoning. If they began one to three days after exposure to a virus, it may be stomach flu.

When to Seek Medical Help

Some infections that spread through food may be life-threatening. Some people may need to be hospitalized, and some illnesses may lead to other health problems such as meningitis, kidney damage, hemolytic uremic syndrome (HUS), arthritis, brain and nerve damage.

Whether you have food poisoning or are sick with stomach flu, you should seek medical help if you experience severe symptoms, such as: 

• Bloody diarrhea: Presence of blood in stool, which could indicate a serious infection

• Diarrhea that lasts more than 3 days: Persistent diarrhea that doesn't improve, which may indicate a more severe condition

• High fever: Temperature over 102°F

• Vomiting: Inability to keep liquids down due to continuous vomiting, which may lead to severe dehydration

• Signs of dehydration: Symptoms like reduced urination, dry mouth, and dizziness when standing

What to Expect from Your Healthcare Provider

Your healthcare provider may determine whether you have food poisoning or the stomach flu based on your symptoms. If your symptoms are mild and short-lived, testing may not be necessary. However, if your symptoms are intense and get worse, your healthcare provider may require physical examination and laboratory tests.

Physical examination

During a physical exam, your healthcare provider may check for signs of dehydration, abdominal tenderness, and fever. They might also ask about the specific nature of your symptoms, such as the presence of fever or body aches, which are more indicative of a viral infection like stomach flu.

Laboratory tests

In more severe cases or when the cause is unclear, your doctor may recommend specific tests to confirm the diagnosis:

• Stool tests: A stool sample can be analyzed to identify the presence of bacteria, viruses, or parasites. For example, certain bacteria like salmonella or E. coli can be detected in cases of food poisoning, while viruses like norovirus are more common in stomach flu.

• Blood tests: Blood tests can help detect signs of infection, such as elevated white blood cell counts, which may indicate a bacterial infection. They can also check for dehydration or other complications related to the illness.

• Rapid diagnostic tests: For suspected viral infections like norovirus, rapid tests may be used to quickly identify the virus. This helps in the timely diagnosis of stomach flu.

Treatment and Prevention

Food poisoning prevention

Preventing food poisoning involves careful attention to food safety practices. Here are some key tips:

• Cook food thoroughly: Ensure that meats, poultry, and seafood are cooked to the recommended temperatures to kill harmful bacteria.

• Wash hands regularly: Always wash your hands with soap and water before handling food, after using the restroom, and after touching raw meat.

• Store food properly: Keep perishable items refrigerated at the right temperature and avoid leaving food out at room temperature for extended periods.

• Choose reliable sources: Be cautious when consuming food from unfamiliar or untrustworthy sources, especially street vendors or places with poor hygiene practices.

Stomach flu (viral gastroenteritis) prevention

Preventing the stomach flu involves minimizing exposure to viruses and maintaining good hygiene:

• Practice good hand hygiene: Wash your hands thoroughly and frequently, especially after using the restroom, changing diapers, or before eating.

• Avoid close contact with infected individuals: If someone around you is showing symptoms of stomach flu, avoid close contact and do not share utensils, towels, or other personal items.

• Disinfect contaminated surfaces: Regularly clean and disinfect surfaces that may be contaminated, such as doorknobs, countertops, and bathroom fixtures.

• Handle food safely: Even though stomach flu is primarily spread through person-to-person contact, handling food with clean hands and under sanitary conditions can help prevent the spread of viruses.

• Stay home when sick: If you or your child are experiencing symptoms, stay home from work, school, or daycare to prevent spreading the illness to others.

Food poisoning treatment

While it’s difficult to prevent food poisoning, treatment involves oral rehydration and rest. Over-the-counter (OTC) medications can help manage diarrhea. If your food poisoning is caused by certain bacteria (such as listeria), antibiotics may be required. Following the antibiotics course, probiotics may be recommended to help replenish the beneficial bacteria in your digestive system that may have been eliminated. In severe cases, hospitalization for fluid replacement may be necessary.

Stomach flu treatment

Treatment for a stomach flu may also involve oral rehydration and rest. Since antibiotics are ineffective against viruses, treatment for stomach flu typically includes OTC medications for diarrhea or an upset stomach. If your symptoms are severe, hospitalization for fluid replacement might also be necessary.

How Can LifeMD Help?

When dealing with stomach issues, it can be challenging to determine if you're experiencing food poisoning or a stomach flu. LifeMD is here to help you understand and manage the symptoms of both conditions. 

A team of medical professionals is ready to offer a personalized treatment plan and tips to help you recover quickly.

Get started today.

Kathlene (Katy) Vannoy AANP-C

Katy earned her BS in Biology and BA in Chemistry from Southern Methodist University, her BS in Nursing from Barry University, and her Master of Science in Nursing from UNC Charlotte. Katy’s passions include traveling, beaching, and enjoying great food

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