What’s the Difference Between Food Poisoning and a Stomach Bug?  

An uneasy stomach coupled with nausea and diarrhea can quickly derail your plans – and leave you to wonder: where did this come from? When will it stop?  

It’s easy to blame the last thing you ate for your troubles; or to assume you’ve just caught the latest stomach flu. Although the symptoms of food poisoning and a stomach “bug” are very similar and commonly confused, understanding some of the key differences between them may help you answer these questions and know when it’s time to see a doctor.    

Causes  

Any disease that causes diarrhea with or without vomiting is called gastroenteritis, a technical way of saying that the stomach and intestines are inflamed. This includes both illnesses from food – food poisoning – and stomach bugs or the stomach flu. Influenza, also known as the seasonal flu, is completely different, and only involves respiratory symptoms.  

One key difference between food poisoning and stomach bugs is the root cause:  

• Food poisoning is typically caused by bacteria or parasites, though it could be caused by viruses. The most common causes of food-borne illness in the U.S. are norovirus, Salmonella, Clostridium perfringens, Campylobacter and Staphlococcus aureus.  
• Stomach bugs are caused by viruses. Some of the common causes of the stomach flu are norovirus and rotavirus. 

Anyone can get gastroenteritis, but older adults, young children, pregnant women and individuals with weakened immune systems from medical conditions including diabetes, liver disease, kidney disease, organ transplants, HIV/AIDS and recipients of chemotherapy and radiation treatment are more susceptible. 

Onset after exposure  

Another key difference between food poisoning and a stomach bug is how quickly symptoms develop after being exposed:  

• Symptoms of food poisoning can appear as soon as 30 minutes to two hours after being exposed, but they can take up to one week to appear, depending on the cause.  
• Symptoms of a stomach bug may appear within one to three days after being exposed, depending on the cause.  

Symptoms  

Symptoms of food poisoning and a stomach bug are commonly the same:  

• Diarrhea  
• Fever  
• Nausea  

• Stomach cramps 
• Upset stomach  
• Vomiting  

Recovery 

For most individuals, the exact cause of gastroenteritis may not ultimately matter as recovery can typically be managed at home. The main concern during a bout of food poisoning or a stomach bug is staying hydrated while the body loses a large amount of fluid through diarrhea and vomiting.  

Using electrolyte drinks like Gatorade can help the body rehydrate. For children, watered-down juice, Pedialyte or popsicles can be good options. Start with small sips every couple of hours as your stomach will tolerate it. 

Another difference between food poisoning and a stomach bug is how long the symptoms last:  

• Food poisoning symptoms are typically more severe than a stomach bug and resolve themselves within a few hours to one to two days. 
• Stomach bug symptoms usually last one to three days, but they can last as long as 14 days. 

As you begin to recover, stick to a simple diet. The BRAT diet – bananas, rice, apples, toast – is commonly recommended because it is easy to digest. 

When to see a doctor  

Some symptoms should prompt a visit to a health care provider:  

• Diarrhea lasting longer than three days  
• Blood in diarrhea or stool 
• Severe stomach pain 

• High fever of 104°F in adults and 102°F in children  
• Frequent vomiting and inability to keep liquids down 
• Dehydration. Signs include little to no urine; extremely dry mouth and throat; and dizziness when standing up 

A health care provider will help you determine if your symptoms can be attributed to a virus or to a bacteria or parasite. If food poisoning from bacteria is the cause, there may be an antibiotic prescription available to help you recover.  

Taking over the counter anti-diarrhea medication may hurt more than help during a case of gastroenteritis, especially if it’s from food poisoning. Talk to a health care provider to determine the best course of action for you.  

In severe cases of dehydration, individuals may need to be hospitalized so they can receive fluids through an IV.    

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