by Brenna M. Brucker, MD, Lexington Medical Center Emergency Department

If you've ever spent a day curled up near the bathroom, dealing with nausea, vomiting, or diarrhea, you've probably asked yourself: Was it something I ate, or did I catch a bug? It's a common question — and while food poisoning and stomach viruses (often called "stomach bugs") share many symptoms, they're caused by different things and may require slightly different care.

Here's how to tell the difference between the two — and what to do about it.

What Causes Each One?

Food Poisoning: Caused by consuming contaminated food or drinks. The culprits can include bacteria (like Salmonella or E. coli) or toxins produced by those microorganisms.

Stomach Bug (Viral Gastroenteritis): Caused by viruses — usually norovirus or rotavirus — that spread from person to person. It's highly contagious and often spreads through shared surfaces, close contact, or contaminated food and water.

Onset of Symptoms

Food Poisoning: Symptoms often hit fast — anywhere from 1 hour to 12 hours after eating contaminated food. Some types can take longer (up to 48 hours), but rapid onset is typical.

Stomach Bug: Symptoms usually appear 12 to 48 hours after exposure to the virus. So if someone around you was sick a day or two ago, and now you're feeling it — that's a clue.

What Each Feels Like

Both food poisoning and stomach bugs can cause:

• Nausea
• Vomiting
• Diarrhea
• Stomach cramps
• Low-grade fever
• Fatigue

But here's the nuance.

Food poisoning might include:

• More intense and sudden vomiting or diarrhea
• Bloody diarrhea (in severe cases)
• Metallic taste in the mouth (with certain toxins)
• Other people who ate the same food got sick, too

Stomach bugs may include:

• Mild body aches
• Runny nose or mild headache (early on)
• Lingering fatigue for a few days after symptoms clear

How Long Does It Last?

Food poisoning usually clears up in 1 to 3 days, though some cases (like listeria or certain bacterial infections) can last longer or require treatment.

Stomach bugs typically last 1 to 4 days, though you might feel weak or tired for several more.

When To See a Doctor

Regardless of the cause, seek medical attention if you experience:

• High fever (>102°F / 39°C)
• Bloody diarrhea or vomit
• Severe dehydration (dry mouth, dark urine, dizziness)
• Symptoms lasting more than 3 days without improvement
• You're in a high-risk group (infants, elderly, pregnant, or immunocompromised)

Prevention Tips

To avoid food poisoning:

• Cook meats thoroughly
• Avoid cross-contamination in the kitchen
• Watch expiration dates
• Be careful with food left out too long (especially at picnics or buffets)

To avoid stomach bugs:

• Wash hands often (especially before eating or cooking)
• Disinfect shared surfaces
• Avoid close contact with anyone who's recently been sick

While both food poisoning and stomach bugs are unpleasant, they usually run their course with rest, hydration, and time. The main differences come down to how quickly symptoms start, how they spread, and who else around you is affected. When in doubt, stay home, stay hydrated, and keep your distance — no one wants to catch what you've got.