How Do I Know if it’s Food Poisoning or a Stomach Bug?
The moment tummy troubles hit, the first question is always: Was it my dinner, or is it the stomach flu? Katie Collins, NP, UnityPoint Health, is here to help you figure it out. She breaks down the key differences between food poisoning and a stomach bug, covering onset, symptoms and duration. Plus, she gives guidance on how to treat both at home and when you need to see a doctor.
Difference Between Stomach Bug and Food Poisoning
Both food poisoning and a viral stomach bug can cause miserable symptoms like nausea, diarrhea and vomiting. However, timing is one of the biggest clues in identifying which is to blame.
How Fast Does Food Poisoning Start?
Food poisoning is quick to hit and swift to leave.
"It usually presents a lot faster than stomach bugs — within a few hours up to one to two days max," Collins says.
Symptoms last about one to three days.
A viral stomach bug, like norovirus or rotavirus, takes a slower, steadier course. Symptoms begin to appear about one to three days after exposure. Stomach bugs last anywhere from three to seven days, sometimes longer.
Do You Get a Fever with Food Poisoning or a Stomach Bug?
“In food poisoning, a fever is more common with certain bacterial food poisoning organisms, often leading to inflammatory diarrhea (diarrhea with mucus or blood),” Collins says.
A fever can happen with a stomach bug, too, but it's less frequent than with bacterial food poisoning.
"It all depends on the causative organism," Collins adds, explaining that symptoms like fatigue, muscle aches and headaches can be secondary to whichever is making you sick, or they can be due to dehydration and electrolyte imbalances.
Is Food Poisoning Contagious?
It depends entirely on the cause.
Collins says, “If the food poisoning is caused by norovirus, which can be transmitted via contaminated food or from person to person, then yes, it’s extremely contagious. If the cause is bacteria, like Salmonella or Listeria, the illness is generally not contagious in the same way.”
Stomach bugs, however, are well-known for spreading rapidly.
“Norovirus is extremely contagious. The likelihood of transmitting that to other people is very, very high," Collins continues.
"If you have it, the safest assumption is always that you’re contagious."
How to Treat Food Poisoning or a Stomach Bug at Home
The goal for both illnesses is the same: Stay hydrated and rest your gut. Home remedies for a stomach bug and food poisoning are similar, focusing on hygiene and basic selfcare:
- Ensure contaminated food is thrown out and surfaces are sanitized
- Sip fluids regularly to prevent dehydration
- Wash your hands with soap and water for at least 20 seconds
“The single most important step is hydration,” Collins says.
“Appropriate oral rehydration solutions are recommended, such as Pedialyte for food poisoning and stomach bugs. Make sure to follow the guidelines on how much of these solutions to drink each day.”
For over the counter or prescription medication, the following may provide symptom relief:
- Imodium/Loperamide: Can be used for watery diarrhea, but Collins cautions against using it if you have signs of inflammatory diarrhea. "We want to get those bacterial organisms out of your system," she says.
- Pepto Bismol: For food poisoning, but talk to your doctor first, especially if bloody diarrhea is present.
- Zofran: A doctor can prescribe Zofran for a stomach bug to calm severe nausea and vomiting, offering relief from the worst symptoms, but it won't treat the virus itself.
- Probiotics: While the medical research on using probiotics for a stomach bug is mixed, they’re generally considered safe and may help restore the balance of beneficial gut bacteria damaged by the infection.
Before starting any new medication, whether a supplement, prescription or over the counter, talk to your doctor first to ensure it's safe for you.
What to Eat After a Stomach Bug or Food Poisoning
Focus on simple, non-irritating foods for your gut. Bland choices work well when you have an upset stomach, are vomiting or have diarrhea.
The BRAT diet is an easy way to know what foods will agree with you, such as:
- Bananas
- Rice
- Applesauce
- Toast
Other easy and nutritious home remedies for a stomach bug and food poisoning include broth-based soups, boiled vegetables, noodles, potatoes, oats and plain crackers.
What Foods to Avoid After Food Poisoning or a Stomach Bug
Steer clear of anything that’s high in fat, greasy, fried, buttery or spicy. Red meat is another no-go. These foods are tough to digest and can lead to a diarrhea flare-up. It’s also a good idea to avoid foods known to upset your personal brand of GI tract. This varies by person.
Pregnancy and Food Poisoning Risk
Pregnant individuals are at a much higher risk for specific types of food poisoning, most notably Listeria. It can cause severe risk to the fetus, including miscarriage.
Listeria is most commonly found in:
• Deli meats (which should be microwaved for at least 15-30 seconds, if consumed during pregnancy)
• Hot dogs
• Unpasteurized dairy products (soft cheeses)
It’s critical to wash all produce thoroughly and avoid high-risk foods, particularly during pregnancy.
Can You Die from Food Poisoning?
While rare, fatalities are usually related to severe dehydration and electrolyte imbalances, not the organisms themselves.
When to Go to the Doctor for a Stomach Bug or Food Poisoning
While most cases resolve on their own, certain red flags require immediate medical attention:
- Bloody diarrhea: If you have blood or mucus in your stool, you may need stool studies and potentially antibiotics.
- Fever: A temperature over 102 F is a strong indicator of a more serious bacterial infection.
- High-risk groups: Pregnant individuals, children, those who are immunocompromised and anyone over the age of 65 should seek care quickly if symptoms worsen, due to the high risk of dehydration.
- Severe abdominal pain: Persistent or debilitating pain.
- Severe dehydration: This is the biggest risk. Signs include lightheadedness, confusion and significantly darkened or reduced urine output.
"The likelihood of being prescribed an antibiotic is certainly higher if you’re experiencing fever, bloody diarrhea or severe dehydration," Collins says, noting that antibiotics are used to target the bacterial organisms often seen in inflammatory diarrhea.
“Monitor for severe signs like high fever, bloody diarrhea or dehydration,” she adds. For anyone — especially those in a high-risk group — call your doctor if these symptoms appear. A provider can help prevent complications and determine if you need antibiotics.