What’s the Difference Between Food Poisoning and a Stomach Bug?
While they share symptoms like vomiting and diarrhea, their root causes are different.
Food poisoning and stomach bugs may seem similar because they share symptoms like stomach pain, diarrhea, and vomiting. This can make it challenging to tell them apart.
Both of these terms are used informally and refer to inflammation of the stomach lining and intestines, which is why they have symptoms in common. “The general medical term for both food poisoning and a stomach bug is gastroenteritis,” says Vijay Prabhakar, MD, a gastroenterologist at Providence St. Jude in California.
Despite the similarities in symptoms, the root causes are different. Here’s what you need to know about the symptoms of food poisoning versus a stomach bug, their differences, and treatment options for each.
“Food poisoning is a general reference to infection of the gastrointestinal (GI) tract after the ingestion of food or water that contains bacteria, parasites, viruses, or toxins made by these organisms,” says Dr. Prabhakar. Also known as gastroenteritis, food poisoning leads to symptoms affecting both the GI tract and the entire body, he adds.
Common symptoms of food poisoning include the following:
Diarrhea (with or without blood)
Fever
Headache
Nausea
Stomach cramping and pain
Vomiting
Weakness
“Common pathogens that cause food poisoning are salmonella, campylobacter, and E. coli,” says Neil Parikh, MD, a gastroenterologist and chief innovation officer at GI Alliance in Rocky Hill, Connecticut. “We contract these pathogens by eating contaminated foods.” According to Dr. Parikh, the risk of food poisoning increases under these conditions:
Food is undercooked. Some of the most common causes include raw or undercooked eggs, poultry, beef, fruits, vegetables, shellfish, deli meats, soft cheeses, hot dogs, and sprouts that are contaminated with a foodborne pathogen.
Food isn’t stored properly. Contamination is more likely if food isn't handled safely, isn't cooked to a safe internal temperature, or isn't chilled promptly after cooking or use.
Food preparers didn’t use proper hand hygiene.
The food comes into contact with infected animals or environmental hazards.
The symptoms of food poisoning usually start two to six hours after you’ve eaten contaminated food and get better within 24 to 48 hours.
A stomach bug, also called stomach flu, is an informal term for viral gastroenteritis, an inflammation of the GI tract caused by a viral infection.
Viral gastroenteritis is highly contagious and is transmitted from person to person either directly (from direct contact with an infected person) or indirectly (via objects or food touched by a person with the infection). You should limit your contact with others if you think you have it.
Symptoms of viral gastroenteritis may include the following:
Watery diarrhea that doesn't contain blood
Loss of appetite
Nausea
Periodic muscle aches or headaches
Stomach cramping and pain
Vomiting
“Fever, chills, headache, weakness, or blood in the stool are other possible symptoms,” says Prabhakar. These viruses most often cause this viral gastroenteritis, according to Prabhakar:
Symptoms typically begin 24 to 48 hours after coming into contact with the virus and usually last at least two days.
Both illnesses are forms of gastroenteritis and share some symptoms:
Stomach pain
Nausea and vomiting
Diarrhea
Fever
Weakness
But despite these similarities, they have many differences:
Root Causes Food poisoning is caused by consuming contaminated food or water. It can be transmitted from person to person depending on the pathogen, but it’s typically not as contagious as a stomach bug, which is highly contagious.
Onset of Symptoms Symptoms of food poisoning usually start two to six hours after you’ve eaten contaminated food, whereas symptoms of a stomach bug typically begin 24 to 48 hours after coming into contact with the virus
Length of Illness A stomach bug typically lasts at least two days, while food poisoning usually gets better within 24 to 48 hours
The treatments for both food poisoning and stomach bugs are very similar and include resting at home and drinking plenty of fluids to stay hydrated.
Dehydration can happen quickly with either illness due to fluid loss from vomiting, diarrhea, or a fever. That’s why it’s important to replenish those fluids throughout the day. “Drinking fluids with electrolytes to replenish losses through vomiting and diarrhea is important,” says Prabhakar.
Medications like antibiotics may be helpful in some severe cases of food poisoning caused by bacteria, but they’re not helpful for treating viruses. Both conditions are considered self-limited, meaning you’ll get better as they run their course. If you have diarrhea that isn’t bloody and no fever, your provider may suggest you take loperamide (Imodium A-D) for diarrhea or bismuth subsalicylate (Pepto-Bismol, Kaopectate) for an upset stomach.
When dealing with food poisoning or a stomach bug, you should see a doctor as soon as possible under these circumstances:
You have a persistent high fever of over 102 degrees F.
You have bloody vomit or diarrhea.
You can’t keep anything down.
You have dark urine or lack of urine
You have blurred vision.
You feel confused or delirious.
You are dizzy or lightheaded.
Your symptoms haven’t improved in four days.
You feel dehydrated.
Your abdominal pain is severe.
Food poisoning and a stomach bug have some similar symptoms, including vomiting, diarrhea, fever, and stomach pain.
The main differences between food poisoning and a stomach bug include when symptoms start, how long they last, and the type of virus or bacteria causing the illness.
Treatment for stomach bugs and food poisoning include rest and plenty of fluids to prevent dehydration. Your doctor may suggest medication in some cases.
You may want to see a doctor if you have a persistent high fever, show signs of dehydration, or have other severe symptoms.
