Cold & Flu Flu An Overview of the 24-Hour Stomach Flu What You Should Know About Gastroenteritis By Kristina Duda, RN Kristina Duda, RN Facebook LinkedIn Twitter Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention. Learn about our editorial process Updated on November 08, 2022 Medically reviewed by Jane Kim, MD Medically reviewed by Jane Kim, MD LinkedIn Jane Kim, MD, is board-certified in internal medicine and works as a medical editor and writer. She consults on digital content for physician medical education and is based in New York. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Symptoms Causes Diagnosis Treatment When to Get Help Frequently Asked Questions A stomach bug is known for its symptoms of nausea, vomiting, and diarrhea, and you may have called it something like the "stomach flu." It's actually gastroenteritis, an inflammation commonly caused by an infection like norovirus. Most cases are easily treatable, but stomach bugs are highly contagious. It's also unlikely that what you think of as a "24-hour bug" will always resolve that quickly, and when symptoms last longer than that you should call your healthcare provider. This article discusses stomach bug causes, diagnosis, and treatment. It details why these illnesses are not the flu, along with some strategies to prevent them from happening in the first place. Catherine McQueen / Getty Images Stomach Bug Symptoms A stomach bug is really an infectious diarrhea, so that's a main symptom of gastroenteritis. It's caused by the inflammation in your stomach and gastrointestinal tract (digestive system). Gastroenteritis also leads to other symptoms that include: Abdominal pain and cramps Nausea Vomiting Fever Chills Headache A stomach bug generally comes on suddenly and hits hard. The symptoms then gradually decrease as you get better. Symptoms of Stomach Flu Stomach Bug Causes The stomach flu can be caused by a lot of things, including viruses, bacteria, and parasites. Common Viral Causes Stomach bugs are often caused by viruses. The typical culprits include: Rotavirus: Most common in babies between 3 months and 15 months old Adenovirus: Most common in children under 2 Norovirus: Most common cause of adult cases Astrovirus: Affects all ages; typically known for mild infections in children, but researchers are finding strains that affect the nervous system and may lead to life-threatening complications. Most Common Stomach Bug About 60% of all stomach flu cases in the United States are due to norovirus. That comes out to around 21 million norovirus infections each year. Viruses that cause stomach bugs are extremely contagious and easily passed from person to person. The fecal-oral route (from not washing hands after defecating, changing diapers, digging in contaminated soil, etc.) is the primary mode of transmission, with the following also playing a role: Direct contact with a sick personAerosolized (airborne) particles from vomitConsuming contaminated food and waterSurfaces contaminated with norovirus Symptoms may last for just a day or two, or they may continue for more than a week. Common Bacterial Causes Bacterial causes of stomach flu include: Campylobacter Escherichia coli (E. coli) Salmonella Bacteria-associated gastroenteritis is primarily related to something you ate. Campylobacter strains account for around one-third of all bacterial cases. Many of these infections are transmitted through contaminated poultry or other tainted foods, including meat, produce, and dairy products. Symptoms may last for between one and 10 days. Common Parasitic Causes Stomach bugs are less commonly caused by parasites. The primary culprits are: Giardia Cryptosporidium The parasites are spread through food, water, or soil that's contaminated with infected feces. These cases may last longer than is typical of viral or bacterial stomach flu, with symptoms lasting between two and six weeks. Stomach Flu Causes and Risk Factors Is a Stomach Bug Really the Flu? When describing a stomach bug, "flu" is a misnomer. In medical terms, the flu (influenza) is a common viral respiratory infection. It involves symptoms such as: Fever Chills Muscle aches Cough Congestion Sore throat Body aches Fatigue Headaches When you get a flu vaccine, this is what you're being protected from—not gastroenteritis. Stomach Flu AKA gastroenteritis, infectious diarrhea Gastrointestinal infection that can be caused by a virus, bacterium, or parasite Spreads through person-to-person contact, contaminated food or water, or contact with infected feces Symptoms include vomiting, diarrhea, fever, and stomach pain Vomiting usually lasts 24 hours; diarrhea may continue for several days Most can't be prevented with a vaccine Flu AKA seasonal influenza Upper respiratory infection caused by a virus Spreads through droplets in the air caused by coughing or sneezing Symptoms include fever, chills, muscle aches, cough, and congestion May last from two to 10 days May be prevented with a yearly vaccine Diagnosing Stomach Bugs You may know the cause of your stomach flu before even seeing a healthcare provider, especially if, for example, you and several others get sick after eating at a restaurant. If symptoms aren't severe and only last a few days, you likely won't need medical attention. If you do see a healthcare provider, they may diagnose gastroenteritis just from the symptoms and circumstances you describe. They'll also likely be aware of anything that's spreading through the community. In severe or prolonged cases, your provider may need more information. They may order: Blood tests Stool tests Those tests should reveal whether the cause is viral, bacterial, or parasitic, which can guide treatment recommendations. Is It COVID-19? Sometimes COVID-19 can cause gastroenteritis-like symptoms. In some people, these symptoms may be present even if respiratory symptoms aren't. Treating Stomach Bugs Stomach bug symptoms usually go away on their own. The main focus of treatment is to prevent dehydration due to fever, vomiting, and diarrhea. Verywell / Emily Roberts Supportive therapies may include: Rehydration with water or electrolyte-rich sports drinks (avoid sugary sodas and fruit juice) A BRAT diet (banana, rice, apple, and toast) to ease a queasy stomach and stop diarrhea Anti-nausea medicines like Reglan (metoclopramide) or Zofran (ondansetron) to reduce vomiting and lessen the risk of dehydration Anti-diarrheal medication like Pepto-Bismol (bismuth subsalicylate) or Imodium (loperamide); don't use these in children or if you have bloody stools Tylenol (acetaminophen) to relieve fever; other over-the-counter fever reducers (ibuprofen, naproxen, aspirin) are more likely to upset your stomach Antibiotics can be prescribed to help clear up a bacterial or parasitic infection that's caused the gastroenteritis. However, they're ineffective against viruses that commonly cause infection. Stomach Bug Prevention You're better off preventing gastroenteritis than treating it. Frequent hand washing, especially after using the toilet, and good food hygiene help to prevent the transmission of stomach flu. How to Prevent the Stomach Flu When to Call a Healthcare Provider If you are pregnant, immunocompromised, over age 65, or recently hospitalized or on antibiotics, you should contact your healthcare provider for advice. Call your healthcare provider immediately or go to the emergency room if you have: Vomiting for more than 24 hours Diarrhea for several days Violent vomiting Blood in your vomit or stool Trouble keeping fluids down Signs of severe dehydration (no urine for more than eight hours, dizziness, weakness, confusion, fainting, fever over 101 degrees F) When to See a Doctor for Vomiting Summary A stomach bug is spread by contaminated food or water. It's also transmitted through person-to-person contact. It is not the same as the flu (influenza). Common symptoms of the stomach bug include fever, abdominal distress, nausea, vomiting, and diarrhea. Sometimes, stomach flu may go away after 24 hours. But it may take up to 10 days before you fully recover. Treatments may involve antibiotics, medications to stop vomiting and diarrhea, and good hydration. Get medical help for severe symptoms. Frequently Asked Questions How long does gastroenteritis last? Despite the nickname "24-hour stomach flu," most cases of gastroenteritis last longer than a day. Depending on the cause, stomach flu can linger for up to 10 days. Learn More: How Long Should You Stay Home With Stomach Flu? What happens inside your body when you have a stomach bug? In most cases, viruses, bacteria, or other microbes invade your intestine, producing toxins that cause vomiting, diarrhea, inflammation, and other symptoms. Learn More: Causes of Infectious Diarrhea Do crackers help stomach flu? Yes, eating saltine crackers can help to prevent dehydration and maintain electrolytes in your body.Mashed potatoes, bananas, and broths are other foods that may help with symptoms. Learn More: Stomach Flu Remedies 20 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. National Institutes of Health, U.S. National Library of Medicine: MedlinePlus. Gastroenteritis. Johns Hopkins Medicine. Understanding viral gastroenteritis. Vu DL, Bosch A, Pintó RM, Guix S. Epidemiology of Classic and Novel Human Astrovirus: Gastroenteritis and Beyond. Viruses. 2017 Feb 18;9(2):33. doi: 10.3390/v9020033. Robilotti E, Deresinski S, Pinsky BA. Norovirus. Clin Microbiol Rev. 2015;28(1):134-64. doi:10.1128/CMR.00075-14 Johns Hopkins Medicine. Bacterial gastroenteritis. Facciolà A, Riso R, Avventuroso E, et al. Campylobacter: from microbiology to prevention. J Prev Med Hyg. 2017 Jun;58(2):E79-92. Medical University of South Carolina: MUSC Health. Gastroenteritis. Centers for Disease Control and Prevention. Parasites - giardia. Centers for Disease Control and Prevention. Influenza (flu): What you need to know. Centers for Disease Control and Prevention. Influenza (flu): Misconceptions about flu vaccines. Cedars Sinai. Bacterial gastroenteritis. Mount Sinai. Viral gastroenteritis (stomach flu). National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Treatment of viral gastroenteritis ("stomach flu"). American Academy of Family Physicians: familydoctor.org. BRAT diet: Recovering from an upset stomach. Afacan MA, Tayfur İ. Comparison of the effects of metoclopramide and ondansetron on emergency service observation times in acute gastroenteritis-related nausea and vomiting cases. Sisli Etfal Hastan Tip Bul. 2019;53(2):186-189. Published 2019 Jul 11. doi:10.14744/SEMB.2019.80217 Nemours KidsHealth. Gastroenteritis (stomach flu). University of Rochester Medical Center. Viruses, bacteria, and parasites in the digestive tract. Australian Government, Depart of Health: healthdirect. Gastroenteritis. Graves NS. Acute gastroenteritis. Prim Care. 2013;40(3):727-741. doi:10.1016/j.pop.2013.05.006 National Institutes of Health. Definition & facts for viral gastroenteritis (“stomach flu”). U.S. Department of Health and Human Services. By Kristina Duda, RN Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit