A Overview of the 24-Hour Stomach Flu

What You Should Know About Gastroenteritis

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If you have ever come down with the stomach flu and have experienced bouts of crushing nausea, vomiting, and diarrhea, it is not uncommon to be consoled by someone who will assure you that it's just a "24-hour bug."

But is there really such a thing? Can a stomach bug actually slip through your system as fast as that, leaving behind only a vague memory of the illness?

Understanding Stomach Flu

When describing a stomach bug, the word "flu" is a bit of misnomer. In purely medical terms, the flu (influenza) is a common viral infection that primarily affects the respiratory system and manifests with symptoms such as fever, chills, muscle aches, cough, and congestion.

By contrast, the stomach flu is more accurately referred to as gastroenteritis. Unlike influenza, gastroenteritis can be caused by any number of disease-causing pathogens, including bacteria, viruses, parasites, and even fungi. It is commonly associated with the rotavirus in children and either the norovirus or the Campylobacter bacteria in adults. Here's a brief look at the main differences between stomach flu and seasonal flu.

Stomach Flu
  • Also known as gastroenteritis or infectious diarrhea

  • Gastrointestinal infection that can be caused by a virus, bacterium, or parasite

  • Spreads via person-to-person contact, contaminated food or water, or, in the case of parasites, contact with infected feces

  • Symptoms include vomiting, diarrhea, fever, and stomach pain

  • Vomiting usually lasts 24 hours; diarrhea may continue for several days

  • Also known as seasonal influenza

  • Upper respiratory infection caused by a virus

  • Spreads by dissemination of virus in droplets spewed into air when an infected person sneezes or coughs; particles can travel as far as six feet

  • Symptoms include fever, chills, muscle aches, cough, and congestion

  • May last from two to 10 days

  • May be prevented with a yearly vaccine

Clearly, because the causes of stomach flu are varied, it may be overly optimistic to suggest that it will automatically resolve in 24 hours. It may do so, but it can also take up to 10 days for some to fully recover.

Stomach flu can last from 24 hours to over a week, depending on the type.


Gastroenteritis, also known as infectious diarrhea, is characterized by the inflammation of the stomach and gastrointestinal tract and can lead to vomiting, diarrhea, fever, and abdominal distress. In general stomach flu appears suddenly, hits hard, then gets better once the symptoms subside.


While many types of viral illnesses such as influenza and the common cold tend to be transmitted in the air, gastroenteritis tends to be transmitted by contaminated food and water or from person-to-person by contact. Handwashing after using the restroom and strict attention to food preparation guidelines are both aimed at preventing this transmission.

The most common causes of stomach flu include:

  • Viruses such as rotavirus, norovirus, adenovirus, and astrovirus are known to cause viral gastroenteritis. These represent around 70% of stomach flu in children (most especially the rotavirus), while the norovirus represents around 60% of all cases in the United States. The viruses are extremely contagious and easily passed from person to person or indirectly through contaminated food and water.
  • Bacterial causes include Campylobacter jejuni, Escherichia coli, Salmonella, Shigella, and Clostridium difficile. Bacteria-associated gastroenteritis is primarily related to something you ate. Of the possible bacterial causes, Campylobacter strains account for around one-third of all cases. Many of these infections are transmitted through contaminated poultry or other tainted foods, including meat, produce, and dairy products.
  • Parasites are less common causes of gastroenteritis but still account for around 3% of all cases in children. The primary culprit is Giardia lamblia which is spread through contaminated food, water or by the fecal-oral route (poor hygiene).


how to treat the stomach flu
​Illustration by Emily Roberts, Verywell

Symptoms of gastroenteritis are usually acute and resolve on their own without the need for medical intervention. The main focus of treatment is the prevention of dehydration due to the severe loss of fluids. Supportive therapies may include:

  • Rehydration with water or electrolyte-rich sports drinks (although sodas and any fruit juice high in simple sugar should be avoided)
  • A BRAT diet (consisting of banana, rice, apple, and toast) to ease a queasy stomach and help bind loose tummies
  • Anti-nausea medicines like Reglan (metoclopramide) to reduce the incidence of vomiting and lessen the risk of dehydration
  • Tylenol (acetaminophen) to relieve fever with fewer side effects and less stomach upset

When to Call a Healthcare Provider

Call your healthcare provider immediately or go to the emergency room if vomiting or diarrhea persists for more than 24 hours, if vomiting is violent (or there is blood in the vomit), if you can't keep fluids down, or if there are signs of severe dehydration (dizziness, weakness, confusion, fainting, fever over 101 F).

Frequently Asked Questions

  • How long does gastroenteritis last?

    Despite the nickname "24-hour stomach flu," most cases of gastroenteritis last longer than a day and night. Depending on the cause, a so-called stomach bug could persist for up to 10 days.

  • What happens inside your body when you have a stomach bug?

    The pathophysiology of gastroenteritis depends on the pathogen responsible for the illness. That said, in most cases, a virus, bacterium, or other microbe proliferates in either the small or large intestine, producing toxins that cause vomiting, diarrhea, inflammation, and other symptoms.

  • What is the most common cause of gastroenteritis?

    Norovirus causes the majority of acute cases of gastroenteritis in the United States. Around 80% of norovirus infections occur between November and April. Babies between 6 months and 18 months of age are especially susceptible.

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