Gastroenteritis (Stomach Flu)
Acute gastroenteritis is a rapid-onset diarrheal disease that can include symptoms such as fever, nausea, vomiting and abdominal pain. Viruses, such as norovirus and adenovirus, cause the vast majority of cases. But bacteria and parasites may also contribute to this type of illness. Symptoms usually last less than two weeks.
179 million episodes.
1 in 15 Americans will suffer from viral gastroenteritis each year.
600,000 hospitalizations and 5,000 deaths per year.
Symptoms
How can you tell if you have food poisoning or a virus?
Timing of symptoms is the most important differentiating factor between foodborne and viral illnesses.
Food poisoning—or foodborne illness—can refer to a variety of different diseases, but typically describes an acute onset of nausea, vomiting, and/or diarrhea within six hours of a suspect meal. In these cases, a preformed toxin (usually by staph aureus) causes an inflammatory reaction within the gastrointestinal tract leading to symptoms.
Viral illnesses, which can also be passed through food, have a longer incubation period—typically greater than 16 hours—and are more likely to include low-grade fever.
What are the most common gastroenteritis symptoms?
Fortunately, the majority of gastroenteritis cases do not last more than a few days, and definitely no longer than two weeks. Most people will suffer from nausea, vomiting, watery diarrhea, abdominal cramping and, sometimes, a low-grade fever.
Medically, what makes you worry it could be something that needs more treatment or attention than a typical gastroenteritis?
Symptoms become more worrisome when they include persistent or high fever (> 101 F), blood in the stool, painful bowel movements, and the inability to keep hydrated. Symptoms that don’t start to show improvement after five days are also concerning.
Do people need to have an exam or tests?
Stool analysis in patients with acute gastroenteritis can help determine if an infection is bacterial. However, since viruses cause the majority of cases of gastroenteritis, most people with symptoms lasting more than days and with no warning symptoms such those as listed above do not need additional testing.
Testing can help guide treatment in patients with a specific clinical history, such as recent ingestion of raw oysters or undercooked meats, or recent antibiotic use--all of which make a bacterial cause more likely.
Are there patients who are vulnerable to getting more serious infections or becoming more ill?
Patients who have a compromised immune system or are likely to get dehydrated rapidly require greater care. These patients include young children, people who are on immunosuppressant medications or have AIDS, and the elderly. Women who are pregnant should also take special care.
Treatment
What’s the best gastroenteritis treatment?
Fortunately, the vast majority of gastroenteritis cases will get better by themselves and only require rest and proper hydration. If nausea or vomiting persist, a medical provider can prescribe an antiemetic (medication to reduce vomiting).
Antidiarrheal medication (e.g. Imodium) can be used for most viral gastroenteritis, but only when required for unavoidable travel or appointments. They can prolong the course of the illness and, though rarely, lead to more serious complications. As a result, they should be avoided entirely in patients with blood in their stool, or when there’s concern over bacterial cause for the diarrhea.
The goal for medical providers is to determine which patients would benefit from antibiotics to shorten the course their illness and which should avoid them (and any associated side effects).
What about anti-nausea medications?
Antiemetic medication ameliorates the unpleasant symptom of nausea and decreases the frequency of vomiting in patients suffering from gastroenteritis-induced vomiting.
In studies of pediatric gastroenteritis, the use of ondansetron, one type of antiemetic medication, reduced the need for intravenous rehydration and reduced hospitalizations. Ondansetron, compared to other antiemetic medication, causes fewer side effects and sedation, although it can temporarily worsen diarrhea.
Keeping this in mind, ondansetron should be used at the lowest effective dose and for the shortest amount of time. Nausea and vomiting lasting more than two days (uncommon in gastroenteritis) should be evaluated by a medical provider.
Does anything actually fight the infection?
There are no medications that specifically treat viral gastroenteritis. Antibiotics, however, can help bacterial gastroenteritis and prevent possible complications. High fevers, blood in the stool, or painful bowel movements indicate that a patient should seek further evaluation by a medical provider.
Lifestyle Approaches
What can people do alleviate their symptoms?
Dehydration plays an important role in making patients feel poorly during bouts of gastroenteritis. Proper fluid intake can help them avoid prolonged illness, as well as alleviate symptoms such as fatigue, listlessness, light-headedness, and elevated body temperature.
In most cases, broth and sports drinks are sufficient for replenishing electrolytes. In more severe instances, however, studies have found that specially-formulated oral rehydration solutions (e.g. Pedialyte) do a better job.
As appetite returns, it’s best to start with small, bland meals. That said, newer studies show that we don’t need to restrict our diet as much as previously thought. An early return to a normal foods can attenuate changes in intestinal permeability and reduce illness duration.
In the early aftermath, continue to avoid simple sugars (sodas, juices, sweets), which can increase osmolarity within the gut and worsen diarrhea. Whether or not to avoid dairy products (except yogurt) is still a matter of debate and seems like a reasonable approach, at least for the duration of the illness.
Why isn’t water the best option for rehydration?
The body loses both water and electrolytes with vomiting and diarrhea. It’s important to replenish the electrolytes as well. The WHO recommends a solution of water with salts (sodium and potassium) in addition to sugar. This is particularly important for children and others who may be more vulnerable to electrolyte abnormalities.
What are other interventions that may help alleviate symptoms?
Ginger, an ancient medicinal plant, has been shown in multiple studies to decrease nausea and vomiting in different populations, including children suffering from stomach flu symptoms.
There are, however, many preparations of ginger, some more potent than others. The studies looked at various doses and formulations, and 500 mg of high quality ginger capsules taken every eight hours showed a consistent effect.
Other equivalent preparations are ½ tsp (2.5 grams) of grated fresh ginger, two cups of ginger tea, one ml of ginger extract, or one piece of crystalized ginger taken every eight hours.
Prevention and Research
How contagious is gastroenteritis and how can people avoid infection?
Viral gastroenteritis—especially norovirus, the most common viral cause—is exceptionally contagious. The CDC recommends regular hand washing, proper food preparation, and staying at home during and two days after illness to decrease contagion.
Is there any interesting new research in this area?
The evidence for use of probiotics to prevent or to treat gastroenteritis is mixed. The variety of different probiotic preparations, species, concentrations and dosing regimens makes it difficult to study.
Still, a recent article in the Journal of Clinical Gastroenterology concluded that there was strong evidence that probiotics, in addition to rehydration, are an effective treatment for gastroenteritis. They went on to say that the evidence is strongest for Lactobacillus rhamnosus GG and Saccharomyces boulardii species.
Useful Links
General food poisoning information (CDC)
What to know about acute diarrhea in adults (American Family Physician)
Connect with our physicians
Jamila Schwartz, MD and Steven Winiarski, DO are both members of the Galileo Clinical Team. Connect with one of our physicians about Gastroenteritis (Stomach Flu) or any of the many other conditions we treat.