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from the desk of:
Steve Marchbank,
MD
Viral Gastroenteritis (Commonly called Stomach Flu)
What is gastroenteritis/stomach flu?
‘Stomach flu’ is a viral infection that affects the stomach and intestines (mostly the small intestine). It is also called viral
gastroenteritis. The illness may be brief, lasting 1 to 3 days; however, it may last for longer periods, up to 7-10 days.
Sometimes, these infections MAY last even longer than 10 days - although it is often difficult to tell if this is still the same
infection, a new (2nd infection) infection, or re-infection from another person - for more prolonged (>10 days) infections, it
is best to talk to or see your physician.
What causes it?
Gastroenteritis is caused by catching or swallowing certain viruses. The body fluids (feces, diarrhea, saliva) of infected
people contain the virus, sometimes even before their symptoms begin. The virus can be spread by direct contact with an
infected person (for example, kissing or shaking hands) or by sharing food, drink, or eating utensils.
The virus enters the stomach and intestine and inflames the lining of these organs. As a result, the stomach and intestine
are temporarily unable to perform their usual functions. The virus can also cause food to move more rapidly through your
gastrointestinal (GI) tract. Normal feces has a brownish color, which happens as the food is processed by the body, as
well as the normal ‘flora’ of bacteria in our intestinal tracts. When feces passes through the body faster than normal, it is
often looser and lighter or different in color. The stomach makes clear-colored secretions, while the small intestine’s
secretions are yellow or green. Therefore, diarrhea will often be yellowish or greenish in color, because the body (and its
normal bacteria) has not had time to fully process the feces.
Thus, diarrhea with gastroenteritis may be brownish, yellowish or greenish. Vomitus (emesis) is usually the color of
whatever food/drink recently eaten. However, if vomitus is yellow or green (and you haven’t recently eaten anything
yellow/green), you should contact your physician (this can indicate a problem with the movement of material thru the
intestines, a blockage, etc.)
Viruses that typically cause gastroenteritis include: Rotavirus, adenovirus, calicivirus, astrovirus, Norwalk virus/agent, and
hundreds of other virus and Norwalk-like agents. Some bacteria and other tiny organisms called protozoa can cause
infections that have symptoms similar to those of stomach flu; however, the vast majority of gastroenteritis in children is
caused by viral infections.
What are the symptoms?
When you have stomach flu, you may have one or more of the following symptoms:
 Fatigue, chills, loss of appetite, nausea, vomiting, stomach cramps, diarrhea, fever and muscle aches.
The illness may develop over a period of hours, or it may suddenly start with stomach cramps, vomiting, or diarrhea.
Gastroenteritis may follow many different courses. Often, vomiting (with or without diarrhea) will occur initially, with
diarrhea closely following. Typically, the vomiting will improve after a few days, but diarrhea may persist for several more
days. Following the acute ‘illness’ phase, loose stools may continue for days, especially if an appropriate diet is not
maintained.
How is it diagnosed?

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Your health care provider will review your symptoms. The diagnosis is usually made by a careful history, a combination of
symptoms, and occasionally laboratory tests. If symptoms are severe, lab tests may be done to rule out more serious
illnesses, such as appendicitis, and to detect complications, such as dehydration.
How is it treated?
By far the most feared complication of gastroenteritis is dehydration. Therefore, retaining fluids and maintaining hydration
is the mainstay of treatment.
First, you want to rest the stomach/intestines and to go SLOWLY. You can do this by first eating nothing (no food, cereals,
fruits, veggies, etc) and drinking fluids in small amounts.
The BEST fluids to drink are fluids that contain a balance of glucose (sugar), electrolytes (sodium, potassium, etc) and
free water. Certain combinations are better than others, as too much of one may actually be harder to absorb and digest.
Examples of preferred fluids are:
Pedialyte (flavoredorunflavored) unflavored doesnot taste very good,however!
Preferred Infalyte
fluids ORS(oral rehydrationsalts) Canbe purchasedormadeat home(seebelow)
PedialytePopsicles Pedialyte Freezer Pops, others
breastmilk
Gatorade,½strength w/water Better alternative than the other “OK” fluidslisted below
Gatorade,½ strength w/ water
“OK” fluids ½ strength juices Esp white grape& apple;wouldavoid pruneand orangejuice
Water (if not dehydrated) If not dehydrated, water is ok, but not as good as above choices
“flat” 7-UP or Sprite Shouldlet it go ‘flat’, to lose carbonation
Undilutedjuices Examples:fruit juices,Gatorade,Powerade
Fluids to Plainwater (if dehydrated) Water has no electrolytes,whicharedepleted in dehydration
avoid Milk& dairy Includinggoat’smilk
Formulascontaininglactose Examples:Enfamilw/Iron, EnfamilAR, CarnationGoodStart
Caffeinatedliquids
Acidic orcarbonatedfluids Examples:sodaor pop, orangejuice
During the vomiting phase of the illness it is best to have only small, frequent sips of liquids. Drinking too much at once,
even an ounce or two, may cause more vomiting.
Later, if tolerating liquids and not vomiting, you can add soft bland foods that are easy to digest. Examples include the
BRAT diet (B=bananas R=rice A=applesauce T=toast), crackers, etc.
You may start eating soft bland foods when you have not vomited for several hours and are able to drink clear liquids
without further upset. Examples include the BRAT diet (B=bananas R=rice A=applesauce T=toast), Soda crackers, plain
noodles are good first choices. Avoid foods that are acidic, spicy, fatty, or fibrous (meats, coarse grains, vegetables) and
dairy products. You may start eating these foods again in 3 days or so, when all signs of illness have passed. Dairy and
lactose containing fluids (milk, certain formulas, etc) should be avoided until the illness is over. If the diarrhea has been
present for several days, it is best to not resume lactose until the diarrhea and loose stools have been better for 3-5 days.
Medications for diarrhea are not routinely recommended, but occasionally vomiting will be treated with anti-emetics like
Phenergan. However, before using ANY medicines for gastroenteritis (whether prescription or non-prescription), please
consult with your own physician.

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Dehydration is a potentially serious complication of stomach flu. It can occur if your body loses too much fluid because
you keep vomiting or having diarrhea. If you are severely dehydrated, you may need to be given fluids intravenously (IV).
In infants and the elderly, dehydration can quickly become life threatening.
How long do the effects last?
Gastroenteritis usually lasts from 1 to 5 days, but the total illness may last up to 10 days, as it may be some time before
your bowel habits return completely to normal.
Call your health care provider if:
 You have severe symptoms for more than 2 or 3 days.
 Minor symptoms persist for several days (for example, loss of appetite, nausea, diarrhea).
 You develop symptoms that are not usually caused by stomach flu, such as blood in your vomit or bloody
diarrhea.
 Signs of dehydration
What are the signs of dehydration?
Dehydration in infants may include: sunken fontanelle (soft spot), not making tears with crying, less than 3-4 wet diapers
in 24 hours, dry lips/mouth, pale or mottled skin color, decreased activity/lethargy OR irritability, weight loss.
In older children, they include decreased urination, dry lips/mouth, poor skin color, no tears with crying, weight loss and
decreased activity.
What can I do to help prevent stomach flu?
The single, most helpful way to prevent the spread of stomach flu is frequent, thorough hand washing. Also, avoid contact
with the body fluids of an infected person, including saliva and feces/urine. Closed, crowded settings with babies/children,
such as day-cares, nurseries and school settings, are especially likely to spread infection.
How to make your own Homemade ORS (Oral Rehydration Solution):
In a clean container, mix the following:
One liter (or quart) of clean drinking water PLUS
Eight level teaspoons of sugar PLUS
One level teaspoon of salt

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Gastroenteritis (Stomach Flu) Overview
 Usually caused by a virus, meaning antibiotics are unfortunately not helpful
 Medications such as anti-diarrheals (Imodium) are not recommended
 Treatment is supportive, aimed at preventing dehydration, the main complication and
most common reason for hospitalization (in severe cases)
 Hydration is maintained by taking appropriate fluids (clears, as listed in included
table) in small amounts, and often. It is best to start with very small amounts (1-2
tsp) every few minutes, and increase slowly if tolerating. Example, if keeping an ounce
down every 30 minutes, may try going up on the amount slowly; however, if vomiting
returns, you should ‘back off’ and again lower the amount of clear fluids being given,
then slowly work back up again – be patient, it may be very slow going! 
 Once tolerating fluids well (without vomiting), then a bland food diet may be
introduced. However, if vomiting returns, then BACK UP to fluids only (and in small
amounts) and no more food
 It is best to maintain a rather bland diet for several days after the resolution of the
illness (including avoidance of dairy/lactose), so that the gastrointestinal tract can
fully recover
 If signs of dehydration develop, or other signs of potentially serious illness are present
(such as lethargy, excessive somnolence, intolerance of even small fluid amounts, etc)
or most importantly, you as parents are worried, contact your physician immediately