Stomach Flu

What is stomach flu (viral gastroenteritis)?

Stomach flu is a viral infection that affects the stomach and small intestine. The illness is usually brief, lasting 1 to 3 days. Stomach flu is caused by a different virus than the Influenza viruses which affect the respiratory tract (nose, throat, and lungs). Learn about respiratory tract flu here.

How is it transmitted?

Stomach flu is caused by swallowing certain viruses. Infected people can spread the virus through their secretions, 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. Some bacteria and other tiny organisms called protozoa can cause infections that have symptoms similar to those of viral gastroenteritis.

Can it be prevented?

To lower the chance of getting or spreading the infection, you can:

  • Practice proper hand hygiene. Wash your hands carefully with soap and water, especially after using the toilet and always before eating or preparing food. Alcohol-based hand sanitizers may be somewhat helpful in addition to hand washing, but they are not a substitute for washing thoroughly with soap and water.
  • Avoid preparing food while infected. People who are infected with the virus should not prepare food for others while they have symptoms and for 3 days after they recover from their illness.
  • Clean and disinfect contaminated surfaces. After an episode of illness, such as vomiting or diarrhea, immediately clean and disinfect contaminated surfaces by using a bleach-based household cleaner as directed on the product label or a solution made by adding 5–25 tablespoons of household bleach to 1 gallon of water.
  • Wash laundry thoroughly. Immediately remove and wash clothing or linens that may be contaminated with vomit or fecal matter. Handle soiled items carefully—without agitating them—to avoid spreading virus. They should be laundered with detergent at the maximum available cycle length and then machine dried.
  • Wash your hands with soap and water after you use the bathroom and before you eat and avoid direct (it is not spread through the air) contact with a sick person
  • Avoid sharing eating utensils or towels and face cloths with others.

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 (liquid stools)
  • Low-grade fever
  • Muscle aches

The illness may develop over a period of hours, or it may suddenly start with stomach cramps, vomiting, or diarrhea.

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How is it diagnosed?

Your medical provider will review your symptoms. She may examine you and order lab tests to rule out more serious illnesses, such as appendicitis, and to detect complications, such as dehydration. If you have been in a foreign country or environment with poor water or sanitation conditions, tests for parasites or other infections may be done.

How long does the stomach flu last?

Stomach flu rarely lasts longer than 1 to 3 days. However, it may be 1 to 2 weeks before your bowel habits return completely to normal. Contact your medical provider (Brown students can call Health Services at 401.863-3953) if:

  • You have been vomiting for more than a day
  • You have had diarrhea for over 3 days
  • You have bloody stool
  • You have a fever over 101 F (38.3 C)
  • You feel very light-headed

How is it treated?

The most important thing to do is to rest the stomach and intestines. You can do this by first eating nothing and drinking only clear liquids. A little later you can eat soft bland foods that are easy to digest. Give your stomach rest from liquids for 2 hours after vomiting. You may suck on hard candy, a Popsicle or ice chips after 2 hours. Then take small, frequent sips of liquids every 10 to 15 minutes. 

Drinking too much at once, even an ounce or two, may cause more vomiting. Your choice of liquids is important. If water is the only liquid you can drink without vomiting, that is okay. However, if you have been vomiting frequently for a long time, you must replace the minerals, sodium and potassium, that are lost when you vomit. Ask your medical provider what sport drinks or medical products could help you replace these minerals. Other clear liquids you can drink are weak tea, bouillon and apple juice. You may also drink soft drinks without caffeine (such as 7up) after letting them lose some of their carbonation - go flat. Chilling the liquids may help you keep them down. Avoid liquids that are acidic (such as orange juice) or caffeinated (such as coffee) or have a lot of carbonation. Do not drink milk until you no longer have diarrhea. 

Avoid ibuprofen and aspirin as these may make your symptoms worse if taken on an empty stomach. If you have fever, take 2 regular strength (325 mg each) acetaminophen (Tylenol) every 4 hours. 

You may start eating bland foods when you have not vomited for several hours and are able to drink clear liquids without further upset. Soda crackers, toast, noodles, applesauce, and bananas are good first choices. Avoid foods that are acidic, spicy, fatty, or fibrous (meats, coarse grains, vegetables) and dairy products. See below for a recommended diet progression. 

Sometimes treatment includes prescription medicine to prevent nausea and vomiting or diarrhea. Nonprescription medicine, such as floperamide (Imodium) or bismuth subsalicylate (Pepto-Bismol), is available for the treatment of diarrhea and can be very effective. If you use it, make sure you use the dose recommended on the package. Pepto-Bismol can turn tongue and stools black - a harmless and transient side effect.  Imodium will not cure the diarrhea. It acts as a chemical cork while the diarrheal process (water loss from the body into the intestine) goes on. It is useful primarily if there is a period of time when it is necessary to avoid using the toilet.

Dehydration is a potentially serious complication of stomach flu (viral gastroenteritis). 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).

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Gastroenteritis Diet

Foods to avoid entirely until you are feeling better:

  • No spicy or fried foods
  • No alcohol
  • No caffeinated beverages because they dehydrate your body
  • No dried peas or beans
  • No raw or dried vegetables or fruits (except bananas)
  • No whole grain breads, cereals, or bran
  • No milk or milk products (cheese, yogurt, ice cream, or creamed soups)
  • No nuts, seeds, coconut, popcorn

Suggested progression of a diet as you recover:

Step 1:

  • Jello
  • Clear soups or bouillon
  • Decaffeinated soda (add a little sugar to “de-fizz” it)
  • Diluted apple or cranberry juice (not orange juice)
  • Gatorade or Kool-Aid
  • Water/ice chips
  • Popsicles
  • Hard candy
  • Plain saltines
  • Decaffeinated tea with honey/sweetener

Step 2:
Anything from Step 1 plus:

  • Applesauce
  • Bananas
  • Mashed potatoes
  • Plain pasta, rice - without butter, margarine or sauce
  • Refined cereals, such as Rice Crispies, puffed wheat, puffed rice, corn flakes, Cream of Wheat, Farina, Cream of Rice
  • Toast (white or light rye bread) with jelly (not jam, butter or margarine)

Step 3:
Anything from Steps 1 or 2 plus:

  • Broiled or boiled lean meat, white poultry or fish
  • Poached or boiled eggs
  • Well-cooked vegetables and fruits without seeds or skins
  • Sherbet or sorbet

When food from one step is tolerated, go to the next step. Progression through the steps may be rapid from one meal to the next as you feel better. Most people are back to a normal diet in 2 to 3 days’ time. If you find that any particular food aggravates your system or makes your condition worse, eliminate this food. In general, avoid dairy products, spicy foods and red meat until other foods are well tolerated for several days.

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How do I take care of myself?

Rest your stomach and intestines by following the guidelines, but make sure you prevent dehydration by drinking enough liquids. Drink just small amounts frequently during the vomiting phase of your illness.

What can I do to prevent it?

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 (shared cups, utensils, etc.).

Can I make an appointment at Health Services?

If you are a Brown student and you are concerned about stomach flu, you can make a confidential appointment at Health Services by calling 401.863-3953.  Health Services provides a range of services including general health care and emergency medical care. You can request a medical provider by gender or by name. We are located at 13 Brown Street on the corner of Brown and Charlesfield Streets.

Links you can use

Centers for Disease Control 

MEDLINE Plus
This site has several articles on stomach flu, including the latest news, general overviews and diagrams.

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Disclaimer: BWell Health Promiotion is part of Health Services at Brown University. Health Promotion maintains this site as a resource for Brown students. This site is not intended to replace consultation with your medical providers. No site can replace real conversation. Health Promotion offers no endorsement of and assumes no liability for the currency, accuracy, or availability of the information on the sites we link to or the care provided by the resources listed. Health Services staff are available to treat and give medical advice to Brown University students only. If you are not a Brown student, but are in need of medical assistance please call your own health care provider or in case of an emergency, dial 911. Please contact us if you have comments, questions or suggestions.