Stomach Flu (Viral Gastroenteritis)




Yesterday, you were enjoying a plate of raw oysters at your favorite restaurant, and now you’re doubled over with cramps. These symptoms could be those of viral gastroenteritis — an intestinal infection marked by watery diarrhea, abdominal cramps, nausea or vomiting and sometimes fever. Often called the stomach flu, gastroenteritis is one of the most common acute illnesses worldwide, yet it has no effective treatment. Your best defense against this illness is prevention.

You usually develop gastroenteritis because you’ve been in contact with someone who’s already infected or because you’ve ingested contaminated food or water. If you’re otherwise healthy, you’re likely to recover without any complications, although you may feel miserable for a week or more. But for infants, older adults and people with compromised immune systems, gastroenteritis can be deadly.

There’s no effective treatment for gastroenteritis, so prevention is key. In addition to avoiding food and water that may be contaminated, thorough and frequent hand washing is your best defense.

Signs and symptoms

Although it’s commonly called stomach flu, gastroenteritis isn’t the same as influenza. Real flu (influenza) affects your respiratory system — your nose, throat and lungs. Gastroenteritis, on the other hand, attacks your intestines, causing signs and symptoms such as:

  • Watery, usually non bloody diarrhea. Bloody diarrhea usually means you have a different, more severe infection.
  • Abdominal cramps and pain.
  • Nausea, vomiting or both.
  • Occasional muscle aches or headache.
  • Low-grade fever.

Depending on the cause, signs and symptoms may appear within one to three days after you’re infected and can range from mild to severe. Symptoms usually last just a day or two, but occasionally they may persist as long as 10 days.

Because the symptoms are similar, it’s easy to confuse viral diarrhea with diarrhea caused by bacteria such as salmonella and Escherichia coli (E. coli) or parasites such as giardia.


You’re most likely to contract viral gastroenteritis when you eat or drink contaminated food or water, or share utensils, towels or food with someone who’s infected.

Some shellfish, especially raw or undercooked oysters, can make you sick. Contaminated drinking water also can cause viral diarrhea. But in many cases, the virus is passed through the fecal-oral route — that is, someone with the virus handles food you eat without washing his or her hands after using the bathroom.

A number of viruses can cause gastroenteritis, including:

  • Rotavirus. This is the most common cause of infectious diarrhea in infants and children worldwide — it’s also a leading cause of death among children. Every year, thousands of children are hospitalized with complications of the infection. Your child is likely to have rotavirus at least once before age 3. Children are usually infected when they put their fingers or other objects contaminated with the virus into their mouths. Even tiny amounts of rotavirus may cause a serious illness.

People with rotavirus infection are generally contagious for about 10 days after symptoms appear but may remain contagious after symptoms disappear. Adults who are infected with rotavirus usually don’t develop symptoms, but can still spread the illness. Some individuals, particularly those in institutional settings, may spread the virus but not have any symptoms of illness.

A vaccine against rotaviral gastroenteritis is available in some countries, including the United States, and appears to be effective in preventing severe symptoms. Talk to your doctor about whether to immunize your child.

  • Noroviruses. There are many different strains of noroviruses, including Norwalk virus, that all cause similar symptoms. Children and adults are most likely to be affected. Noroviruses are responsible for more than 90 percent of viral gastroenteritis outbreaks in the United States each year. Norovirus infection can sweep through families and communities, leaving everyone it infects seriously ill. It’s especially likely to spread among people in confined spaces. In addition to diarrhea, nausea and vomiting, you may experience muscle aches, headache, fatigue and low-grade fever. In most cases you pick up the virus from contaminated food or water, although person-to-person transmission also is possible. After exposure to the virus, you’re likely to feel sick within 18 to 72 hours. Most people feel better in a day or two, but you’re still contagious for at least three days — and up to three weeks — after you’ve recovered.


The best way to prevent the spread of intestinal infections is to follow these common-sense precautions:

  • Wash your hands and your children’s hands thoroughly. If your children are older, teach them to wash their hands, especially after using the bathroom. It’s best to use warm water and soap and to rub hands vigorously for at least 10 seconds, remembering to wash around cuticles, beneath fingernails and in the creases of the hands. Then rinse thoroughly. Carry towelettes for times when soap and water aren’t available.
  • Use separate personal items around your home. Avoid sharing eating utensils, glasses and plates. Use separate towels in the bathroom.
  • Keep your distance. Avoid close contact with anyone who has the virus, if possible.


Unfortunately, there’s often no specific medical treatment for gastroenteritis. Antibiotics aren’t effective against most viruses, and overusing them can contribute to the development of antibiotic-resistant strains of bacteria. To help keep yourself more comfortable and prevent dehydration while you recover, try the following:

  • Let your stomach settle. Stop eating and drinking for a few hours.
  • Try sucking on ice chips or taking small sips of water. You might also try drinking clear soda such as 7UP or Sprite, clear broths, or noncaffeinated sports drinks such as Gatorade. Affected adults should try to drink at least eight to 16 glasses of liquid every day, taking small, frequent sips.
  • Ease back into eating. Gradually begin to eat bland, easy-to-digest foods such as soda crackers, toast, gelatin, bananas, rice and chicken. Stop eating if your nausea returns.
  • Avoid certain foods and substances until you’re feeling better. These include dairy products, caffeine, alcohol, nicotine, and fatty or highly seasoned foods.
  • Get plenty of rest. The illness and dehydration may have made you weak and tired.
  • Use medications such as ibuprofen (Advil, Motrin, others) sparingly, if at all. They can make your stomach more upset. Use acetaminophen (Tylenol, others) cautiously. It sometimes can cause liver toxicity, especially in children.

(Source:  Mayo Clinic)

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