Stomach Flu

1 What is Viral Gastroenteritis (Stomach Flu)?

Viral gastroenteritis, or the stomach flu, is an infection of the intestine. It is characterized by inflammation of the lining of the stomach, large intestine, and small intestine.

Telltale signs include:

One way of getting it is through contact with contaminated water or food.

The usual cause of gastroenteritis or stomach flu is viral infections. Bacteria sometimes bring it on.

Gastroenteritis isn’t the same as influenza. Influenza affects the respiratory system, the nose, throat and lungs, whereas gastroenteritis or stomach flu attacks the intestines.

It is very possible to recover from this without any complications. However, in people with a compromised immune system, it can be deadly.

Prevention is more important than treatment. Avoid food and water which is contaminated, and wash hands frequently. This is your basic and most helpful defense. 

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2 Symptoms

The symptoms of viral gastroenteritis (stomach flu) may come after a day or two and the effect may be mild or severe. Symptoms may also take a day or two, or get persistent for more than 10 days.

Even when referred to as stomach flu, gastroenteritis is not similar to influenza. The actual flu affects your respiratory system (nose, throat, and lungs).


Gastroenteritis affects the small intestines which are associated with

Muscle aches may be felt sometimes, headache, low grade fever and this will vary with the cause of viral-gastroenteritis.

It is often confused with diarrhea caused by bacteria Clostridium difficile, salmonella and E. coli, or parasites, such as giardia.

It is recommended that you see a doctor almost immediately. The same effects can also be observed in small children. But check for signs of dehydration, by looking at how often they urinate, vomit and the nature of their stool.

When vomiting, check out for the reasons why they vomit since it is not a common condition for the children to vomit. Call your doctor right away. If the baby vomits for more than a few hours, has a wet diaper in six hours, has a bloody stool, sunken soft spot on the head, has a dry mouth and cries without tears, is sleepy, drowsy and unresponsive, there is need for medical checkup for the infant.

When people are dehydrated, their skin does not flatten back to normal right away after being pinched gently and then releasing it. This is one of the checks to see if the person is dehydrated.

3 Causes

Viral gastroenteritis is most likely caused when eating or drinking contaminated water or food. Sharing of utensils, towels, and food with an infected person may also lead to infection.

There are a number of viruses that can lead to gastroenteritis.


This is common in both children and adults and is the most common cause of foodborne infections worldwide. 

It affects both families and communities, but is most likely to occur in confined spaces. It is often transmitted through contaminated food and water. 


Rotavirus is the most common cause of the stomach flu in children. It is a result of putting their fingers and foreign contaminated objects in their mouth. This infection is very severe in infants and small children.

Symptoms may not present in adults but can still spread through contacts. A vaccine is available in developed countries and it is effective in management of infection.

Contaminated water and raw shellfish can cause the disease. The virus is transmitted through the fecal-oral route, so washing your hands is very essential in preventing infection. 


Caliciviruses affect people of all age groups. Norovirus is one of the most common caliciviruses. It is also the most common cause of viral gastroenteritis in adults.

Norovirus is responsible for epidemics of viral gastroenteritis. People infected with this virus typically complain of abdominal cramps, diarrhea, fatigue, muscle pains, vomiting, etc.

These symptoms usually appear one to two days after the person is exposed to the virus. This lasts for one to three days.


Astrovirus usually affects infants and young children. Though uncommon, adults may also become infected. The symptoms could be vomiting and watery diarrhea.

Astrovirus symptoms are usually less severe than those of norovirus or rotavirus infections. This virus is most active during the winter season, but infections can occur all year.

The symptoms of someone infected with astrovirus usually appear three to four days after exposure, and symptoms last for two to seven days.

4 Making a diagnosis

Diagnosis of viral gastroenteritis (stomach flu) will be made based on symptoms and physical examination.

Both you and your child may need to visit a doctor. In case of a positive diagnosis, you may need to be referred to an infectious disease specialist.

Before seeing your doctor, take the time to note your or your child's symptoms, and when they occur.

Here are some questions you could ask your doctor:

  • What is the likely cause of the disease?
  • Are there any other possible causes?
  • Are there tests that can be done?
  • Which is the best treatment?
  • Are there any alternatives?
  • Are there medicines for these diseases?
  • How do I manage this condition from home?

However, you also need to prepare to answer some questions from your doctor, such as:

  • When did the symptoms start?
  • Are the symptoms continuous?
  • How severe are they?
  • Does anything improve your symptoms?
  • Does anything worsen your symptoms?
  • Has anyone you know suffered the same condition recently?
  • If yes, when was that?

Your doctor will advise you to drink plenty of water to reduce dehydration, and to eat bland food to lower the effect of stress on your digestive system.

If you have the stomach flu and are breastfeeding, discuss with your doctor to make sure the baby will be safe.

A rapid stool test may also be done to find whether rotavirus or norovirus are present.

This will also help rule out bacterial or parasitic infection. 

5 How is the gastroenteritis infection transmitted?

Gastroenteritis viruses are present in stool and vomit of those who are infected. The ones who are infected may contaminate utensils, surfaces, objects, food and drinks with the virus especially if they do not wash their hands thoroughly after using bathroom each time. When such infected person with unwashed hands shakes hand or touches another person, the virus is then transmitted to the other person. This virus also can be airborne when the infected person vomits.

When to visit the doctor

For an adult, you would need to inform your doctor if:

For infants and small children, check with your doctor if:

  • Any of the above symptoms occur
  • The child seems very cranky and lethargic
  • The child is in a lot of pain, restless, and uncomfortable

Immediate emergency attention is required when:

  • An infant or child's vomiting lasts for more than several hours
  • The infant or child has not passed urine in six or more hours
  • The baby has a sunken soft spot on his or her head
  • Diarrhea is severe with blood spotting
  • The baby is left with no energy, or is drowsy and unusually sleepy
  • The baby without tears and has dryness in his or her mouth

6 Treatment

There is no specific treatment for viral gastroenteritis (stomach flu). Antibiotics are not effective against the management and control of viruses.

However, they may contribute to the development of antibiotic-resistant strains of bacteria.

Treatment may also involve self-care measures.

Ensure lots of fluid intake: Dehydration is one of the biggest dangers from the stomach flu. The body loses more fluid than it takes in. The most important thing is to keep hydrated at all times.

Water is most important, but when you are not eating, it is not enough as far as nutrition goes. It doesn’t replace the electrolytes such as salt and minerals which are important. The patient loses these electrolytes when dehydrated.

The drinks that replace this salt and minerals are called oral rehydration solutions (ORS). These ORS or electrolyte solutions are available at your local drug store. In cases of infants they can be bottle-fed too. Be sure to follow instructions exactly.

Children should be kept away from milk during this time since it can make the stomach worse. If you are nursing a baby check with your doctor with regards to breastfeeding or formula feeding in such instances.

Apart from milk, drinks that contain lot of acid such as orange juice or caffeine also negatively affect stomach problems.

Slowly introduce food back into the diet: Do not rush with feeding solids to your child. Take it slow, one step at a time. Once the patient or child can drink liquid and keep it down, you can slowly start adding food. The food should be bland.

You can try yogurt, rice, toast, bread, and bananas first. Once you feel the child is comfortable with the food, you can then introduce lean meat and cooked veggies.

Spicy, fried, fatty, or acidic food should be avoided. They make the problems worse.

Avoid immediate over-the-counter medicines: Do not give over-the-counter medicines to your child immediately. Time is the best medicine in cases of the stomach flu. In most cases, medicines may not help and at times can make matters worse.

Ibuprofen can cause more stomach problems in your child. Acetaminophen can cause liver problems. Anti-diarrhea medicines can make the infection last longer.

Most cases of gastroenteritis go away slowly on their own.

However, if the vomiting and diarrhea persist for more than a few days or if there are any signs of dehydration that persist, visit your doctor immediately.

7 Prevention

A vaccine for rotavirus-caused gastroenteritis is available in some countries such as the US. When it is given to a child in his or her first year, it has been shown to be effective in prevention of the disease.

Wash hands thoroughly and frequently, and make sure your children and family do the same.

Avoid sharing of utensils, glasses and plates. Avoid close contact with people who have the virus. Disinfect hard surfaces such as counters, faucets and doorknobs with bleach reagents.

When traveling, take caution when it comes to food and water. This will be effective only when you drink well sealed and carbonated bottled water. Avoid the use of ice cubes since they may be prepared from contaminated water. Use bottled water to brush your teeth. Avoid raw food such as fruits. Also, avoid undercooked meat and fish. 

Wash all fruits and vegetables before eating them or cooking them. Meat should be thoroughly cooked. All these measures prevent gastroenteritis caused by bacteria.

8 Lifestyle and coping

Lifestyle modifications are necessary for you and your child in order to cope with viral gastroenteritis (stomach flu).

To reduce dehydration and recover, allow your stomach to settle, and stop eating solid foods for some time.

Try eating ice chips and taking small sips of water. Ease slowly into eating, and gradually start to eat bland. Consider easy to digest foods such as crackers, toasts, gelatin, bananas, rice and chicken.

If nausea returns, stop eating. Avoid dairy products, caffeine, alcohol, nicotine, and fatty or highly seasoned foods. Allow yourself plenty of rest while drinking a lot of fluids.

Cautiously use medications such as ibuprofen (Advil, Motrin IB, others) or sparingly if at all. Do not give aspirin to children or teens because of the risk of Reye's syndrome, a rare and potentially fatal disease.

Seek the advice of a doctor before using a pain reliever or fever reducer. 

Never substitute water with fruit juices. Apple juice may make diarrhea worse. Avoid using over-the-counter anti-diarrheal medications, unless advised by your doctor.

Allow your baby's stomach to rest for 15 to 20 minutes after vomiting or a bout of diarrhea, then provide small amounts of liquid. If breastfeeding the infant, allow the baby to be bottle fed with small amounts of an oral rehydration formula.

Help your child rehydrate by providing an oral rehydration solution. Water isn’t absorbed well enough and also won’t replace the electrolytes that are lost due to dehydration and diarrhea.

Allow your child plenty of rest since dehydration leads to weakness.

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