Gastroenteritis: Diarrhea and Vomiting in Children

Gastroenteritis is an infection of the gastrointestinal system; in other words, an infection of the stomach and/or the intestines. Sometimes it is referred to as the stomach flu or as gastro. Note that stomach flu is unrelated to the flu caused by the influenza virus. The symptoms usually include diarrhea and/or vomiting, one or the other, or both at the same time. There may also be associated low-grade fever, abdominal pain, or cramps. In most cases, the illness lasts for three to six days. Often, there is a history of contact with a person who has had similar symptoms.

What causes gastroenteritis?

There are many possible causes of gastroenteritis in children, but the most common are viruses such as the Rotavirus, which tends to infect younger children. This is why most children with diarrhea get better on their own, without any specific medications or antibiotics. Some viruses cause symptoms of gastroenteritis only, while others can also cause cold symptoms. Other causes include bacterial infections as well as certain parasites like giardia or amoebas.

Norovirus/Norwalk Virus 

Another virus commonly associated with outbreaks of gastroenteritis is the Norwalk virus also known as the Norovirus. First discovered in Norwalk, Ohio, this virus has been at the root of several epidemics or outbreaks of gastroenteritis across North America in hospital emergency rooms, schools, and even on cruise ships. There is a group of similar or related viruses that are referred to as Norwalk-like viruses or agents.


The rotavirus is the most common cause of serious gastroenteritis in babies and children less than two years of age. The symptoms and complications are the same as described above. The reason I mention this virus is that there is now a vaccine for Rotavirus, given by mouth to infants less than six months of age. This vaccine has been shown to be effective in preventing this infection in young babies who are at high risk for dehydration and the need for hospitalization from gastroenteritis.

Bacterial causes of gastroenteritis

Less commonly, several different types of bacteria can also cause gastroenteritis. Importantly, food poisoning is a form of gastroenteritis that can occur if a person eats or drinks contaminated (spoiled) food or water. This is why—in order to prevent food poisoning—it is necessary to cook foods well and to make sure that they are properly refrigerated.

Treating gastroenteritis

The main concern when dealing with diarrhea (and/or vomiting) is dehydration and trying to prevent it as much as best as possible. Children, especially young babies and infants can easily become dehydrated if they lose more fluid than they take in, which can be quite dangerous. So taking care of them is like playing catch-up, with the goal being for them to drink enough fluids to make up for the fluid lost in the diarrhea and/or vomiting. Fortunately, in most cases, the treatment is simply to give the child adequate amounts of fluid, depending on the severity of the symptoms.

Recently, healthcare providers have modified their approach to treating mild cases of diarrhea and usually do not change the child’s diet at all. In moderate illness, specific liquids are used, called oral rehydration solutions. Never give only water to a child who is vomiting or has diarrhea. This can be dangerous. The body needs specific amounts of salt and sugar, which are not in adequate amounts in water nor in watered-down juices and soft drinks. Only oral rehydration solutions such as Pedialyte® and Infalyte® contain the right amounts of sugar and salt. Generally, milk can be continued as long as it does not make the diarrhea worse. Breastfeeding can usually continue as well. Also, if a child is hungry, let him eat.

If a child has just vomited, parents should wait for half an hour and then begin giving fluids starting with one tablespoon. If the child keeps that down, five minutes later, one and a half tablespoons can be given, and so on, progressively increasing the amount each time by adding another half a tablespoon every five to ten minutes. Should the child vomit again, take a break for about thirty minutes and start the cycle over again. If the child cannot keep any fluids down, medical attention should be sought. Happily, most children will be able to keep down enough fluid, and the vomiting, as well as any other associated gastroenteritis symptoms, will go away on its own. If a vomiting child also has a fever and cannot keep the fever medication down, suppository acetaminophen is a very practical solution.

Most cases of diarrhea are caused by viruses, which are not treated by antibiotics. In certain cases of bacterial infection, antibiotics may be prescribed, depending on the individual situation, the age of the child, and the specific type of bacteria causing the infection. In addition, if the cause is a parasite (very rare in North America), anti-parasitic medications are prescribed. Note that anti-diarrheal medicines should not be used in children as they are not helpful and indeed may be harmful.

Protracted diarrhea of childhood

In the past, most children with diarrhea would be fed a very bland diet for prolonged periods. This approach actually made matters worse. Modern medicine has now come to recognize a condition called Protracted Diarrhea of Childhood. Children suffering from this condition have diarrhea that simply will not go away and they needed to be admitted to the hospital for weeks or even months of intravenous therapy. They might have started off with a simple or typical viral-induced diarrhea, which just seemed to get worse. It is now understood that this protracted diarrhea is due to the fact that these children were being given low-calorie diets. Because the intestinal lining did not get enough nutrition, it became damaged and started to leak, allowing liquids into the intestine, and causing large amounts of diarrhea. This is why current recommendations stipulate that, aside from the use of appropriate oral rehydration solutions, a normal diet should resume as soon as possible. Consequently, the so-called BRAT diet of banana, rice, apple sauce, and toast, which are low in both calories and fats, should not be used for prolonged periods of time (no more than a day or two) if at all.

Signs of dehydration

In babies and young children, the signs of dehydration include

-Less frequent urination (less than six wet diapers per day, in babies);
-No tears when crying
-Dry or sticky mouth
-Weight loss
-Extreme thirst

When should a healthcare provider be consulted?

Take your child to a healthcare provider immediately if any of the following symptoms are present:

There are signs of dehydration;
Your baby is younger than three months;
There is blood in the stool;
There is frequent vomiting preventing a child from drinking;
Diarrhea lasts for more than one week;
Your child complains of abdominal pain, looks or behaves unwell, and/or has a high fever.

Severe cases of diarrhea and/or vomiting and dehydration are relatively rare. The only treatment is the administration of intravenous fluids in a hospital setting. Because each child is different, treatment is based on the individual situation.

Are special tests needed?

In most children with diarrhea, stool tests or other tests are not necessary. However, if a physician suspects bacteria as the cause, then a stool culture (a test for bacteria or parasites) will be collected and sent for laboratory testing.


The prevention approach for gastroenteritis is hand washing before and after contact with any infected individual, and decontamination of areas such as toilets, sinks, and other objects that might have come in contact with infected stool or vomit.

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Pediatrician DR.PAUL Roumeliotis is certified by the American Board of Pediatrics and Royal College of Physicians and Surgeons of Canada. The information provided above is designed to be an educational aid only. It is not intended to replace the advice and care of your child’s physician, nor is it intended to be used for medical diagnosis or treatment. If you suspect that your child has a medical condition always consult a physician.