Causes of Vomiting in Infants & Children

By: Anthony Porto, MD, MPH, FAAP

Many common childhood illnesses can cause vomiting. You can expect your child to throw up several times during their early years.

An episode of vomiting usually ends quickly without treatment. But this doesn’t make it any easier for you to watch your child go through it. Understanding the causes of vomiting and what to do when it happens can help.

Vomiting vs. spitting up

First, there’s a difference between real vomiting and just spitting up. Vomiting is the forceful throwing up of stomach contents through the mouth. Spitting up (also known as gastroesophageal reflux, or GER) is the easy flow of stomach contents out of the mouth, frequently with a burp. It is most commonly seen in infants under 1 year of age.

Vomiting occurs when the abdominal muscles and diaphragm contract vigorously while the stomach is relaxed. This reflex action is triggered by the "vomiting center" in the brain after it is stimulated by any of the following:

Causes of vomiting in babies & kids

Causes of vomiting can vary by to age and may include:

Gastroesophageal reflux (GER)

During their first few months, most infants spit up small amounts of formula or breastmilk—usually within the first hour after being fed. This is called gastroesophageal reflux (GER). It is caused by the occasional movement of food from the stomach, through the tube (esophagus) leading to it, and out of the mouth.

GER tends to decrease as the baby gets older, but may persist in a mild form until 10 to 12 months of age. Thankfully, it doesn’t interfere with feeding or normal weight gain. Spitting up will occur less often when a child is kept upright after meals, burped frequently and active play (including tummy time) is limited right after meals.

Gastroesophageal Reflux Disease (GERD)

Occasionally the spitting up in the first few weeks to months after birth gets worse rather than better. That is, even though it’s not forceful, it occurs all the time. It can happen when the muscles at the lower end of the esophagus become overly relaxed, which allows stomach contents to back up. This condition is known as gastroesophageal reflux disease, or GERD.

While GER is typically normal, GERD may be associated with feeding problems. Examples including pain with feeding, respiratory symptoms such as gagging and coughing, and poor weight gain. GERD usually can be controlled with steps that include:

Hypertrophic pyloric stenosis

Occasional vomiting may occur during a baby's first month. If it appears repeatedly or is unusually forceful, call your pediatrician. It may be just a mild feeding difficulty, but it also could be a sign of something more serious known as hypertrophic pyloric stenosis.

Hypertrophic pyloric stenosis usually starts at around 2 weeks to 4 months of age. It is caused by a thickening of the muscle at the stomach exit that revents food from passing into the intestines. This condition requires immediate medical attention. Surgery usually is needed to open the narrowed area.

The important sign of hypertrophic pyloric stenosis is forceful vomiting occurring approximately 15 to 30 minutes or less after every feeding. Anytime you notice this, call your pediatrician as soon as possible.

Food protein-induced enterocolitis (FPIES)

Vomiting may also be seen with food protein induced enterocolitis (FPIES), a rare type of food allergy seen mostly in young infants. It causes episodes of severe, repeated vomiting, followed by diarrhea, starting several hours after eating the food that triggered it. Symptoms of FPIES can be confused for a GI infection (see more about these below).

FPIES usually presents when solid foods are introduced into a baby’s diet, at around 4-6 months of age. It is mostly commonly triggered by rice, wheat, oat, sweet potato or poultry, but can happen with other foods as well. FPIES can also develop earlier, in the first months of life, with exposure to milk or soy. Vomiting and diarrhea from FPIES can lead to dehydration, so intravenous (IV) fluids may be needed.

Gastrointestinal infection

Once a baby is a few months old, the most common cause of vomiting is a stomach or intestinal infection. Viruses are by far the most frequent culprit, but occasionally bacteria and even parasites may be the cause. The infection also may produce fever, diarrhea, and sometimes nausea and abdominal pain.

An intestinal infection is usually contagious; if your child has it, chances are good that some of their playmates also will be affected.

Rotavirus is one of the viral causes of gastroenteritis. Other types of viruses—such as noroviruses, enteroviruses and adenoviruses—can cause it as well.

Occasionally infections outside the gastrointestinal tract will cause vomiting. These include infections of the respiratory system, infections of the urinary tract, middle ear infections, meningitis and appendicitis.

When should I be concerned about my child vomiting?

Be alert for the following trouble signs, whatever your child’s age, and call your pediatrician immediately if they occur: