Why Do Kids Throw Up So Much?

Children’s bodies are more sensitive to a variety of vomit-inducing stimuli.

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A child with a stomachache sitting on a bed, clutching her stomach.

Babies and kids throw up so much that it’s almost believable that they like it. But why do kids seem to vomit more often than adults? How can it be prevented, and when is vomiting cause for serious concern?

“Anything that makes a child sick can make them vomit,” pediatric gastroenterologist Katja Kovacic, M.D., told NPR. “There are numerous, numerous causes.”

And it’s not just sickness. Children’s bodies are more sensitive to a variety of vomit-inducing stimuli. “Children may vomit in response to things that wouldn’t make an adult blink: a stubbed toe, for example, or a fever, Kovacic said.

Both adults and children throw up via the same basic mechanism. In response to stress, the fight-or-flight response primes the body by diverting resources and blood flow away from the digestive system and toward the muscles that may be needed to make a quick escape. Unable to digest, the stomach often prefers to expel its contents. The glottis shuts, the larynx rises, and the diaphragm pushes downward, creating negative pressure that opens the esophagus. The stomach expels its contents, and the birthday party, fancy dinner, or quiet afternoon, is ruined.

“You literally squeeze your stomach between your abs and diaphragm,” Bill Yates, Ph.D., a neurologist at the University of Pittsburgh, told Motherboard. Interestingly, most animals cannot vomit and are considered “non-emetic.” Dogs and cats are among the few exceptions.

The primary use for vomit is urgently removing poisons from our bodies. The area postrema is a region of the brain dedicated to poison control, and is primed to evacuate the stomach in an emergency. But the area postrema does not act alone. The vagus nerve can set off heaves if something goes too far down your throat (this is where the gag reflex comes from). The stomach’s own nervous system can also prompt you to throw up if it gets too full or detects a stomach bug. And since the body has difficulty distinguishing between physical and emotional stress, the central nervous system can trigger vomiting in response to fear, grief or disgust.

In a word, vomit is there to protect you.

Why Kids Throw Up More Than Adults

To review, adults vomit for four main reasons: poison control (the arena postrema), gagging (the vagus nerve), disease (the stomach’s nervous system), and stress (the central nervous system). When you think about it, children are more likely to activate each of these vomit pathways than adults. Kids are more prone to minor illnesses and stomach bugs. They are also notoriously bad at eating their meals slowly, which means that they gag or overeat. And the central nervous system can easily read a tantrum as “outrageous stress.”

This does not mean, however, that regular unexplained vomiting in kids should be dismissed. In extreme cases, regular vomiting can be a sign of Cyclic Vomiting Syndrome and other underlying health problems. Parents should therefore not discount constant vomiting as a hazard of childhood and ask a pediatrician if they have lingering concerns.

Otherwise, the best solution is to keep your child hydrated and lying on their side. As with the many tribulations of parenthood, this too shall pass — but not before destroying the carpet.

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