Hiccups are caused by reflex spasms, or contractions, of the diaphragm -- the dome-shaped muscle separating the lungs from the stomach and other abdominal contents. As the diaphragm contracts, air is sucked into the lungs. Almost immediately afterwards, the vocal cords close, producing the typical hiccup sound.
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Hiccups begin before birth and occur frequently in newborn babies. With age, hiccups become less common. Although they can be annoying, hiccups are generally not a cause for concern. But if hiccups are very frequent, they may interfere with sleeping or other activities. Occasionally hiccups are due to a serious medical disorder.
Normal newborns spend up to 3 percent of their time hiccuping, according to “The 5-Minute Pediatric Consult.” These hiccups are not harmful and do not seem to disturb the baby. Hiccups become less and less frequent as a child gets older. Hiccups typically occur as distinct episodes lasting a few minutes to a few hours. Occasionally episodes last for days or even weeks. When an episode lasts more than a few hours or when episodes occur very frequently, they may interfere with sleeping, eating, school work or other activities.
Hiccups are often caused by an overstretched stomach, as may occur with eating or drinking too much. The stomach can also expand when a baby or older child gulps in air when drinking or eating. Frequently burping a baby during feedings may help remove the air and prevent or stop hiccups. In older children, gas bubbles in carbonated beverages can accumulate in the stomach, causing it to expand. Drinking hot or cold beverages may also precipitate hiccups by stimulating nerves in the throat, stomach or the tube connecting them, called the esophagus.
Less Common Causes
Gastroesophageal reflux disease (GERD) -- when fluids in the stomach back up into the esophagus -- is a possible cause of hiccups. In babies, frequent spitting up or vomiting during feedings suggests that GERD may be present. Older children may complain of pain in the stomach or chest. Sometimes hiccups are caused by excitement or emotional stress. If your child has recently experienced a major life change, such as entering a new school, this may precipitate frequent hiccups. Other less common causes include laughing when the stomach is empty or extreme tiredness.
Serious Medical Disorders
Occasionally hiccups are a symptom of an underlying serious health problem. This is most likely when hiccup episodes are very frequent, last for days or occur while sleeping. Many serious disorders affecting the throat, esophagus, stomach, lungs or brain may cause hiccups. This is because the reflex causing hiccups can be triggered by nerves in all of these locations. Fortunately most serious disorders in these areas are uncommon in children. Furthermore, all of these conditions cause a variety of symptoms, and it would be rare for hiccups to be the only sign of these disorders.
Seeking Medical Attention
Contact your child's doctor if hiccups are very frequent, persist for more than about 24 hours or interfere with your child's activities. Also seek medical attention if your child is failing to gain weight, has symptoms of GERD or has any symptoms of a possible underlying medical disorder of the throat, esophagus, stomach, lungs or brain.
Reviewed and revised by Mary D. Daley, MD.