Nausea is an unpleasant feeling of needing to vomit. People also may feel dizziness, vague discomfort in the abdomen, and an unwillingness to eat.
Vomiting is a forceful contraction of the stomach that propels its contents up the esophagus and out the mouth. (See also Vomiting in Infants and Children.) Vomiting empties the stomach and often makes people with nausea feel considerably better, at least temporarily. Vomiting is quite uncomfortable and can be violent. Severe vomiting can project stomach contents many feet (projectile vomiting). Vomiting is not the same as regurgitation, which is the spitting up of stomach contents without forceful abdominal contractions or nausea. For instance, people with achalasia or Zenker diverticulum may regurgitate undigested food without nausea.
Vomitus—the material that is vomited up—usually reflects what was recently eaten. Sometimes it contains chunks of food. When blood is vomited, the vomitus is usually red (hematemesis), but if the blood has been partly digested, the vomitus looks like coffee grounds. When bile is present, the vomitus is bitter and yellow-green.
Complications
In addition to being uncomfortable, vomiting can cause complications:
Inhaled vomitus (aspiration)
Torn esophagus (Mallory-Weiss tear, Boerhaave syndrome)
Dehydration and electrolyte abnormalities
Undernutrition and weight loss
People who are unconscious or only partly conscious can inhale their vomitus. The acid in the vomitus can severely irritate the lungs.
Vomiting greatly increases pressure within the esophagus, and severe vomiting can tear the lining of the esophagus (see Injury to the Esophagus). A small tear causes pain and sometimes bleeding, but a large tear can be fatal.
Because people lose water and minerals (electrolytes) in vomitus, severe vomiting can cause dehydration and electrolyte abnormalities. Newborns and infants are particularly susceptible to these complications.
Chronic vomiting can cause undernutrition, weight loss, and metabolic abnormalities.
Causes of Nausea and Vomiting
Nausea and vomiting result when the vomiting center in the brain is activated. Causes typically involve disorders of the digestive tract or the brain, or ingested substances.
Common causes
The most common causes of nausea and vomiting are
Gastroenteritis (infection of the digestive tract)
Drugs
Toxins
Nausea and vomiting commonly occur with any dysfunction of the digestive tract but are particularly common with gastroenteritis. A less common digestive tract disorder is obstruction of the intestine, which causes vomiting because food and fluids back up into the stomach because of the obstruction. Many other abdominal disorders that cause vomiting also cause significant abdominal pain. In such disorders (for example, appendicitis or pancreatitis), it is typically the pain rather than the vomiting that causes people to seek medical care.
Less common causes
Less common causes of nausea and vomiting include
Brain or central nervous system disorders
Motion sickness
Metabolic changes or bodywide (systemic) illness
Psychologic disorders
Cyclic vomiting syndrome
The vomiting center also can be activated by certain brain or central nervous system disorders, including infections (such as meningitis and encephalitis), migraines, and disorders that increase pressure inside the skull (intracranial pressure). Disorders that increase intracranial pressure include brain tumors, brain hemorrhage, and severe head injuries.
The balance organs of the inner ear (vestibular apparatus) are connected to the vomiting center. This connection is why some people become nauseated by the movement of a boat, car, or airplane and by certain disorders of the inner ear (such as labyrinthitis and positional vertigo).
Nausea and vomiting may also occur when there are metabolic changes in the body, such as during early pregnancy, or when people have diabetes that is severely out of control or severe liver failure or kidney failure.
Chronic nausea and vomiting syndrome is a functional disorder. That is, the nausea and vomiting are not caused by a physical or specific psychologic disorder but rather may be a problem with the way the brain and gastrointestinal system communicate. In this syndrome, people have bothersome nausea, vomiting, or both that occur at least once a week for at least 6 months including the last 3 months and that have no identifiable cause after testing has been done.
Psychologic problems also can cause nausea and vomiting. Such vomiting may be intentional. For instance, people who have bulimia make themselves vomit to lose weight. Or it may be unintentional. For instance, children who are afraid of going to school vomit as a response to their psychologic distress.
Cyclic vomiting syndrome is an uncommon disorder in which people have severe attacks of vomiting (or sometimes only nausea) at varying intervals. People feel normal between attacks. Although it usually starts in childhood, it sometimes lasts until adulthood. Cyclic vomiting that begins in adulthood is often due to chronic marijuana use. The vomiting can be relieved by a hot bath and goes away after people stop using marijuana.
Evaluation of Nausea and Vomiting
Not every episode of nausea and vomiting requires immediate evaluation by a doctor. The following information can help people decide whether a doctor’s evaluation is needed and help them know what to expect during the evaluation.
Warning signs
Certain symptoms and characteristics are cause for concern. They include
Signs of dehydration (such as thirst, dry mouth, little or no urine output, and feeling weak and tired)
Headache, stiff neck, confusion, or decreased alertness
Constant abdominal pain
Tenderness when the abdomen is touched
Distended (swollen) abdomen
When to see a doctor
People who have warning signs should see a doctor right away, as should people who vomited any blood or who recently had a head injury.
People who have nausea and vomiting but no warning signs should see a doctor if vomiting continues for more than 24 to 48 hours or if they are unable to tolerate more than a few sips of liquid. People who have a few episodes of vomiting (with or without diarrhea) but are able to tolerate at least some liquids should call their doctor. Depending on their age, other symptoms, and known medical conditions (such as cancer or diabetes), the doctor may suggest that people be seen for an evaluation or stay home and try simple remedies.
What the doctor does
Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the vomiting and the tests that may need to be done ( see Table: Some Causes and Features of Nausea and Vomiting).
During the physical examination, doctors look for the following:
Signs of dehydration (such as a rapid heart rate, low blood pressure, and dry mouth)
Signs of a serious abdominal disorder (such as a distended abdomen and/or severe tenderness to the touch)
Decreased alertness or any other neurologic abnormalities suggesting a brain disorder
Doctors note any previous abdominal surgery because fibrous bands of scar tissue (adhesions) may have formed and caused an intestinal obstruction.
Although people with previously known disorders that cause vomiting (such as migraine) may simply be having a recurrence of that disorder, doctors thoroughly look for signs of a new, different problem.
Testing
The need for tests depends on what doctors find during the history and physical examination, particularly whether warning signs are present and whether findings suggest a particular disorder ( see Table: Some Causes and Features of Nausea and Vomiting).
Possible tests include
Pregnancy test
Blood and urine tests
Girls and women of childbearing age typically should have a pregnancy test.
Otherwise healthy adults and older children who have only a few episodes of vomiting (with or without diarrhea) and no other symptoms typically do not require any testing.
People whose vomiting is severe or has lasted more than 1 day or who have signs of dehydration need laboratory tests of blood (particularly electrolyte levels and sometimes liver tests) and urine.
Treatment of Nausea and Vomiting
Specific conditions are treated. If there is no serious underlying disorder and the person is not dehydrated, small amounts of clear liquids may be given 30 minutes or so after the last bout of vomiting. Typically an ounce (30 milliliters) or two are given at first. Plain water is an appropriate liquid, but broth or weak, sweetened tea may be given. Sports drinks have no particular advantage but are not harmful. If these liquids are tolerated, the amounts are increased gradually. When these increases are tolerated, the person may resume eating normal foods. Carbonated beverages and alcohol should be avoided.
Even when people are slightly dehydrated, doctors usually recommend oral rehydration solutions as long as people can tolerate some liquids by mouth. People with significant dehydration or electrolyte abnormalities, people who are actively vomiting, and people who cannot tolerate any liquids by mouth usually require fluids and/or drugs given by vein (intravenously).
For some adults and adolescents, doctors give drugs to relieve nausea (antiemetics) depending on the cause and the severity of the vomiting:
Key Points
People whose nausea and vomiting have an obvious cause and who have a normal examination only need treatment of their symptoms.
People with significant dehydration or electrolyte abnormalities usually require intravenous fluids.
Doctors look for signs of severe, sudden changes to the abdomen or disorders within the skull.
Girls and women of childbearing age are tested for pregnancy.
