Nausea, the unpleasant feeling of needing to vomit, represents awareness of afferent stimuli (including increased parasympathetic tone) to the medullary vomiting center. Vomiting is the forceful expulsion of gastric contents caused by involuntary contraction of the abdominal musculature when the gastric fundus and lower esophageal sphincter are relaxed.
Vomiting should be distinguished from regurgitation, the spitting up of gastric contents without associated nausea or forceful abdominal muscular contractions. Patients with achalasia or rumination syndrome or a Zenker diverticulum may regurgitate undigested food without nausea.
Nausea and vomiting in infants and children is discussed elsewhere.
Complications
Severe vomiting can lead to symptomatic dehydration and electrolyte abnormalities (typically a metabolic alkalosis with hypokalemia) or rarely to an esophageal tear, either partial (Mallory-Weiss) or complete (Boerhaave syndrome).
If a patient is unconscious or only partly conscious, the vomitus may be inhaled (aspirated). The acid in the vomitus can severely irritate the lungs, causing aspiration pneumonia.
Chronic vomiting can result in undernutrition, weight loss, and metabolic abnormalities.
Etiology of Nausea and Vomiting
Nausea and vomiting occur in response to conditions that affect the vomiting center. Causes may originate in the gastrointestinal (GI) tract or central nervous system (CNS) or may result from a number of systemic conditions (see table Some Causes of Nausea and Vomiting).
The most common causes of nausea and vomiting are the following:
Medications or illicit drugs
Toxins
Uncommon causes of nausea and vomiting include the following:
Cyclic vomiting syndrome
Chronic nausea and vomiting syndrome
Cyclic vomiting syndrome (CVS) is an uncommon disorder characterized by severe, discrete attacks of vomiting or sometimes only nausea that occur at varying intervals, with normal health between episodes and no demonstrable structural abnormalities. It is most common in childhood (mean age of onset 5 years) and tends to remit with adulthood. Cyclic vomiting in adults can occur with chronic marijuana (cannabis) use (cannabinoid hyperemesis syndrome); the vomiting can be relieved by a hot bath and resolves after cessation of marijuana use.
Chronic nausea and vomiting syndrome is a centrally mediated syndrome or disorder of the gut-brain axis disorder characterized by the occurrence of symptoms for at least 6 months including the last 3 months. Bothersome nausea and/or vomiting occur at least once a week. This disorder should be considered in patients who, after routine investigation (including upper endoscopy), have no evidence of organic, systemic, or metabolic disease that is likely to explain the symptoms and in who self-induced vomiting, eating disorders, regurgitation, and rumination have been excluded (1).
Etiology reference
1. Stanghellini V, Chan FK, Hasler WL, et al: Gastroduodenal disorders. Gastroenterology 150(6):1380–1392, 2016. doi: 10.1053/j.gastro.2016.02.011
Evaluation of Nausea and Vomiting
History
History of present illness should elicit frequency and duration of vomiting; its relation to possible precipitants such as medication, illicit drug, or toxin ingestion, head injury, and motion (eg, car, plane, boat, amusement rides); and whether vomitus contained bile (bitter, yellow-green) or blood (red or “coffee ground” material). Important associated symptoms include presence of abdominal pain and diarrhea, the last passage of stool and flatus, and presence of headache, vertigo, or both.
Review of systems seeks symptoms of causative disorders such as amenorrhea and breast swelling (pregnancy), polyuria and polydipsia (diabetes), and hematuria and flank pain (kidney stones).
Past medical history should ascertain known causes such as pregnancy, diabetes, migraine, hepatic or renal disease, cancer (including timing of any chemotherapy or radiation therapy), and previous abdominal surgery (which may cause bowel obstruction due to adhesions). All medications and substances ingested recently should be ascertained; certain substances may not manifest toxicity until several days after ingestion (eg, acetaminophen, some mushrooms).
Family history of recurrent vomiting should be noted.
Physical examination
Vital signs should particularly note presence of fever and signs of hypovolemia (eg, tachycardia, hypotension, or both).
General examination should seek presence of jaundice and rash.
On abdominal examination, the clinician should look for distention and surgical scars; listen for presence and quality of bowel sounds (eg, normal, high-pitched); percuss for tympany; and palpate for tenderness, peritoneal findings (eg, guarding, rigidity, rebound), and any masses, organomegaly, or hernias. Rectal examination and (in women) pelvic examination to locate tenderness, masses, and blood are essential.
Neurologic examination should particularly note mental status, nystagmus, meningismus (eg, stiff neck, Kernig sign or Brudzinski sign), and ocular signs of increased intracranial pressure (eg, papilledema, absence of venous pulsations, 3rd cranial nerve palsy) or subarachnoid hemorrhage (retinal hemorrhage).
Red flags
The following findings are of particular concern:
Signs of hypovolemia
Headache, stiff neck, or mental status change
Peritoneal signs
Distended, tympanitic abdomen
Interpretation of findings
Many findings are suggestive of a cause or group of causes (see table Some Causes of Nausea and Vomiting).
Vomiting occurring shortly after medication, illicit drug, or toxin ingestion or exposure to motion in a patient with an unremarkable neurologic and abdominal examination can confidently be ascribed to those causes, as may vomiting in a woman with a known pregnancy and a benign examination. Acute vomiting accompanied by diarrhea in an otherwise healthy patient with a benign examination is highly likely to be infectious gastroenteritis; further assessment may be deferred.
Vomiting that occurs at the thought of food or that is not temporally related to eating suggests a psychogenic cause, as does personal or family history of functional nausea and vomiting. Patients should be questioned about the relationship between vomiting and stressful events because they may not recognize the association or even admit to feeling distress at those times.
Testing
All females of childbearing age should have a urine pregnancy test.
Patients with severe vomiting, vomiting lasting over 1 day, or signs of dehydration on examination should have other laboratory tests (eg, electrolytes, blood urea nitrogen, creatinine, glucose, urinalysis, sometimes liver tests). Patients with red flag findings should have testing appropriate to the symptoms (see table Some Causes of Nausea and Vomiting).
The assessment of chronic vomiting usually includes the previously listed laboratory tests plus upper GI endoscopy, small-bowel radiographs, and tests to assess gastric emptying and antral-duodenal motility.
Treatment of Nausea and Vomiting
Specific conditions, including dehydration, are treated. Even without significant dehydration, IV fluid therapy (0.9% saline 1 L, or 20 mL/kg in children) often leads to reduction of symptoms. In adults, various antiemetics are effective (see table Some Medications for Vomiting). Choice of agent varies somewhat with the cause and severity of symptoms. Typical use is the following:
Only parenteral or sublingual agents should be used in actively vomiting patients.
For psychogenic vomiting, reassurance indicates awareness of the patient’s discomfort and a desire to work toward relief of symptoms, regardless of cause. Comments such as “nothing is wrong” or “the problem is emotional” should be avoided. Brief symptomatic treatment with antiemetics can be tried. If long-term management is necessary, supportive, regular office visits may help resolve the underlying problem.
Key Points
Many episodes of nausea and vomiting have an obvious cause and benign examination and require only symptomatic treatment.
Be alert for signs of an acute abdomen or significant intracranial disorder.
Always consider pregnancy in females of childbearing age.
