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Nausea and Vomiting


Jonathan Gotfried

, MD, Lewis Katz School of Medicine at Temple University

Last full review/revision Mar 2020| Content last modified Mar 2020
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Topic Resources

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.


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:

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 (cannabis 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 functional 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).


Some Causes of Nausea and Vomiting


Suggestive Findings*

Diagnostic Approach

Gastrointestinal disorders

Obstipation, distention, tympany

Often bilious vomiting, abdominal surgical scars, or hernia

Flat and upright abdominal x-rays

Vomiting, diarrhea

Benign abdominal examination

Clinical evaluation

Gastroparesis or ileus

Vomiting of partially digested food a few hours after ingestion

Often in diabetics with elevated blood glucose or after abdominal surgery

Flat and upright abdominal x-rays

Sometimes gastric emptying scan

Mild to moderate nausea for many days, sometimes vomiting

Jaundice, anorexia, malaise

Sometimes slight tenderness over the liver

Serum aminotransferases, bilirubin, viral hepatitis titers

Perforated viscus or other acute abdomen (eg, appendicitis, cholecystitis, pancreatitis)

Significant abdominal pain

Usually peritoneal signs

Toxic ingestion (numerous)

Usually apparent based on history

Varies with substance

Central nervous system (CNS) disorders

Closed head injury

Apparent based on history

Head CT

CNS hemorrhage

Sudden-onset headache, mental status change

Often meningeal signs

Head CT

Lumbar puncture if CT is normal

CNS infection

Gradual-onset headache

Often meningeal signs, mental status change

Sometimes petechial rash* due to meningococcemia

Head CT

Lumbar puncture

Increased intracranial pressure (eg, caused by hematoma or tumor)

Headache, mental status change

Sometimes focal neurologic deficits

Head CT

Vertigo, nystagmus, symptoms worsened by motion

Sometimes tinnitus

Headache sometimes preceded or accompanied by a neurologic aura or photophobia

Often a history of recurrent similar attacks

In patients with known migraine, possible development of other CNS disorders

Clinical evaluation

Head CT and lumbar puncture considered if evaluation is unclear

Apparent based on history

Clinical evaluation

Psychogenic disorders (eg, anorexia and bulimia nervosa)

Occurring with stress

Eating food considered repulsive

Clinical evaluation

Systemic conditions

Advanced cancer (independent of chemotherapy or bowel obstruction)

Apparent based on history

Clinical evaluation

Polyuria, polydipsia

Often significant dehydration

With or without history of diabetes

Serum glucose, electrolytes, ketones

Drug adverse effect or toxicity

Apparent based on history

Varies with substance

Liver failure or renal failure

Often apparent based on history


Often jaundice in advanced liver disease, uremic odor in renal failure

Laboratory tests of liver and renal function

Blood ammonia level


Often occurring in morning or triggered by food

Benign examination (possibly dehydration)

Pregnancy test

Apparent based on history

Clinical evaluation

Severe pain (eg, due to a kidney stone)

Varies with cause

Clinical evaluation

* Sometimes forceful vomiting (caused by any disorder or condition) causes petechiae on the upper torso and face, which may resemble those of meningococcemia. Patients with meningococcemia are usually very ill, whereas those with petechiae caused by vomiting often appear otherwise quite well.

Etiology reference

Evaluation of Nausea and Vomiting


History of present illness should elicit frequency and duration of vomiting; its relation to possible precipitants such as 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 drugs 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 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.


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 x-rays, 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 Drugs for Vomiting). Choice of agent varies somewhat with the cause and severity of symptoms. Typical use is the following:

  • Motion sickness: Antihistamines, scopolamine patches, or both

  • Mild to moderate symptoms: Prochlorperazine or metoclopramide

  • Severe or refractory vomiting and vomiting caused by chemotherapy: 5-HT3 antagonists, neurokinin-1 receptor antagonists (eg, aprepitant)

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.


Some Drugs for Vomiting


Usual Dose


Oral antihistamines


50 mg every 4–6 hours

Used to treat vomiting of labyrinthine etiology (eg, motion sickness, labyrinthitis)


25 mg every 8 hours

5-HT3 antagonists


12.5 mg IV at onset of nausea and vomiting

Used to treat severe or refractory vomiting, or vomiting caused by chemotherapy

Possible adverse effects: Constipation, diarrhea, abdominal pain


1 mg orally or IV 3 times a day


4–8 mg orally or IV every 8 hours


Prophylaxis: 0.25 mg IV as a single dose 30 minutes before chemotherapy

Other drugs


125 mg orally 1 hour before chemotherapy on day 1, then 80 mg daily in the morning on days 2 and 3

When used with ondansetron, 32 mg IV 30 minutes before chemotherapy only on day 1

When used with dexamethasone 12 mg orally 30 minutes before chemotherapy on day 1 and 8 mg daily in the morning on days 2, 3, and 4

Used with highly emetogenic chemotherapy regimens

Possible adverse effects: Somnolence, fatigue, hiccups


5–20 mg orally or IV 3 to 4 times a day

Used to treat initial treatment of mild vomiting


5–10 mg IM or 8–16 mg orally daily in divided doses; maximum dose 24 mg/day


5–10 mg IV or 25 mg per rectum


1-mg patch worn for up to 72 hours

Used to treat motion sickness

Possible adverse effects: Diminished sweating, dry skin

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.

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