Physical exam
It is important to watch out for signs of dehydration, such as orthostatic hypotension and loss of skin turgor. Auscultation of the abdomen can produce several clues to the cause of nausea and vomiting. A high-pitched tinkling sound indicates possible bowel obstruction, while a splashing "succussion" sound is more indicative of gastric outlet obstruction. Eliciting pain on the abdominal exam when pressing on the patient may indicate an inflammatory process. Signs such as papilledema, visual field losses, or focal neurological deficits are red flag signs for elevated intracranial pressure. Diagnostic testing
When a history and physical exam are not enough to determine the cause of nausea and vomiting, certain diagnostic tests may prove useful. A chemistry panel would be useful for electrolyte and metabolic abnormalities. Liver function tests and lipase would identify pancreaticobiliary diseases. Abdominal X-rays showing air-fluid levels indicate bowel obstruction, while an X-ray showing air-filled bowel loops are more indicative of ileus. More advanced imaging and procedures may be necessary, such as a CT scan, upper endoscopy, colonoscopy, barium enema, or MRI. Abnormal GI motility can be assessed using specific tests like gastric scintigraphy, wireless motility capsules, and small-intestinal manometry. Treatment
If dehydration is present due to loss of fluids from severe vomiting, rehydration with oral electrolyte solutions is preferred. If this is not effective or possible, intravenous rehydration may be required.
Psychiatric
Nausea may be caused by depression, anxiety disorders and eating disorders. Potentially serious
While most causes of nausea are not serious, some serious conditions are associated with nausea. These include pancreatitis, small bowel obstruction, appendicitis, cholecystitis, hepatitis, Addisonian crisis, diabetic ketoacidosis, increased intracranial pressure, spontaneous intracranial hypotension, brain tumors, meningitis, heart attack, rabies carbon monoxide poisoning  and many others. Comprehensive list
Inside the abdomen
Obstructing disorders

Gastric outlet obstruction
Small bowel obstruction
Colonic obstruction
Superior mesenteric artery syndromeEnteric infections

Viral infection
Bacterial infectionInflammatory diseases

Celiac disease
Cholecystitis
Pancreatitis
Appendicitis
HepatitisSensorimotor dysfunction

Gastroparesis
Intestinal pseudo-obstruction
Gastroesophageal reflux disease
Irritable bowel syndrome
Cyclic vomiting syndromeOther

Non-celiac gluten sensitivity
Biliary colic
Kidney stone
Cirrhosis
Abdominal irradiation

Outside the abdomen
Cardiopulmonary

Cardiomyopathy
Myocardial infarction (heart attack)
Paroxysmal coughInner-ear diseases

Motion sickness
Labyrinthitis
MalignancyIntracerebral disorders

Malignancy
Hemorrhage
Abscess
Hydrocephalus
Meningitis
Encephalitis
RabiesPsychiatric illnesses

Anorexia and bulimia nervosa
DepressionOther

Post-operative vomiting
Nociception

Medications and metabolic disorders
Drugs

Chemotherapy
Antibiotics
Antiarrhythmics
Digoxin
Oral hypoglycemic medications
Oral contraceptivesEndocrine/metabolic disease

Pregnancy
Uremia
Ketoacidosis
Thyroid and parathyroid disease
Adrenal insufficiencyToxins

Liver failure
Alcohol

Pathophysiology
Research on nausea and vomiting has relied on using animal models to mimic the anatomy and neuropharmacologic features of the human body. The physiologic mechanism of nausea is a complex process that has yet to be fully elucidated. There are four general pathways that are activated by specific triggers in the human body that go on to create the sensation of nausea and vomiting. Central nervous system (CNS): Stimuli can affect areas of the CNS including the cerebral cortex and the limbic system. These areas are activated by elevated intracranial pressure, irritation of the meninges (i.e. blood or infection), and extreme emotional triggers such as anxiety. The supratentorial region is also responsible for the sensation of nausea. Chemoreceptor trigger zone (CTZ): The CTZ is located in the area postrema in the floor of the fourth ventricle within the brain.