There are several causes of nausea and/or vomiting, which may occur simultaneously and have reciprocal enhancing effects. Multiple causative factors are evident in 25% of cases. A clear cause cannot be found in 25-33% of cases.

Known causes include the following:

  1. Delayed gastric emptying (35 - 44%)
    • gastroparesis as a result of abnormal gastric motor function:
      • tumour invasion (gastric carcinoma, metastasis from elsewhere)
      • after partial or total gastrectomy
      • as part of the anorexia-cachexia syndrome
      • paraneoplastic autonomic neuropathy
      • medication (including opioids, anticholinergic agents, vinca alkaloids, cisplatin, calcium blockers)
      • comorbidity (e.g. diabetes mellitus, renal failure, amyloidosis, scleroderma)
    • decreased gastric capacity caused by gastric carcinoma or compression due to hepatomegaly, extragastric tumours or ascites
    • pyloric or duodenal obstruction, e.g. as a result of a pancreatic carcinoma
    • gastritis or ulcer
      • peptic
      • drug-related: aspirin, NSAIDs, dexamethasone, mucolytic agents, antibiotics, iron preparations
      • radiotherapy of the spine or stomach in which the stomach lies within the radiation field
  2. Other abdominal causes (24-32%)
    • constipation
    • infiltration or traction of the mesenterium or peritoneum caused by carcinomatous peritonitis (with or without ascites)
    • ileus (due to obstruction, pseudo-obstruction, adhesions, faecal impaction, acute bacterial peritonitis or sepsis)
    • liver metastases (caused by hepatomegaly and/or metabolic abnormalities or icterus)
    • congested liver associated with heart failure
    • reflux
    • dumping syndrome after gastric resection
    • gastroenteritis, pancreatitis, cholecystitis, cholangitis, hepatitis, cystitis
    • gall stones, kidney stones
    • recent surgery
    • cough or hiccups leading to reflectory vomiting
  3. Chemical/metabolic causes (30-33%)
    • medications:
      • opioids (especially shortly after starting or after a dose increase)
        These agents may cause nausea and/or vomiting via different mechanisms: activation of the chemoreceptor trigger zone, delayed gastric emptying (see point 1) and vestibular (see point 5)
      • chemotherapeutic agents
        Nausea and/or vomiting can be acute (within 24 hours after administration) or delayed (more than 24 hours after administration); it is likely that different mechanisms play a role . 
      • The incidence of nausea and vomiting is highly dependent on the dose and type of chemotherapeutic agents used. A distinction is made between highly emetogenic chemotherapy (>90% chance of vomiting without anti-emetics), moderately emetogenic chemotherapy (30-60%) and low or not emetogenic chemotherapy (<30%).
        Other factors that may increase the chance of nausea and/or vomiting occurring after chemotherapy are: female gender, young age, sensitivity to nausea (e.g. during pregnancy or in the case of motion sickness or sea sickness), fear/stress and prior poor experiences with chemotherapy
      • tyrosine kinase inhibitors (including sunitinib, sorafenib, imatinib, erlotinib)
      • other medications (including anti-epileptic agents, theophylline, digoxin, SSRIs, anaesthetics)
    • electrolyte disorders (hypercalcaemia and hyponatraemia)
    • acute or chronic renal insufficiency
    • liver failure
    • dysregulated diabetes mellitus
    • bacterial toxins and sepsis
  4. Cerebral/psychogenic causes (7%)
    • brain metastases or primary brain tumour with increased intracranial pressure
    • leptomeningeal metastases
    • meningitis (infectious, chemical)
    • stroke
    • total cranial irradiation
    • influences relating to smell and taste
    • severe pain
    • anxiety and stress
    • anticipatory nausea and vomiting: through classical conditioning, stimuli associated with the original stimulus by means of time or place (e.g. chemotherapy) can induce nausea or vomiting
  5. Vestibulary causes (very rare in the palliative phase):
    • pharmacological (opioids, aspirin)
    • labyrinth disorders: motion sickness, Ménière's disease, neuritis vestibularis or labyrinthitis
    • tumour of the inner or middle ear/base of skull