Mechanistic approach

• Reduced gastric motility
  • Pro-kinetic agents are useful in these scenarios as the nausea and vomiting is usually resulting from gastric dysmotility and stasis
  • According to NICE CKS and BMJ best practice, first-line medications include metoclopramide and domperidone
  • However, NICE CKS indicate that metoclopramide should not be used when pro-kinesis may negatively affect the gastrointestinal tract, particularly in complete bowel obstruction, gastrointestinal perforation, or immediately following gastric surgery
• Chemically mediated
  • If possible, the chemical disturbance should be corrected first
  • In the context of other chemically mediated syndromes, for example due to opioid medications, there are a number of suggested medications
  • Key treatment options include ondansetron, haloperidol and levomepromazine
• Visceral/serosal causes
  • Cyclizine and levomepromazine are first-line
  • Anti-cholinergics such as hyoscine can be useful
• Raised intra-cranial pressure
  • The NICE CKS guidelines recommend using cyclizine for nausea and vomiting due to intracranial disease
  • Dexamethasone can also be used
  • Radiotherapy can be considered if there is likely raised intra-cranial pressure due to cranial tumours
• Vestibular
  • NICE CKS and BMJ best practice recommends use of cyclizine as a first-line treatment in disorders due to the vestibular system
  • Refractory vestibular causes of nausea and vomiting can be treated alternatively with metoclopramide or prochlorperazine
  • Atypical antipsychotics such as olanzapine or risperidone can be used in refractory cases according to UptoDate
• Cortical
  • If anticipatory nausea is the clear cause, a short acting benzodiazepine such as lorazepam can be useful
  • If benzodiazepines are not ideal, BMJ best practice recommends use of cyclizine
  • Ondansetron and metoclopramide can also be trialled