Nausea can either be acute, or chronic, and is not always associated with vomiting. In many cases it is possible to identify a cause, although in the palliative care population nausea is frequently multifactorial.
Palliative diagnosis that frequently cause nausea and / or vomiting include intra-abdominal or gastrointestinal malignancies - especially those which result in bowel obstruction; central nervous system malignancy - which may cause raised intracranial pressure, cerebellar or vestibular symptoms; and HIV AIDS.
Other factors that contribute to nausea and / or vomiting that should be considered, and treated where possible, include:
There are no widely accepted assessment tools for nausea and vomiting in palliative care, particularly for research. Nausea must be self-assessed by patients, whereas vomiting can be monitored objectively. Nausea is routinely assessed in Australian palliative care services using Symptom Assessment Scores (SAS) which is part of the PCOC dataset.
A systematic review has identified evidence to support the use of metoclopramide and 5HT3 antagonists in advanced cancer.  Other antiemetics are frequently used in palliative care, but at present lack a strong evidence base. The choice of an antiemetic for nausea may be either empirical, or aetiological - related to the likely main mechanism of nausea and / or vomiting. There is no evidence to support one approach over the other, based on a systematic review of randomised controlled trials. 
Nausea is a common side effect of opioid use and much of the research generated on opioid-induced nausea and vomiting comes from an acute and post-operative clinical setting. A recent systematic review of nausea and vomiting associated with opioids identified limited evidence to support the practice of opioid rotation or switching.  There are guidelines recommending clinical practice for treating nausea in cancer.  There is limited specific evidence for antiemetic choice in older people or paediatrics.
Use of antiemetics is examined in more detail in a separate section as is bowel obstruction related to gastrointestinal malignancy.
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Last updated 27 August 2021