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This guideline is aimed at providing quick and general guideline on PONV. Refer to local protocols for more detailed guidance.
Nausea and vomiting is a common and distressing symptom or side effect in medicine, surgery and following anaesthesia. It can cause complications such as wound dehiscence, electrolyte imbalance, increased pain, dehydration and aspiration. Generally, uncomplicated PONV rarely goes beyond 24 hours post-operatively. Problematic PONV however is more multifactorial in origin and can be difficult to treat effectively. Patients at risk of this should be identified by the anaesthetist and may be given prophylactic anti-emetic treatment. Post-operative patients with nausea and vomiting may be considered as either failure of prophylaxis or for primary treatment.
Drug therapy
The table below is a general quick guide on the prescribing of anti-emetics, but see local guidelines.
Anti-emetic / Site of action | Dose and route of administration | Comments |
Ondansetron 5HT3 receptor antagonist | 4mg oral / IV every 8 hours | Risk of prolonged QT interval, constipation. Avoid if congenital long QT syndrome. |
Prochlorperazine Medullary chemoreceptor zone Dopamine [D2] receptor antagonist | 3–6mg buccal every 12 hours or 12.5mg deep IM as a 'one-off' dose [IM route only, not by other parenteral routes]. In elderly patients - 3mg buccal every 12 hours or 6.25mg IM as a 'one-off' dose. | Extrapyramidal side effects - dystonic reaction. Dose reduce in elderly patients due to increased susceptibility to hypotension and neuromuscular reactions. |
Cyclizine Acts on vomiting centre. Histamine [H1] receptor antagonist | 50mg oral/IM/IV every 8 hours. Avoid oral route if actively vomiting. In elderly patients - 25mg every 8 hours. | Avoid in severe heart failure, porphyria. |
Dexamethasone Site of action unknown | 4mg IV/IM single dose | Restricted for use by the acute pain team, on-call anaesthetist. Caution - acute rectal pain with IV administration. It is not licensed for PONV. |
Droperidol Mainly dopaminergic receptor antagonist in chemoreceptor trigger zone | IV dose varies – see BNF for guidance | Restricted to use by consultant anaesthetists. Third-line agent for PONV if unresponsive to other anti-emetics. Risk of QT interval prolongation. |
N.B. The side effects, cautions and contraindications mentioned in the comments section are not exhaustive. See BNF or Summary of Product Characteristics for further information. |
General notes
- Ondansetron may be used as a first-line option, consider the comments section in the table above.
- Prochlorperazine can cause extrapyramidal side effects and may not be the best choice in certain patients. Seek senior advice. It is important to note that IM doses should only be given as a 'one off' dose.
- Cyclizine parenterally may be given if ondansetron [first-line choice] or prochlorperazine are not appropriate.
- If, after regular routine observation and assessment, it is apparent that one anti-emetic is ineffective, add in another. Use one which acts by a different mechanism as a combination of two anti-emetic drugs acting at different sites may be more effective in resistant PONV [see table above].
- If it is not possible to stop opioid analgesia, consider change of opioid, and remember to prescribe simple analgesics and NSAIDs where possible. See acute pain guideline.
- For choice of anti-emetic in breastfeeding or pregnant women contact your clinical pharmacist for advice or Medicines Information department [see Appendix 6 for contact details].
- In elderly patients [>70 years] use lower doses of prochlorperazine and cyclizine [see table above].
- Intractable vomiting may have a surgical / other serious underlying cause. Senior review is recommended.
Other information
- Metoclopramide is ineffective as an anti-emetic for PONV in licensed dosage and should not be prescribed as a routine anti-emetic unless gastric stasis is the cause of the nausea. Restrict use in young adults under 20 years [especially women] to certain circumstances because of the risk of extrapyramidal side effects. Seek senior / specialist advice if necessary.
- Metoclopramide is contraindicated in gastrointestinal obstruction and should be avoided post-gastrointestinal surgery.