Management of Post-operative Nausea and Vomiting (PONV)

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.

Assessment / monitoring

  • Regularly use PONV score to assess patient (scoring varies across NHSGGC hospitals).
  • Assess hydration and perfusion
  • Assess gastric emptying or paralytic ileus – consider nasogastric (NG) tube.
  • Seek cause of PONV. Is it:
    • Inadequate pain relief, infection, hypovolaemia, hypoxia, hypotension, anxiety, removal or insertion of NG tube?
    • Has enough primary anti-emetic been given? Check both anaesthetic and prescription charts.

General Management

  • Minimise patient movement.
  • Ensure analgesia is adequate – see General Principles of Acute Pain Management guideline.
  • Ensure good oxygenation and normal blood pressure.
  • Give IV fluids if dehydrated.
  • Administer anti-emetic early when patient is nauseated rather than waiting for patient to vomit before treating PONV (see drug therapy section below).
  • If cause of PONV is known, correct if possible. For instance, post-operative opioids increase patient's risk of PONV so, where possible, consider other analgesics.

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 


5HT3 receptor antagonist

4mg oral / IV every 8 hours

Risk of prolonged QT interval, constipation.

Avoid if congenital long QT syndrome.



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.


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.


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.


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.


Guideline last reviewed and updated November 2020