UK Clinical Pharmacy Association

Hydroxyzine

Issues for surgery

Loss of symptomatic relief of pruritis if omitted.

Risk of QT-interval prolongation if continued (see Interactions with common anaesthetic agents, Interactions with other common medicines used in the perioperative period and Further information).

Advice in the perioperative period

Elective and emergency surgery 

Continue.

Post-operative advice

If taken regularly, restart post-operatively once enteral intake resumed, otherwise restart if symptoms develop.

Interactions with common anaesthetic agents

CNS depression

See also Interactions with other common medicines used in the perioperative period.

Hydroxyzine has CNS depressant effects which may be additive with other medicines that also have CNS depressant effects such as:

  • benzodiazepines
  • inhalational anaesthetics and intravenous anaesthetics
  • local anaesthetics
  • opioids

(Consult British National Formulary for available drugs in each class)

Case reports describe increased respiratory depression with concomitant use of hydroxyzine and pethidine.

Antimuscarinic action

The antimuscarinic action of hydroxyzine may be additive with agents that also have antimuscarinic effects such as atropine and glycopyrronium.

QT-interval prolongation

Hydroxyzine prolongs the QT-interval; co-administration with other medicines known to prolong the QT-interval is contraindicated (see Further information).

Anaesthetic agents that may be used in the perioperative period that are known to, or predicted to, prolong the QT-interval include:

  • desflurane, isoflurane, sevoflurane – avoid
  • thiopental (theoretical)*

* interactions resources recommend to monitor ECG with concurrent use if risk factors for QT-prolongation are also present (increasing age, female sex, cardiac disease, and some metabolic disturbances e.g. hypokalaemia). It is a clinical decision to co-prescribe hydroxyzine and any of these medicines. See Further information.

Interactions with other common medicines used in the perioperative period

CNS depression

See also Interactions with common anaesthetic agents.

Hydroxyzine has CNS depressant effects which may be additive with other medicines that also have CNS depressant effects such as:

  • antiemetics (e.g. cyclizine, prochlorperazine)
  • opioids

(Consult British National Formulary for available drugs in each class)

Antimuscarinic action

Antiemetics

See also QT-interval prolongation below.

The antimuscarinic action of hydroxyzine may be additive with antiemetics that also have antimuscarinic effects such as cyclizine, haloperidol, levomepromazine or prochlorperazine.

Nefopam

The antimuscarinic action of hydroxyzine may be additive with nefopam which also has antimuscarinic effects.

Hypokalaemia

Dexamethasone and hydrocortisone may cause hypokalaemia (potentially increasing the risk of torsades de pointes) – monitor potassium levels. If hypokalaemia occurs, corrective action should be taken and QT-interval monitored.

QT-interval prolongation

Hydroxyzine prolongs the QT-interval; co-administration of hydroxyzine with medicines known to prolong the QT-interval is contraindicated1 (see Further information).

Medicines that may be used in the perioperative period that are known to prolong the QT-interval include:

  • ciprofloxacin*
  • clarithromycin – avoid
  • domperidone – avoid
  • droperidol – avoid
  • erythromycin (particularly intravenous) – avoid
  • granisetron*
  • haloperidol – avoid
  • loperamide*
  • ondansetron – avoid
  • prochlorperazine (theoretical risk)*

*interactions resources recommend to monitor ECG with concurrent use if risk factors for QT-interval prolongation also present (increasing age, female sex, cardiac disease, and some metabolic disturbances, e.g., hypokalaemia). It is a clinical decision to co-prescribe hydroxyzine and any of these medicines. See Further information.

Further information

MHRA/CHM advice: Risk of QT-interval prolongation and torsade de pointes (April 2015)

Following concerns of heart rhythm abnormalities, the safety and efficacy of hydroxyzine has been reviewed by the European Medicines Agency. Hydroxyzine is associated with a small risk of QT-interval prolongation and torsade de pointes; these events are most likely to occur in patients who have risk factors for QT-interval prolongation, e.g. concomitant use of drugs that prolong the QT-interval, cardiovascular disease, family history of sudden cardiac death, significant electrolyte imbalance (low plasma potassium or plasma magnesium concentrations), or significant bradycardia.

To minimise the risk of such adverse effects, the following recommendations should be followed:

  • Hydroxyzine is contra-indicated in patients with prolonged QT-interval or who have risk factors for QT-interval prolongation, this includes concomitant use of medicines known to prolong the QT-interval (please note the above interactions sections list some medications, denoted with an asterisk, which theoretically may be associated with QT-interval prolongation where interactions resources advise they can be used with caution or ECG monitoring. However, this is the clinical decision of the prescriber.
  • Avoid use in the elderly due to increased susceptibility to the side-effects of hydroxyzine.
  • Consider the risks of QT-interval prolongation and torsade de pointes before prescribing to patients taking drugs that lower heart rate or plasma-potassium concentration
  • In adults, the maximum daily dose is 100 mg.
  • In the elderly, the maximum daily dose is 50 mg (if use of hydroxyzine cannot be avoided).
  • The lowest effective dose for the shortest period of time should be prescribed.

References

Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 2nd October 2023]

Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 2nd October 2023]