UK Clinical Pharmacy Association

Chlorphenamine

Issues for surgery

Loss of symptomatic relief of pruritis, hay fever, food allergy and urticaria if omitted.

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.

Chlorphenamine 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 chlorphenamine and fentanyl.

Antimuscarinic action

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

Interactions with other common medicines used in the perioperative period

CNS depression

See also Interactions with common anaesthetic agents.

Chlorphenamine 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

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

Nefopam

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

Further information

None relevant.

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]

Summary of Product Characteristics – Piriton® (chlorphenamine) Tablets. Haleon UK Trading Limited. Accessed via www.medicines.org.uk 02/10/2023 [date of revision of the text April 2023]