Published: November 2004
ADR update

Clozapine Patients Presenting with Symptoms of Infection

Information on this subject has been updated. Read the most recent information.

Prescriber Update 25(2): 18
November 2004

The antipsychotic clozapine (Clozaril®, Clopine®) can cause potentially fatal neutropenia and agranulocytosis (number needed to harm = 59).1

Patients on clozapine who present with evidence of infection such as flu-like symptoms, sore throat or fever should be investigated for a blood dyscrasia.  This includes immediately arranging for a differential blood count, and making contact with the treating psychiatrist and mental health team.  Depending on the blood test result and clinical situation, an urgent haematology referral or emergency hospital admission may be required.

Some antibiotics (e.g. sulphonamides, trimethoprim and erythromycin) may increase the risk of neutropenia when combined with clozapine, therefore concomitant use should be avoided.2

General practitioners should be aware of safety protocols established by the psychiatrist, including the essential requirement that patients on clozapine comply with regular blood tests (weekly during the first 18 weeks of therapy and at least every four weeks thereafter for the duration of clozapine treatment).

  1. Wahlbeck K, Cheine M, Essali A, et al. Evidence of clozapine's effectiveness in schizophrenia: A systematic review and meta-analysis of randomized trials. Am J Psychiatry 1999;156:990-999.
  2. Stockley I (ed.) Stockley's Drug Interactions (6th ed.) 2002: Pharmaceutical Press, London, p.717-718.