Clozapine Counselling – OSCE Guide

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This article provides a step-by-step approach to counselling patients about clozapine in an OSCE setting.

Opening the consultation

Wash your hands and don PPE if required.

Introduce yourself including your name and role.

Confirm the patient’s name and date of birth.

Explain the reason for the consultation: “Today I’d like to talk to you about a medication called clozapine, would that be ok?”.

It is important to establish a good rapport and an open line of communication with the patient early in the consultation: “If you have any questions at any point, or if something is not clear, please feel free to interrupt and ask me.”

Make sure to check the patient’s understanding at regular intervals throughout the consultation and provide opportunities to ask questions (this is often referred to as ‘chunking and checking’).

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Ideas, concerns and expectations

A key component of counselling involves exploring a patient’s ideasconcerns and expectations (often referred to as ICE).

Asking about a patient’s ideas, concerns and expectations can provide insight into how a patient currently perceives their situation, what they are worried about and what they expect from the consultation. It can sometimes be challenging to use the ICE structure in a way that sounds natural in your consultation, but we have provided some examples for each of the three areas below. 


  • “Have you heard of clozapine?”
  • “Before we start, are you able to please take me through what you know about clozapine already?”


  • “Do you have any particular worries about starting clozapine?”


  • “What were you hoping we would cover today relating to considering a trial of clozapine?”

Patient history

Although the purpose of this station is to counsel the patient, it is a good idea to gather a quickfocused history early in the consultation.

This should include exploration of the patient’s symptoms and management of schizophrenia so far including hospital admissions and previous trials of medication including impact, compliance and adverse effects.

Understanding the patient’s care so far will help you tailor any advice and personalise the information for their specific situation.

For more information, see the Geeky Medics guides to schizophrenia and exploring first-rank symptoms in a psychiatric history.

What is clozapine and when is it used?

Clozapine is an antipsychotic medication used in patients who have schizophrenia that is difficult to treat, or treatment-resistant.

This means that it is used in those who have not responded to treatment with at least two other antipsychotics (usually one first-generation and one-second generation antipsychotic) or those who have not tolerated other medication.1


“Sometimes, we find that despite trials of different medication people still struggle with some of the symptoms of schizophrenia; such as hallucinations, paranoia, disorganization or unusual beliefs. This can make it difficult for people to live the lives they would like to.”

“When people have tried at least two different antipsychotic medications and continue to experience symptoms we often refer to this as ‘difficult to treat schizophrenia’ or ‘treatment-resistant schizophrenia’.” 

How to take clozapine

Clozapine comes in tablet form, a liquid option and more recently an orodispersible form.2 It is not currently available in depot form.

Clozapine is prescribed at a low dose to start off with and this is titrated up over a period of several weeks. It is important that doses are not missed. This is because if clozapine is not taken for more than 48 hours the titration process needs to start again.3

Advantages of clozapine

Given all the information on side effects and monitoring requirements that need to be covered in the consultation, it can be easy to overlook the advantages.

Studies have shown that approximately six out of ten people with treatment-resistant schizophrenia will benefit from taking clozapine.

There is also research that demonstrated clozapine is superior to olanzapine when preventing suicide attempts in patients with schizophrenia and schizoaffective disorder.5


“In your case, I understand that things remain difficult despite you having tried two different antipsychotic medications. For people in this situation, we like to consider using another medicine called clozapine. We know that many people who have not responded to other medication will notice a significant benefit when taking clozapine. The benefits may include the improvement of distressing symptoms and improved functioning, with clozapine often helping people to be well enough to leave hospital or live independently.”

“Unfortunately, there are some important, potentially serious, side-effects to be aware of and therefore clozapine is not used straight away in all patients with schizophrenia despite it being effective. Because of these side-effects, clozapine requires increased tests and monitoring which I was hoping to cover with you today.”

Side effects

Side effects can be split into common side effects and rarer but more serious side effects.

Common side effects

Common side effects and their management include:3,6

  • Sedation: may improve with time but can consider night-time dosing only
  • Constipation: bowel monitoring, high fibre diet advice and stimulant laxatives
  • Tachycardia: consider cardiology advice as persistent tachycardia could represent a cardiac complication, otherwise beta-blockers can be used
  • Weight gain: dietary advice is important, metformin has also been shown to be effective for treating clozapine-induced weight gain
  • Hypersalivation: often improves over time, if troublesome for the patient hyoscine can be used
  • Blood pressure changes: clozapine can cause both hypotension and hypertension.
  • Hyperglycaemia: may require oral hypoglycaemics or insulin.

Rare but serious side effects

Clozapine can cause a drop in white cells, specifically neutrophils which are responsible for fighting infections within the body. A small drop in these numbers of cells is called neutropenia, which affects approximately 3% of those taking clozapine, and a more significant drop is called agranulocytosis which occurs in fewer than 1%.4

Due to this risk and the subsequent risk of developing a severe infection, there are strict monitoring protocols for patients taking clozapine. Patients also need to be advised to seek urgent medical assessment if they develop flu-like symptoms.

Clozapine also lowers the seizure threshold and therefore patients can develop seizures, especially when clozapine is prescribed at higher doses. Those who require high doses are often prescribed a prophylactic anticonvulsant such as sodium valproate.3

Cardiac complications including myocarditis and cardiomyopathy have been associated with clozapine therapy. These should be considered in any patient who develops persistent tachycardia at rest, chest pain, abnormal rhythms, palpitations or evidence of heart failure.3

If cardiac complications are suspected, patients should undergo a physical examination, ECG, laboratory investigations including troponin and CRP. A cardiology opinion should be sought, and an echocardiogram may be required.

Constipation is a common side effect of clozapine due to gastrointestinal hypomotility. This puts patients at higher risk of developing an ileus and bowel obstruction.3


All antipsychotics require baseline investigations and then subsequent monitoring.

Baseline investigations

Baseline investigations usually include:7

  • ECG
  • Blood pressure and pulse
  • Calculation of body mass index (BMI)
  • Laboratory investigations: FBC, U&Es, LFTs, prolactin, HbA1c and lipids. For clozapine, a baseline troponin is also requested.

Clozapine monitoring

Due to the risk of serious side effects, clozapine requires a stricter monitoring protocol with close supervision during the initiation and titration of clozapine and regular blood tests.8

During the first 18 weeks of administration, patients are required to have their full blood count checked weekly. This changes to fortnightly after 18 weeks and then monthly after one year.8

All patients in the United Kingdom taking clozapine will be registered with the service that manufactures their type of treatment and medication will only be dispensed if blood tests are within acceptable limits

Plasma levels of clozapine are also monitored in some circumstances. This includes when poor compliance is suspected, when high doses are required and when their smoking status changes. Levels of clozapine can rise significantly with the reduction and cessation of cigarette smoking.3


“We know that in some cases people experience serious side effects when taking clozapine and it is for this reason that we carefully monitor patients taking this medication. Initially, we require some baseline investigations including your weight, height, a tracing of your heart, physical observations and blood tests. Following this, it is important that you have weekly blood tests for the first 18 weeks. The blood tests will look at the white cells in your blood, which are the cells responsible for fighting infection.”

“Rarely, clozapine will cause a drop in the number of these white cells and it is important that this is detected early. The risk is higher when clozapine is first started, and after 18 weeks the frequency of blood tests can be reduced but you will need to have regular blood tests for as long as you remain on clozapine, and for a short period afterwards if you stop it. It is important to let your care coordinator know if you experience any flu-like symptoms so we can organise for your bloods to be checked.”

“Clozapine can also rarely cause heart problems which is why a heart tracing is completed before starting with regular checks of your heart rate. If you notice any chest pain, palpitations or swollen ankles it is important to inform your care team.”

“We also know that clozapine increases the likelihood of constipation. If constipation becomes severe, people can be at risk of bowel problems. For this reason, we suggest that you monitor your bowels and can provide a stool chart if this would help. If you do notice difficulty opening your bowels, then we can prescribe or increase laxative medication.”

Closing the consultation

Close the consultation by summarising what you have discussed. This allows you to emphasise the key points of the consultation.

Finally, thank the patient for their time and offer them a leaflet summarising the key information related to clozapine. The Royal College of Psychiatrists has a patient information leaflet on antipsychotics, including clozapine. 

Dispose of PPE appropriately and wash your hands.


Dr Nwaorima Kamalu


Dr Chris Jefferies


  1. NICE. Psychosis and schizophrenia in adults: prevention and management. Published February 2014. Available from: [LINK]
  2. Choice and medication. Medication: clozapine. Accessed November 2021. Available from: [LINK]
  3. Sussex Partnership NHS Trust. Procedure and Guidance for the use of Clozapine. Published August 2015. Available from: [LINK]
  4. Rotherham Doncaster and South Humber NHS Foundation Trust. Clozapine, Information for service users and carers. Published November 2011. Available from: [LINK]
  5. Meltzer et al. Clozapine treatment for suicidality in schizophrenia: International Suicide Prevention Trial (InterSePT). Published January 2003. Available from: [LINK]
  6. Liu et al.  Metformin for treatment of clozapine-induced weight gain in adult patients with schizophrenia: a meta-analysis. Published December 2015. Available from: [LINK]
  7. NICE. Psychosis and schizophrenia: What monitoring is required?. Published September 2021. Available from: [LINK]
  8. NICE BNF. Clozapine. Accessed November 2021. Available from: [LINK]


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