An antipsychotic used for schizophrenia and a specific delusional condition
Pimozide
An antipsychotic tablet used for schizophrenia and a specific delusional condition, which needs heart-rhythm monitoring.
What is Pimozide?
Pimozide is an older antipsychotic medicine taken by mouth for schizophrenia and for a condition called monosymptomatic hypochondriacal psychosis, where someone has a fixed false belief about their body. The most important thing to know is that it can affect the heart's electrical rhythm (the QT interval), which can lead to serious, sometimes dangerous, heart-rhythm problems, so an ECG (heart tracing) is needed before and during treatment. It can also cause movement side effects. It interacts with many other medicines that also affect the heart rhythm, so a full medicines list is essential.
Education and reference only. This is a plain-language guide to Pimozide — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Pimozide is an antipsychotic medicine, a type of treatment used to calm overactive signalling in the brain. It is used for schizophrenia, a long-term mental-health condition that can cause hallucinations, delusions and disordered thinking, and for monosymptomatic hypochondriacal psychosis, where a person holds a single fixed false belief about their body. It is taken by mouth as a tablet, usually once a day. It is an older medicine and is used less often now, partly because of its effects on the heart's rhythm, so it is prescribed and supervised carefully, with heart tracings to check it is safe.
How it works
Pimozide works mainly by blocking dopamine, a chemical messenger in the brain that, when overactive, is linked to symptoms such as delusions and hallucinations. By dampening this signalling, it helps reduce these symptoms over time. Because it is long-acting, it is usually taken once a day. Importantly, pimozide also affects the heart's electrical system, slightly lengthening the part of the heartbeat known as the QT interval, which is why heart tracings are needed and why it is kept apart from other medicines that do the same thing.
Company & origin
Originated / developed by: Generic (long-established).
An older antipsychotic used in the UK for schizophrenia and for monosymptomatic hypochondriacal psychosis, prescribed with careful heart monitoring.
What it treats
Conditions Pimozide is used for
Practical use
How to take Pimozide
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth once a day, or as your prescriber directs, at about the same time each day.
- Attend the heart tracings (ECGs) and blood tests you are asked to have, as these check it is safe for your heart.
- Give every prescriber and pharmacist your full medicines list, as pimozide must not be combined with many heart-rhythm medicines.
- Do not stop it suddenly; talk to your prescriber first, as stopping abruptly can let symptoms return.
- Report any fainting, palpitations, muscle stiffness, tremor or restlessness promptly.
Weighing it up
Advantages & disadvantages of Pimozide
Advantages
- Can help control symptoms of schizophrenia and a specific delusional condition.
- Taken by mouth as a once-daily tablet.
- A long-established medicine with decades of clinical experience.
Disadvantages
- Can affect the heart's rhythm (the QT interval) and, rarely, cause serious heart-rhythm problems, so it needs ECG monitoring.
- Interacts with many other medicines, particularly those that affect the heart rhythm.
- Can cause movement side effects such as stiffness, tremor or restlessness.
Practical use
Good to know
The most important safety point with pimozide is its effect on the heart's electrical rhythm: it can lengthen the QT interval, which in some people can lead to serious heart-rhythm disturbances. Because of this, a heart tracing (ECG) is done before starting and during treatment, and it must not be combined with many other medicines that also affect the heart rhythm. Tell every prescriber and pharmacist that you take it. Like other antipsychotics, it can cause movement side effects such as stiffness, tremor, restlessness or slow movements, which should be reported. It can also cause drowsiness, weight changes and, by raising a hormone called prolactin, effects such as breast tenderness or changes in periods. It should not be stopped suddenly without advice, as symptoms can return.
Who should not take it / use with caution
- People who have had a serious allergic reaction to pimozide should not take it.
- It should not be used by people with certain heart-rhythm problems, a prolonged QT interval, or a family history of sudden heart problems.
- It is used with great caution alongside other medicines that affect the heart's rhythm, and these combinations are often avoided.
- It is used with care in the elderly and in people with heart disease or certain electrolyte imbalances.
Monitoring
- Heart tracings (ECGs) before and during treatment to check the QT interval.
- Reviewing for movement side effects, drowsiness and how well symptoms are controlled.
- Checking weight, and blood tests including electrolytes and prolactin where appropriate.
Side effects
- Drowsiness, and movement effects such as stiffness, tremor, restlessness or slowed movements.
- Changes in the heart's rhythm (the QT interval), which is why ECGs are done.
- Weight changes, and hormone effects such as breast tenderness or changes in periods.
- Rarely but seriously, dangerous heart-rhythm disturbances, or a severe reaction with high fever and muscle stiffness, which need urgent medical attention.
Key interactions
- It must not be combined with many medicines that also lengthen the heart's QT interval, as this raises the risk of dangerous rhythms.
- Some medicines, including certain antibiotics and antifungals, can raise pimozide levels and must be avoided.
- Conditions or medicines that lower potassium can add to the heart-rhythm risk, so these are watched.
Available as: Tablets taken by mouth.
Answers
Pimozide: frequently asked questions
What is pimozide used for?
It is an antipsychotic used for schizophrenia and for monosymptomatic hypochondriacal psychosis, a condition where someone holds a single fixed false belief about their body.
Why do I need heart tracings?
Pimozide can lengthen the heart's QT interval and, rarely, cause serious heart-rhythm problems, so ECGs are done before and during treatment to keep it safe.
Why does my medicines list matter so much?
Pimozide must not be combined with many other medicines, especially those that affect the heart rhythm, so every prescriber and pharmacist needs your full list.
Can it cause movement problems?
Yes, like other antipsychotics it can cause stiffness, tremor, restlessness or slowed movements; report these so your treatment can be reviewed.
Can I stop it suddenly?
No. Stopping suddenly can let symptoms return, so any change should be made gradually and on your prescriber's advice.
The wider class
About Antipsychotic (oral)
Pimozide belongs to the antipsychotic (oral) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
Browse by body system
Authoritative sources
- BNF
- NICE CKS
Building a medicines information resource?
We create evidence-led, dose-free drug and formulary references for teams.