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A plain-language summary of the cited sources below. Informational only — not medical advice.
Haloperidol works by blocking dopamine receptors in specific parts of the brain. Dopamine is a chemical messenger involved in regulating mood, behaviour, and movement. By blocking these receptors, haloperidol has a calming effect and can reduce symptoms such as hallucinations, delusions, confused thinking, and agitation. This action on dopamine also explains many of the medication's side effects.
Haloperidol is approved in Australia for several conditions, including schizophrenia and other psychotic disorders, severe agitation in acute alcohol withdrawal, intractable nausea and vomiting that hasn't responded to other treatments, and in palliative care settings. It may also be used for Tourette syndrome and as part of pain management in hospital settings.
After your family member takes haloperidol, it stays active in the body for quite some time — the half-life ranges from 12 to 38 hours depending on the individual and how the medication is given. This means effects and side effects can persist well beyond a single dose. The medication is broken down in the liver by enzymes called CYP3A4 and CYP2D6, which matters because other medications that affect these enzymes can change how haloperidol works in the body.
The most common side effects involve movement. Extrapyramidal reactions include muscle stiffness, tremor, restlessness (akathisia), and involuntary muscle spasms (dystonia). These parkinsonian effects can be distressing and uncomfortable. Haloperidol can also cause a drop in blood pressure when standing up, which may lead to dizziness or falls.
There are serious risks to watch for. Neuroleptic malignant syndrome is a rare but life-threatening reaction involving high fever, muscle rigidity, confusion, and unstable blood pressure. Tardive dyskinesia causes repetitive, involuntary movements that can become permanent even after stopping the medication. Haloperidol affects heart rhythm and can cause QT prolongation, which increases the risk of dangerous irregular heartbeats including a pattern called torsades de pointes. Other serious effects include severe drops in white blood cells, which increase infection risk, and pneumonia. If your family member develops a high fever, severe muscle stiffness, chest pain, irregular heartbeat, sore throat with fever, unusual bruising, or difficulty breathing, seek medical attention immediately.
Common off-label uses observed in AU practice — none of these are TGA-approved indications for this substance. If the documented purpose is one of these, the prescription falls outside the TGA-approved set and may sit inside the chemical-restraint frame depending on jurisdiction and context.
These are practitioner observations, not TGA-approved indications. A use being off-label does not by itself imply a regulated restrictive practice; review the documented purpose against the observed function in context.
Tier 4 · Observation“Although the complex mechanism of the therapeutic effect of haloperidol is not clearly established, it is known that it produces a selective effect on the central nervous system by competitive blockade of postsynaptic dopamine (D2) receptors in the mesolimbic dopaminergic system, and an increased turnover of brain dopamine to produce its tranquillising effects.”
“The plasma half-life of haloperidol after oral administration ranges from 12 to 38 hours.”
A plain-language summary of the cited sources below. Informational only — not medical advice.
Haloperidol is a butyrophenone antipsychotic that exerts its therapeutic effect through competitive blockade of postsynaptic dopamine D₂ receptors in the mesolimbic system, increasing dopamine turnover to produce tranquillising effects. TGA-approved indications include the management of psychotic disorders (schizophrenia, organic psychosis, mania), Gilles de la Tourette syndrome, acute alcoholism with delirium or aggression, intractable nausea and vomiting in malignancy or radiation therapy not responsive to other agents, neuroleptanalgesia, and use in palliative care.
The plasma half-life after oral administration ranges from 12 to 38 hours; depot formulations extend this substantially. Haloperidol is metabolised by CYP3A4 and CYP2D6, rendering it susceptible to interactions with inducers or inhibitors of those pathways. Common adverse effects include extrapyramidal reactions (akathisia, dystonia, parkinsonian effects) and orthostatic hypotension. Serious risks include neuroleptic malignant syndrome, persistent tardive dyskinesia, agranulocytosis, QT prolongation with ventricular arrhythmias including torsades de pointes, and potentially fatal bronchopneumonia.
Contraindications are extensive: comatose states, CNS depression from alcohol or other depressants, severe depression, spastic diseases, pre-existing parkinsonian symptoms or Parkinson's disease, manifest or occult basal ganglia lesions, prolactin-dependent tumours, known hypersensitivity, and clinically significant cardiac disorders including recent myocardial infarction, uncompensated heart failure, arrhythmias treated with class IA or III antiarrhythmics, QTc prolongation, history of ventricular arrhythmia or torsades de pointes, significant bradycardia, second- or third-degree heart block, and uncorrected hypokalaemia. Concomitant use with other QT-prolonging drugs is contraindicated.
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Haloperidol cannot be used in people who are in a coma or heavily sedated from alcohol or other depressants, those with severe depression, or anyone with Parkinson's disease or similar movement disorders. It's also contraindicated for people with certain heart conditions including recent heart attack, uncontrolled heart failure, specific types of irregular heartbeat, or abnormalities in heart electrical activity. People with low potassium levels or tumours affected by prolactin should not take haloperidol.
Curated subset. The full adverse-effect list is in the TGA Product Information; click any citation above to open it.
“Studies have shown that CYP3A4 and/or CYP2D6 are involved in the metabolic biotransformation of haloperidol.”