Haloperidol — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Haloperidol?
Haloperidol is a first-generation (typical) antipsychotic used for schizophrenia, acute agitation, delirium, and Tourette syndrome. This medication is funded by Pharmac for schizophrenia, agitation, and delirium.
What is Haloperidol Used For?
Used for schizophrenia, acute agitation (IM injection), delirium in hospital settings, Tourette syndrome, intractable hiccups, and nausea/vomiting in palliative care.
How Does Haloperidol Work?
Potent dopamine D2 receptor antagonist. Blocks dopaminergic transmission in the mesolimbic system (reducing psychosis) and nigrostriatal pathway (causing extrapyramidal effects). Minimal serotonin, histamine, or muscarinic activity.
How to Take Haloperidol
Oral: 0.5–20 mg/day in divided doses. IM injection: 5 mg for acute agitation. Depot: haloperidol decanoate every 4 weeks. Take oral formulation with food. Review need for ongoing treatment regularly.
Common Side Effects of Haloperidol
- Extrapyramidal symptoms (muscle stiffness, restlessness, dystonia — more common than atypicals)
- Sedation
- Dry mouth
- Constipation
- Elevated prolactin
- QT prolongation
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Tardive dyskinesia (with long-term use — can be irreversible)
- Neuroleptic malignant syndrome
- QT prolongation and torsades de pointes
- Acute dystonic reactions (especially young patients)
- Agranulocytosis (rare)
Drug Interactions
Haloperidol may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- QT-prolonging medicines (additive risk)
- CNS depressants
- Lithium (rare encephalopathy with high lithium levels)
- Carbamazepine (reduces haloperidol levels)
New Zealand Prescribing Information
Haloperidol (0.5–10 mg tablets; 2 mg/mL liquid; 5 mg/mL injection — Haldol® and generics) and haloperidol decanoate depot are funded by Pharmac. Now mainly reserved for acute agitation, delirium, and patients intolerant of atypical antipsychotics due to its high extrapyramidal side effect burden.
Frequently Asked Questions
What is haloperidol used for in hospital?
In hospitals, haloperidol is widely used for acute delirium — particularly in ICU and surgical wards — to manage agitation and confusion, at low doses (0.5–1 mg). It is preferred because it can be given orally or by injection and has lower respiratory depression risk than benzodiazepines.
Why does haloperidol cause movement problems?
Strong D2 blockade in the nigrostriatal pathway causes extrapyramidal effects: muscle stiffness (drug-induced parkinsonism), involuntary restlessness (akathisia), and muscle spasms (dystonia). These are more common with haloperidol than with atypical antipsychotics.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: