Haloperidol (Haldol)
Typical antipsychotic – injectable solution for acute psychosis, schizophrenia and severe agitation
Haloperidol is a potent first-generation (typical) antipsychotic medicine belonging to the butyrophenone class. Available as an injectable solution, it is used to treat acute psychosis, schizophrenia, bipolar disorder, severe agitation, delirium, and Huntington's chorea. Haloperidol is listed on the WHO Model List of Essential Medicines and has been in clinical use since the 1950s. This guide covers its uses, dosage, side effects, drug interactions and important safety information based on international guidelines.
Quick Facts
Key Takeaways
- Haloperidol is a potent dopamine D2 receptor antagonist used for acute psychosis, schizophrenia, severe agitation and delirium, and is on the WHO Essential Medicines List.
- The injectable form provides rapid onset of action (20–40 minutes) and is administered by healthcare professionals only.
- Extrapyramidal side effects (involuntary movements, muscle stiffness, tremor) are very common, affecting more than 1 in 10 patients.
- Haloperidol carries serious risks including QT prolongation, neuroleptic malignant syndrome, and increased mortality in elderly patients with dementia-related psychosis.
- It interacts significantly with many medications including lithium, certain antibiotics, antifungals, and other drugs that prolong the QT interval.
What Is Haloperidol and What Is It Used For?
Quick Answer: Haloperidol is a first-generation antipsychotic medicine that works by blocking dopamine D2 receptors in the brain. It is used to treat conditions that affect how a person thinks, feels and behaves, including schizophrenia, acute psychosis, bipolar disorder, severe agitation, and delirium. It is also used for Huntington's chorea and postoperative nausea.
Haloperidol belongs to the butyrophenone class of antipsychotic medicines and has been a cornerstone of psychiatric treatment since its introduction by Paul Janssen in 1958. It is classified as a typical (first-generation) antipsychotic and is one of the most widely studied medicines in psychiatry. The World Health Organization (WHO) includes haloperidol on its Model List of Essential Medicines, recognizing it as one of the safest and most effective medicines needed in a health system.
As an injectable solution, haloperidol is administered intramuscularly by a healthcare professional. This formulation is particularly valuable in clinical settings where rapid control of symptoms is needed, such as acute psychotic episodes, severe agitation, or delirium in hospital patients. The depot formulation (50 mg/ml haloperidol decanoate) provides long-acting intramuscular release for maintenance treatment of schizophrenia, reducing the need for daily medication.
Approved Indications
Haloperidol is approved for use in adults with conditions that affect thinking, feelings and behaviour. These include:
- Schizophrenia – a chronic mental health condition characterized by hallucinations, delusions, and disordered thinking
- Acute psychosis – sudden episodes of psychotic symptoms requiring rapid treatment
- Bipolar disorder – manic or mixed episodes with psychotic features
- Severe agitation and aggression – when a patient is extremely agitated, threatening, or violent
- Delirium – acute confusion often occurring in hospital settings, particularly in critically ill or postoperative patients
- Huntington's chorea – to help control involuntary movements associated with Huntington's disease
- Postoperative nausea and vomiting (PONV) – prevention and treatment of nausea and vomiting after surgery
These conditions may cause symptoms such as confusion, hallucinations (seeing, hearing or feeling things that are not there), delusions (believing things that are not true), extreme suspicion (paranoia), severe mood swings, extreme agitation or aggression, and uncontrolled movements. Haloperidol can be used alone or together with other medicines, and is sometimes used when other treatments have not worked or cannot be taken by mouth.
Mechanism of Action
Haloperidol works primarily by blocking dopamine D2 receptors in the mesolimbic and mesocortical pathways of the brain. This dopamine receptor blockade reduces the overactivity of dopaminergic neurotransmission that is associated with psychotic symptoms such as hallucinations and delusions. Unlike many atypical antipsychotics, haloperidol has relatively little affinity for serotonin, muscarinic, or histamine receptors, which explains its distinct side effect profile. Its strong D2 blockade makes it particularly effective against positive psychotic symptoms but also accounts for its higher risk of extrapyramidal side effects.
What Should You Know Before Taking Haloperidol?
Quick Answer: Haloperidol must not be used if you are allergic to it, have Parkinson's disease, Lewy body dementia, certain heart rhythm disorders (QT prolongation), heart failure, or untreated low potassium levels. It carries an increased mortality risk in elderly patients with dementia-related psychosis. A thorough medical assessment is required before starting treatment.
Contraindications
Haloperidol must not be used in the following situations. You should inform your doctor about your complete medical history before receiving this medicine:
- Allergy to haloperidol or any of the other ingredients in the medicine
- Reduced consciousness – if you are less aware of your surroundings and your reactions are unusually slow
- Parkinson's disease – haloperidol blocks dopamine, which can severely worsen Parkinson's symptoms
- Lewy body dementia – patients with this type of dementia are extremely sensitive to antipsychotics
- Progressive supranuclear palsy (PSP) – a rare neurological condition
- QT prolongation or other heart rhythm problems visible on an ECG (electrocardiogram)
- Heart failure or recent heart attack (myocardial infarction)
- Uncorrected low potassium levels (hypokalaemia) in the blood
- Concurrent use of medicines that are known to prolong the QT interval (see Drug Interactions section)
Warnings and Precautions
Haloperidol can cause heart rhythm problems, movement disorders (extrapyramidal symptoms), and a potentially life-threatening condition called neuroleptic malignant syndrome. It can also cause severe allergic reactions and blood clots. You must be aware of these serious side effects as you may need immediate medical attention. See the Side Effects section for full details.
A small increase in deaths and strokes has been reported in elderly patients with dementia who take antipsychotic medicines. Haloperidol is not approved for treating dementia-related behavioural disturbances. Talk to your doctor before receiving haloperidol if you are elderly, especially if you have dementia.
Tell your doctor before receiving haloperidol if you have any of the following conditions, as your dose may need to be adjusted or additional monitoring may be required:
- Slow heart rate, heart disease, or a family history of sudden cardiac death
- Low blood pressure or dizziness when standing up (orthostatic hypotension)
- Low potassium or magnesium levels (electrolyte imbalances) – your doctor will decide how to treat this before starting haloperidol
- History of stroke or cerebrovascular disease, or if you have been told you are at increased risk of stroke
- Epilepsy or a history of seizures – haloperidol may lower the seizure threshold
- Kidney, liver or thyroid problems – dose adjustments may be needed
- High prolactin levels or prolactin-dependent cancers (such as some breast cancers)
- History of blood clots (venous thromboembolism) or a family history of blood clots
- Depression or bipolar disorder – haloperidol may worsen depressive symptoms
Medical Monitoring
Your doctor may perform an electrocardiogram (ECG) before or during treatment with haloperidol to check for heart rhythm abnormalities, particularly QT prolongation. Blood tests may also be conducted to monitor your potassium and magnesium levels before and during treatment. Regular clinical assessments will be performed to monitor for extrapyramidal symptoms, tardive dyskinesia, and other adverse effects.
Use in Children and Adolescents
Haloperidol injection should not be used in children and adolescents under 18 years of age. This is because it has not been adequately studied in these age groups for this formulation. Oral haloperidol may be used in some paediatric populations under specialist supervision in certain countries.
Pregnancy and Breastfeeding
If you are pregnant, think you may be pregnant, or are planning to have a baby, ask your doctor for advice. Your doctor may advise you not to use haloperidol during pregnancy unless clearly necessary. Newborn babies whose mothers used haloperidol during the last 3 months of pregnancy (third trimester) may experience muscle tremors or stiffness, sleepiness, restlessness, breathing difficulties, or feeding problems. If you used haloperidol during pregnancy and your baby develops any of these symptoms, contact your doctor immediately.
Tell your doctor if you are breastfeeding or planning to breastfeed. Small amounts of haloperidol can pass into breast milk. Your doctor will discuss the risks and benefits of breastfeeding while using haloperidol and help you decide the best course of action for you and your baby.
Haloperidol may increase levels of the hormone prolactin, which can affect fertility in both men and women. In women, this may cause irregular or absent menstrual periods; in men, it may contribute to erectile dysfunction or decreased libido. Talk to your doctor if you have concerns about fertility.
Driving and Operating Machinery
Haloperidol can affect your ability to drive and operate machinery. Side effects such as drowsiness can impair your alertness, particularly at the start of treatment or after a dose increase. You should not drive or use any tools or machinery until you have discussed this with your doctor and understand how haloperidol affects you personally.
Alcohol
Drinking alcohol while using haloperidol can make you feel drowsy and less alert. The sedative effects of both substances are additive, meaning that the combination can impair your judgement, coordination and reaction time more than either substance alone. Talk to your doctor about drinking alcohol while using haloperidol.
How Does Haloperidol Interact with Other Drugs?
Quick Answer: Haloperidol has clinically significant interactions with many medicines. It must not be combined with drugs that prolong the QT interval (such as certain antiarrhythmics, antibiotics and other antipsychotics). It requires careful monitoring when used with lithium. Many other medicines can increase or decrease haloperidol blood levels, potentially affecting efficacy or increasing side effects.
Haloperidol interacts with a wide range of medicines. Some interactions are dangerous and the combination is strictly contraindicated, while others require dose adjustment or careful monitoring. It is essential to tell your doctor about all medicines you are taking, including over-the-counter medicines, herbal remedies, and supplements. The following tables summarize the most important drug interactions.
Major Interactions (Contraindicated or Avoid Combination)
Do not use haloperidol if you are taking any of the following medicines, as the combination may cause dangerous heart rhythm problems (QT prolongation and torsade de pointes):
| Drug Category | Examples | Risk |
|---|---|---|
| Antiarrhythmics | Amiodarone, dofetilide, disopyramide, dronedarone, ibutilide, quinidine, sotalol | QT prolongation, fatal cardiac arrhythmias |
| Antidepressants (certain SSRIs) | Citalopram, escitalopram | QT prolongation |
| Other antipsychotics | Pimozide, sertindole, thioridazine, ziprasidone | QT prolongation, cardiac arrhythmias |
| Antibiotics | Azithromycin, clarithromycin, erythromycin, levofloxacin, moxifloxacin | QT prolongation |
| Antifungals | Pentamidine | QT prolongation |
| Antimalarials | Halofantrine | QT prolongation |
| Antiemetics | Dolasetron | QT prolongation |
| Cancer medicines | Toremifene, vandetanib | QT prolongation |
| Other | Bepridil, methadone | QT prolongation, cardiac risk |
Lithium Interaction
If you are taking lithium and haloperidol together, special monitoring is needed. Tell your doctor immediately and stop taking both medicines if you experience unexplained fever, uncontrolled movements, confusion, disorientation, headache, balance problems, or excessive drowsiness. These may be signs of a serious condition called encephalopathic syndrome.
Medicines That Affect Haloperidol Levels
The following medicines can increase or decrease haloperidol levels in your blood, potentially requiring dose adjustments. Tell your doctor if you are taking any of these:
| Medicine | Category | Effect on Haloperidol |
|---|---|---|
| Fluoxetine, paroxetine, sertraline, fluvoxamine | Antidepressants (SSRIs) | May increase haloperidol levels (CYP2D6 inhibition) |
| Venlafaxine, duloxetine, nefazodone | Antidepressants (SNRIs/other) | May increase haloperidol levels |
| Carbamazepine, phenobarbital, phenytoin | Antiepileptics | May decrease haloperidol levels (CYP3A4 induction) |
| Rifampicin | Antibiotic | May significantly decrease haloperidol levels |
| Itraconazole, posaconazole, voriconazole | Antifungals | May increase haloperidol levels (CYP3A4 inhibition) |
| Ritonavir, indinavir, saquinavir | HIV antivirals | May increase haloperidol levels |
| Bupropion | Antidepressant / smoking cessation | May increase haloperidol levels |
| Alprazolam, buspirone | Anxiolytics | May interact with haloperidol effects |
| St John's Wort (Hypericum perforatum) | Herbal remedy | May decrease haloperidol levels |
| Verapamil | Calcium channel blocker | May increase haloperidol levels |
Medicines Affected by Haloperidol
Haloperidol can also affect how other medicines work. Tell your doctor if you are taking any of the following, as dose adjustments may be necessary:
- Sedatives and sleeping pills – haloperidol can increase their sedative effects
- Strong painkillers (opioids) – increased sedation and respiratory depression risk
- Tricyclic antidepressants – haloperidol may increase their blood levels
- Blood pressure-lowering medicines (e.g. guanethidine, methyldopa) – haloperidol may reduce their effectiveness or cause additive hypotension
- Adrenaline (epinephrine) – haloperidol may block its blood pressure-raising effect
- Stimulant medicines for ADHD or narcolepsy – haloperidol may reduce their effectiveness
- Levodopa and other anti-Parkinson medicines – haloperidol directly opposes their dopaminergic action
- Anticoagulant phenindione – haloperidol may affect its blood-thinning action
What Is the Correct Dosage of Haloperidol?
Quick Answer: For adults receiving intramuscular haloperidol, the starting dose is usually 1–5 mg. Additional doses may be given at 1–4 hour intervals as needed, with a maximum total daily dose of 20 mg. Elderly patients start at half the lowest adult dose, with a usual maximum of 5 mg daily. Haloperidol injection is always administered by a healthcare professional.
Your doctor will determine how much haloperidol you need and how long the treatment should last. It may take some time before you feel the full effect of the medicine. Your doctor will usually start with a low dose and then adjust it to suit you. Your haloperidol dose will depend on your age, the condition being treated, whether you have kidney or liver problems, and what other medicines you are taking.
Adults
Standard Adult Dosing (Intramuscular Injection)
- Starting dose: 1–5 mg per injection
- Repeat doses: Additional doses may be given, usually 1–4 hours apart
- Maximum daily dose: 20 mg total in 24 hours
- Depot formulation (Haldol Depot): For long-term maintenance in schizophrenia, administered every 4 weeks by deep intramuscular injection. Dose individually determined by the treating physician
Children and Adolescents
Haloperidol injection should not be used in children and adolescents under 18 years of age. This is because it has not been sufficiently studied in this age group for this specific formulation.
Elderly Patients
Elderly Dosing (Intramuscular Injection)
- Starting dose: Half the lowest adult dose (i.e. approximately 0.5–2.5 mg)
- Dose adjustment: Gradually increased until the doctor finds the dose that works best
- Maximum daily dose: 5 mg total, unless the doctor determines a higher dose is necessary
Elderly patients are more susceptible to side effects, particularly orthostatic hypotension (low blood pressure when standing), sedation, and extrapyramidal symptoms. Careful dose titration and regular monitoring are essential in this population.
Patients with Liver or Kidney Impairment
Patients with liver or kidney problems may require reduced doses of haloperidol, as the medicine is primarily metabolized in the liver. Your doctor will assess your organ function and adjust your dose accordingly. More frequent monitoring may be needed in patients with hepatic or renal impairment.
How Haloperidol Is Given
You will receive haloperidol from a doctor or nurse. It is administered as an intramuscular injection – an injection into a muscle (usually the buttock or thigh). Since a healthcare professional administers the medicine, it is unlikely that you will miss a dose or receive too much. If you have concerns, talk to your doctor or nurse.
Missed Dose
Because haloperidol injection is given by a healthcare professional in a clinical setting, missed doses are uncommon. If you are receiving regular depot injections and miss an appointment, contact your doctor as soon as possible to reschedule.
Overdose
If too much haloperidol is given, symptoms may include severe drowsiness, low blood pressure, extrapyramidal symptoms (severe muscle stiffness, tremor), seizures, and cardiac arrhythmias. In serious cases, overdose can cause coma or be life-threatening. If overdose is suspected, seek immediate emergency medical help by calling your local emergency number.
Stopping Treatment
Unless your doctor decides otherwise, haloperidol treatment will be reduced gradually rather than stopped suddenly. Abrupt discontinuation may cause withdrawal symptoms such as nausea, vomiting, and difficulty sleeping (insomnia). Always follow your doctor's instructions carefully regarding dose reduction and discontinuation.
What Are the Side Effects of Haloperidol?
Quick Answer: The most common side effects of haloperidol (affecting more than 1 in 10 people) are extrapyramidal symptoms (involuntary movements, muscle stiffness, tremor, restlessness), agitation, insomnia and headache. Serious but less common side effects include QT prolongation, neuroleptic malignant syndrome, tardive dyskinesia, and blood clots. Seek immediate medical attention for any cardiac symptoms, high fever with muscle rigidity, or signs of blood clots.
Like all medicines, haloperidol can cause side effects, although not everybody gets them. Some side effects are serious and require immediate medical attention. It is important to be aware of these so you know when to seek emergency help.
Serious Side Effects – Seek Immediate Medical Help
Haloperidol can cause abnormal heart rhythms that prevent the heart from working properly and may cause loss of consciousness. Abnormally fast heartbeats and extra heartbeats may also occur. Heart problems are uncommon (up to 1 in 100 people). Sudden death has occurred in patients taking this medicine. Cardiac arrest has been reported with antipsychotic medicines. Seek immediate medical attention if you experience palpitations, dizziness, fainting, or chest pain.
This is a rare (up to 1 in 1,000 people) but potentially life-threatening condition causing very high fever, severe muscle rigidity, confusion, and loss of consciousness. If you develop unexplained high fever with muscle stiffness and altered consciousness, seek emergency medical help immediately.
Blood clots in veins, particularly in the legs (deep vein thrombosis – DVT), have been reported with antipsychotic medicines. Signs include swelling, pain and redness in the leg. A blood clot can travel to the lungs causing chest pain and breathing difficulties (pulmonary embolism). Seek immediate medical attention if you notice any of these symptoms.
Side Effects by Frequency
Very Common
May affect more than 1 in 10 people
- Extrapyramidal symptoms: involuntary movements (including of the mouth, tongue, jaw, and limbs), muscle stiffness, tremor, slow or reduced body movements, jerking or twisting movements, restlessness, difficulty sitting still, inability to move, reduced facial expressions
- Agitation and feeling restless
- Insomnia (difficulty sleeping)
- Headache
Common
May affect up to 1 in 10 people
- Psychotic symptoms (delusions, hallucinations) – especially at treatment initiation
- Depression
- Abnormal muscle tension (dystonia)
- Dizziness, especially when standing up
- Drowsiness and sedation
- Involuntary eye movements or upward rolling of eyes
- Visual disturbances, including blurred vision
- Low blood pressure (hypotension)
- Nausea and vomiting
- Constipation
- Dry mouth or increased saliva production
- Skin rash
- Difficulty urinating or emptying the bladder
- Erectile dysfunction (impotence)
- Weight gain or weight loss
- Changes in liver function test results
Uncommon
May affect up to 1 in 100 people
- Blood cell effects – low counts of all blood cells, including serious reduction in white blood cells and low platelet count
- Confusion
- Loss of sex drive or decreased libido
- Seizures (convulsions)
- Muscle stiffness and joint stiffness
- Muscle spasms, twitching, or uncontrollable contractions (including neck spasms)
- Difficulty walking (gait disturbance)
- Shortness of breath (dyspnoea)
- Liver inflammation (hepatitis) or jaundice (yellowing of skin and eyes)
- Increased skin sensitivity to sunlight (photosensitivity)
- Itching (pruritus)
- Excessive sweating (hyperhidrosis)
- Changes in menstrual cycle (absent or irregular periods)
- Unexpected breast milk production (galactorrhoea)
- Breast pain or discomfort
- High body temperature (hyperthermia)
- Swelling due to fluid retention (oedema)
Rare
May affect up to 1 in 1,000 people
- Elevated prolactin hormone levels (hyperprolactinaemia)
- Narrowing of airways in the lungs causing breathing difficulties (bronchospasm)
- Difficulty or inability to open the mouth (trismus)
- Sexual dysfunction
Frequency Not Known
Cannot be estimated from available data
- Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
- Low blood sugar (hypoglycaemia)
- Swelling around the voice box or spasms of the vocal cords (can impair speech and breathing)
- Sudden liver failure
- Decreased bile flow (cholestasis)
- Skin peeling or flaking
- Small blood vessel inflammation causing skin rash with small red or purple bumps (leukocytoclastic vasculitis)
- Muscle tissue breakdown (rhabdomyolysis)
- Persistent and painful erection (priapism)
- Breast enlargement in men (gynaecomastia)
- Low body temperature (hypothermia)
Reporting Side Effects
It is important to report suspected side effects after the medicine has been approved, as this allows ongoing monitoring of its benefit-risk balance. Healthcare professionals and patients can report side effects to their national pharmacovigilance authority (for example, the FDA MedWatch programme in the United States, the Yellow Card Scheme in the United Kingdom, or the EMA EudraVigilance system in Europe).
How Should You Store Haloperidol?
Quick Answer: Store haloperidol out of sight and reach of children. Do not use after the expiry date. Store in the original packaging to protect from light. Dispose of unused medicines properly through your pharmacy – do not throw them in household waste or pour down drains.
- Keep this medicine out of the sight and reach of children at all times
- Do not use after the expiry date stated on the label and carton (after EXP). The expiry date refers to the last day of that month
- Store in the original packaging to protect from light, as haloperidol is light-sensitive
- Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to dispose of medicines you no longer use. These measures help to protect the environment
What Does Haloperidol Contain?
Quick Answer: Each millilitre of Haloperidol injection contains 5 mg of the active ingredient haloperidol. The other ingredients are lactic acid and water for injections. The depot formulation contains 50 mg/ml of haloperidol decanoate in sesame oil.
Active Ingredient
The active substance is haloperidol. One millilitre of injection solution contains 5 mg haloperidol. The depot formulation (Haldol Depot) contains 50 mg/ml haloperidol decanoate, a long-acting ester of haloperidol.
Other Ingredients
The standard injection solution contains lactic acid and water for injections. The depot formulation uses sesame oil as a vehicle for sustained intramuscular release.
Appearance and Pack Sizes
Haloperidol injection is a clear, colourless solution without visible particles. It is supplied in amber glass ampoules containing 1 ml of solution, available in pack sizes of 1, 5, 30 (3 packs of 10), or 50 (10 packs of 5) ampoules. Not all pack sizes may be marketed in all countries.
Frequently Asked Questions About Haloperidol
Medical References
All medical information on this page is based on peer-reviewed research and international clinical guidelines. The following references were used in the preparation of this article:
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List. Geneva: WHO; 2023. Haloperidol is included as an essential medicine for psychotic disorders.
- European Medicines Agency (EMA). Summary of Product Characteristics: Haloperidol. EMA; 2023. European regulatory prescribing information for haloperidol.
- National Institute for Health and Care Excellence (NICE). Clinical Guideline CG178: Psychosis and schizophrenia in adults – prevention and management. NICE; 2014 (updated 2024).
- British National Formulary (BNF). Haloperidol monograph. London: BMJ Group and Pharmaceutical Press; 2025.
- US Food and Drug Administration (FDA). Haldol (haloperidol) Prescribing Information. FDA-approved labelling.
- Leucht S, Cipriani A, Spineli L, et al. Comparative efficacy and tolerability of 15 antipsychotic drugs in schizophrenia: a multiple-treatments meta-analysis. Lancet. 2013;382(9896):951–962. doi:10.1016/S0140-6736(13)60733-3
- Maudsley Prescribing Guidelines in Psychiatry. 14th ed. Chichester: Wiley; 2021. Evidence-based prescribing guidance for psychiatric medicines.
- American Psychiatric Association. Practice Guidelines for the Treatment of Patients with Schizophrenia. 3rd ed. APA; 2020.
- Haddad PM, Anderson IM. Antipsychotic-related QTc prolongation, torsade de pointes and sudden death. Drugs. 2002;62(11):1649–1671.
- Gill SS, Bronskill SE, Normand SL, et al. Antipsychotic drug use and mortality in older adults with dementia. Ann Intern Med. 2007;146(11):775–786.
About This Article
Specialists in Clinical Pharmacology, Psychiatry and Emergency Medicine
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