Haloperidol is a butyrophenone-derivative antipsychotic agent.1, 2, 3, 4 The drug is considered a conventional or first-generation antipsychotic agent.1, 2, 3, 4
Haloperidol is used orally and parenterally for the symptomatic management of psychotic disorders (i.e., schizophrenia).1, 2, 3, 4 Haloperidol decanoate injection is specifically used for the treatment of patients with schizophrenia who require prolonged parenteral antipsychotic therapy.1
Results of short-term studies indicate that oral haloperidol is more effective than placebo and equally or less effective than atypical antipsychotics in the treatment of positive (e.g., delusions, hallucinations) and negative symptoms (e.g., withdrawal from social interaction, blunted emotional expression) of schizophrenia.156, 159, 203, 204
The American Psychiatric Association (APA) recommends that patients with schizophrenia be treated with an antipsychotic medication.201 The APA states that, with the possible exception of clozapine, there currently is no definitive evidence that one antipsychotic agent will have superior efficacy compared with another agent (including first- or second-generation drugs), although meaningful differences in response may be observed in individual patients.201 The choice of an antipsychotic agent should be individualized, considering patient preference, past response to therapy, concurrent medical conditions, and medication-specific factors (e.g., adverse effect profile, available formulations, potential drug interactions, receptor binding profiles, pharmacokinetic considerations).201 Patients whose symptoms improve on an antipsychotic medication should continue treatment with an antipsychotic medication long-term; in most patients, it is appropriate to continue the same antipsychotic medication rather than switch to another antipsychotic medication for maintenance therapy.201 Use of a long-acting injectable antipsychotic is suggested for patients who prefer such treatment or who have a history of poor or uncertain adherence.201
Guidelines from the Department of Veterans Affairs and Department of Defense similarly recommend the use of antipsychotic medication for acute and maintenance treatment of schizophrenia.202 Choice of antipsychotic medication should be based on patient-specific factors and the side effect profiles of the different antipsychotic medications.202 Clozapine should generally be reserved for individuals with treatment-resistant schizophrenia.202 A long-acting injectable antipsychotic may be offered to help improve medication adherence.202
Haloperidol is used orally for the control of tics and vocal utterances of Tourette's syndrome in children and adults.2, 3
A systematic review and network meta-analysis of 39 randomized controlled trials involving a total of 4578 patients compared 23 separate medications, including first-generation antipsychotics, second-generation antipsychotics, and two α-2 agonists (clonidine and guanfacine), for the treatment of tic symptoms in children, adolescents, and adults with Tourette's syndrome.207 All medications included were found to be more effective than placebo at controlling tic symptoms; first- and second-generation antipsychotics were similarly effective, and both antipsychotic classes were more effective than α-2 agonists.207 When comparing individual drugs, aripiprazole, haloperidol, olanzapine, pimozide, risperidone, and clonidine were all more effective than placebo; however, no differences in efficacy were found among the individual antipsychotics.207
The American Academy of Neurology guideline on the treatment of tics in people with Tourette's syndrome states that physicians may prescribe antipsychotics (such as haloperidol) for the treatment of tics when the benefits of treatment outweigh the risks.205 According to the American Academy of Child and Adolescent Psychiatry (AACAP) practice parameter for children and adolescents with tic disorders, including Tourette's disorder, medications should be considered for patients with chronic tic disorders if they have moderate to severe tics causing severe impairment in quality of life or medication-responsive psychiatric comorbidities.206 Atypical antipsychotics such as aripiprazole and risperidone are listed as options to treat tic disorders.206 Haloperidol, pimozide, clonidine, and guanfacine are also listed as having been used for the treatment of tic disorders.206
Antipsychotic agents, mainly haloperidol, have been used in the management of delirium†.208, 209, 210, 211 Haloperidol has been studied as an option for acute treatment of delirium, most commonly for critically ill patients in the intensive care unit (ICU).208, 209 Guidelines published in 2018 by the Society of Critical Care Medicine (SCCM) recommended against routine use of haloperidol to treat delirium in ICU patients, but suggested that it could be considered for short-term use in selected patients experiencing distress (i.e., anxiety, fearfulness, hallucinations, delusions, or agitation).210 Updated guidelines from SCCM published in 2025 were unable to issue a recommendation for or against the use of antipsychotics over usual care for the treatment of delirium in the ICU population.211 In a review of 8 randomized controlled trials involving 1869 patients, antipsychotic use (most commonly haloperidol) resulted in a slight increase in the number of delirium-free days and a possible reduction in 28-day mortality and mortality at longest follow-up; however, other outcomes (e.g., duration of mechanical ventilation, ICU length of stay, hospital length of stay) were not different.211 All of these findings were based on low-certainty evidence.211
Disruptive Behavior Disorder and Attention Deficit Hyperactivity Disorder
Haloperidol is used orally for the treatment of severe behavioral problems in children marked by combativeness and/or explosive hyperexcitable behavior (out of proportion to immediate provocations), and for the short-term treatment of hyperactive children who exhibit excessive motor activity with accompanying conduct disorders that are manifested as impulsive behavior, difficulty sustaining attention, aggression, mood lability, and/or poor frustration tolerance.2, 3 Oral haloperidol should be reserved for use in such patients only after failure of psychotherapy and other, nonantipsychotic medications.2, 3 Overall, evidence supporting use of oral haloperidol for this indication is of low or very low quality.212, 213 Canadian experts recommend against use of haloperidol for treatment of aggression in children and adolescents with conduct disorder due to poor quality evidence and the likelihood for the risks of therapy to outweigh any possible benefits.213
Haloperidol also has been used in the prevention and control of severe nausea and vomiting† (e.g., cancer chemotherapy-induced emesis).214, 263, 296, 297 In current practice, haloperidol is not routinely used for the prophylaxis of chemotherapy-induced nausea and vomiting; instead, it is typically reserved for the treatment of breakthrough nausea and vomiting† in patients who received prophylactic antiemetic therapy with drugs from a different therapeutic class.263, 296, 297 Haloperidol has also been used for the prevention of postoperative nausea and vomiting†, with low doses of 0.5-2 mg found to have similar efficacy to the serotonin (5-HT3) receptor antagonists for this use.214
Dispensing and Administration Precautions
Haloperidol is administered orally, haloperidol lactate is administered orally or by IM injection, and haloperidol decanoate is administered by IM injection.1, 2, 3, 4
Haloperidol lactate has also been administered IV†.5 Haloperidol decanoate injection should not be administered IV.1
Haloperidol decanoate should be administered by deep IM injection into the gluteal region using a 21-gauge needle, usually at monthly intervals.1 The maximum volume of haloperidol decanoate should not exceed 3 mL per IM injection site.1
Haloperidol lactate injection should be administered at intervals based on patient response; the injection may be administered as often as every hour, although 4- to 8-hour intervals may be satisfactory.4
Haloperidol lactate and decanoate injections should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.1, 4 Administration of IM haloperidol decanoate or lactate in pediatric patients is not recommended.1, 4
Store haloperidol decanoate injection at controlled room temperature (15—30°C); do not refrigerate or freeze, and protect from light.1
Store haloperidol tablets at controlled room temperature (20—25°C); protect from light.2 Dispense in a tight, light-resistant container.2
Store haloperidol lactate oral solution and injection at controlled room temperature (20—25°C); do not freeze, and protect from light.3, 4 Dispense oral solution in a tight, light-resistant container.3
Dosage of haloperidol lactate and the decanoate is expressed in terms of haloperidol.1, 3, 4
There is considerable interindividual variation in optimal dosage requirements of haloperidol, and dosage must be carefully adjusted according to individual requirements and response, using the lowest possible effective dosage.2, 3, 4 To determine the initial dosage, consideration should be given to the patient's age, severity of illness, previous response to other antipsychotic drugs, and concomitant medication(s) or disease state(s).2, 3, 4 Children, debilitated or geriatric patients, and patients with a history of adverse reactions to antipsychotic drugs may require less haloperidol.2, 3, 4 In such patients, the optimal response is usually obtained with more gradual dosage adjustments and at lower dosage levels.2, 3, 4
IM Dosage (Haloperidol Decanoate)
For patients with schizophrenia requiring prolonged antipsychotic therapy (e.g., patients with chronic schizophrenic disorder), the long-acting haloperidol decanoate injection may be considered.1 The patient's condition should initially be stabilized with an antipsychotic agent prior to attempting conversion to haloperidol decanoate.1 In addition, if the patient is receiving an antipsychotic agent other than haloperidol, it is recommended that the patient initially be converted to oral haloperidol therapy in order to minimize the risk of an unexpected adverse reaction to the drug.1
Initial therapy : The initial IM dose of haloperidol decanoate should be based on the patient's clinical history, physical condition, and response to previous antipsychotic therapy.1 To determine the minimum effective dosage, haloperidol decanoate therapy has been initiated at low initial doses and gradually titrated upward as necessary.1 For patients previously maintained on low doses of antipsychotics (e.g., up to the equivalent of 10 mg/day oral haloperidol), an initial dose 10-15 times the previous daily dose of oral haloperidol equivalents is recommended, although limited clinical experience suggests that a lower initial dosage of the decanoate may be adequate.1
Conversion from oral haloperidol to haloperidol decanoate can be achieved by using an initial dose of haloperidol decanoate that is 10-20 times the previous daily dose in oral haloperidol equivalents.1 Lower initial IM dosages (i.e., 10-15 times the previous daily dose of oral haloperidol) are recommended for patients who are geriatric, debilitated, or stabilized on low oral dosages (e.g., up to the equivalent of 10 mg daily of oral haloperidol).1 Higher initial IM dosages (i.e., 20 times the previous daily dosage of oral haloperidol) should be considered for patients who are stabilized on high oral dosages of antipsychotic agents, those who are at risk of relapse, and those who are tolerant to oral haloperidol, with downward titration on succeeding injections.1
The initial dosage of haloperidol decanoate should not exceed 100 mg regardless of previous antipsychotic dosage requirements.1 If conversion requires an initial dosage of haloperidol decanoate higher than 100 mg daily, such dosage should be administered in 2 injections (i.e., administering a maximum initial dose of 100 mg followed by the balance in 3-7 days).1
Maintenance therapy : The maintenance dosage of haloperidol decanoate must be individualized with upward or downward dosage titration based on clinical response.1 The usual adult maintenance IM dosage is 10-15 times the previous daily dosage of oral haloperidol for adult patients depending on the clinical response of the patient.1
Haloperidol decanoate usually has been administered IM at monthly intervals (i.e., every 4 weeks), but individual response may dictate the need for adjusting the dosing interval as well as the dosage.1
Close clinical observation is required during dosage titration in order to minimize the risk of overdosage and of emergence of psychotic manifestations prior to the next dose.1 If supplemental antipsychotic therapy is necessary during periods of dosage titration or for control of acute exacerbations of psychotic manifestations, a short-acting haloperidol preparation should be used.1 Experience with haloperidol decanoate dosages exceeding 450 mg (of haloperidol) monthly is limited.1
IM Dosage (Haloperidol Lactate)
For the prompt control of acutely agitated schizophrenic patients with moderately severe to very severe symptoms, the usual initial adult IM dose of haloperidol lactate is 2-5 mg (of haloperidol) given as a single dose.4 Depending on the response of the patient, this dose may be repeated as often as every hour; however, IM administration of haloperidol lactate every 4-8 hours may be adequate to control symptoms in some patients.4 The maximum dosage is 20 mg/day.4
Oral therapy should replace short-acting parenteral therapy as soon as possible.4 Depending on the patient's clinical status, the first oral dose should be given within 12-24 hours following administration of the last parenteral dose of haloperidol lactate.4
Since bioavailability studies to establish bioequivalence between oral and parenteral dosage forms of haloperidol have not been conducted to date, the manufacturers suggest that the parenteral dosage administered during the preceding 24 hours be used for initial approximation of the total daily oral dosage required.4 Since this dosage is only an initial estimate, patients being switched from parenteral haloperidol lactate therapy to oral therapy should be closely monitored, particularly for clinical signs and symptoms of efficacy, sedation, and adverse effects, for the first several days following initiation of oral therapy.4 Subsequent dosage may be increased or decreased according to the patient's tolerance and therapeutic response, using the lowest possible effective dosage.4
Oral Dosage
For the symptomatic management of psychotic disorders in adults with moderate symptomatology and in geriatric or debilitated patients, the manufacturers state that the usual initial oral dosage of haloperidol is 0.5-2 mg administered 2 or 3 times daily.2, 3 To achieve prompt control, higher initial dosages may be required in some patients.2, 3 Subsequent dosage should be carefully adjusted according to the patient's tolerance and therapeutic response.2, 3 Dosage during prolonged maintenance therapy should be kept at the lowest effective level.2, 3
For the symptomatic management of psychotic disorders in adults with severe symptomatology and/or chronic or resistant disorders, the manufacturers state that the usual initial oral dosage of haloperidol is 3-5 mg administered 2 or 3 times daily.2, 3 To achieve prompt control, higher initial dosages may be required in some patients.2, 3 Subsequent dosage should be carefully adjusted according to the patient's tolerance and therapeutic response.2, 3 Dosage during prolonged maintenance therapy should be kept at the lowest effective level.2, 3
Patients who remain severely disturbed or inadequately controlled despite receiving recommended dosages of haloperidol may require dosage adjustment.2, 3 Oral haloperidol dosages up to 100 mg daily may be necessary in some cases to achieve an optimal response.2, 3 The manufacturers state that haloperidol has been used infrequently in dosages exceeding 100 mg daily in severely resistant disorders in adults, but that the limited use has not demonstrated the safety of prolonged administration of such high dosages of the drug.2, 3
Oral therapy should replace short-acting parenteral therapy as soon as possible.2, 3 Depending on the patient's clinical status, the first oral dose should be given within 12-24 hours following administration of the last parenteral dose.2, 3 Since bioavailability studies to establish bioequivalence between oral and parenteral dosage forms of haloperidol have not been conducted to date, the manufacturers suggest that the parenteral dosage administered during the preceding 24 hours be used for initial approximation of the total daily oral dosage required.2, 3 Since this dosage is only an initial estimate, patients being switched from parenteral haloperidol therapy to oral therapy should be closely monitored, particularly for clinical signs and symptoms of efficacy, sedation, and adverse effects, for the first several days following initiation of oral therapy.2, 3 Subsequent dosage may be increased or decreased according to the patient's tolerance and therapeutic response, using the lowest possible effective dosage.2, 3
Oral Dosage
For the symptomatic management of Tourette's disorder in adults with moderate symptomatology and in geriatric or debilitated patients, the manufacturers state that the usual initial oral dosage of haloperidol is 0.5-2 mg administered 2 or 3 times daily.2, 3 To achieve prompt control, higher initial dosages may be required in some patients.2, 3 Subsequent dosage should be carefully adjusted according to the patient's tolerance and therapeutic response.2, 3 Dosage during prolonged maintenance therapy should be kept at the lowest effective level.2, 3
For the symptomatic management of Tourette's disorder in adults with severe symptomatology and/or chronic or resistant disorders, the manufacturers state that the usual initial oral dosage of haloperidol is 3-5 mg administered 2 or 3 times daily.2, 3 To achieve prompt control, higher initial dosages may be required in some patients.2, 3 Subsequent dosage should be carefully adjusted according to the patient's tolerance and therapeutic response.2, 3 Dosage during prolonged maintenance therapy should be kept at the lowest effective level.2, 3
Patients who remain severely disturbed or inadequately controlled despite receiving recommended dosages of haloperidol may require dosage adjustment.2, 3 Oral haloperidol dosages up to 100 mg daily may be necessary in some cases to achieve an optimal response.2, 3 In addition, these manufacturers further state that haloperidol has been used infrequently in dosages exceeding 100 mg daily in severely resistant disorders in adults, but that the limited use has not demonstrated the safety of prolonged administration of such high dosages of the drug.2, 3
Oral Dosage
For the symptomatic management of psychotic disorders in children 3-12 years of age and weighing 15-40 kg, the usual dosage range is 0.05-0.15 mg/kg daily given in 2 or 3 divided doses; however, severely disturbed psychotic children may require higher dosages.2, 3 Therapy should begin at the lowest dose possible (0.5 mg daily).2, 3 Subsequent dosage may be increased by 0.5 mg daily at 5- to 7-day intervals, depending on the patient's tolerance and therapeutic response.2, 3 Dosage during prolonged maintenance therapy should be kept at the lowest possible effective level; once an adequate response has been achieved, dosage should be gradually reduced and subsequently adjusted according to the patient's therapeutic response and tolerance.2, 3
Oral Dosage
For the management of nonpsychotic behavioral problems in children 3-12 years of age and weighing 15-40 kg, the usual dosage range is 0.05-0.075 mg/kg daily given in 2 or 3 divided doses.2, 3 Therapy should begin at the lowest dose possible (0.5 mg daily).2, 3 Subsequent dosage may be increased by 0.5 mg daily at 5- to 7-day intervals, depending on the patient's tolerance and therapeutic response.2, 3 Once an adequate response has been achieved, dosage should be gradually reduced and subsequently adjusted according to the patient's therapeutic response and tolerance.2, 3
Disruptive Behavior Disorder and Attention Deficit Hyperactivity Disorder
Oral Dosage
For the control of disruptive behavior disorder and attention deficit hyperactivity disorder in children 3-12 years of age and weighing 15-40 kg, the usual dosage range is 0.05-0.075 mg/kg daily given in 2 or 3 divided doses.2, 3 Therapy should begin at the lowest dose possible (0.5 mg daily).2, 3 Subsequent dosage may be increased by 0.5 mg daily at 5- to 7-day intervals, depending on the patient's tolerance and therapeutic response.2, 3 Once an adequate response has been achieved, dosage should be gradually reduced and subsequently adjusted according to the patient's therapeutic response and tolerance.2, 3
Unlike psychotic disorders for which prolonged therapy is usually required, nonpsychotic or hyperactive behavioral problems in children may be acute, and short-term administration of haloperidol may be adequate.2, 3 A maximum effective dosage of haloperidol for the management of behavioral problems in children has not been established; however, the manufacturers state that there is little evidence that improvement in behavior is further enhanced at dosages greater than 6 mg daily.2, 3
The manufacturers make no specific dosage recommendations for patients with hepatic impairment.1, 2, 3, 4 Studies of IM haloperidol in patients with hepatic impairment have not been conducted.1, 4
The manufacturers make no specific dosage recommendations for patients with renal impairment.1, 2, 3, 4
Geriatric patients may require less haloperidol; in such patients, the optimal response is usually obtained with more gradual dosage adjustments and at lower dosage levels as recommended above.1, 2, 3, 4
Increased Mortality in Geriatric Patients with Dementia-related Psychosis
A boxed warning about an increased risk of mortality in geriatric patients with dementia-related psychosis treated with antipsychotic agents is included in the prescribing information for haloperidol.1, 2, 3, 4 Analyses of 17 placebo-controlled trials (modal duration of 10 weeks) in geriatric patients mainly receiving atypical antipsychotic agents revealed an approximate 1.6- to 1.7-fold increase in mortality compared with that in patients receiving placebo.1, 2, 3, 4 Over the course of a typical 10-week controlled trial, the rate of death in drug-treated patients was about 4.5% compared with a rate of about 2.6% in those receiving placebo.1, 2, 3, 4 Although the causes of death were varied in these trials, most of the deaths appeared to be either cardiovascular (e.g., heart failure, sudden death) or infectious (e.g., pneumonia) in nature.1, 2, 3, 4 Observational studies suggest that, similar to atypical antipsychotic agents, treatment with conventional antipsychotic agents may increase mortality.1, 2, 3, 4 However, the extent to which these findings of increased mortality in observational studies may be attributed to the antipsychotic agent as opposed to certain patient characteristics remains unclear.1, 2, 3, 4 Haloperidol is not approved for the treatment of dementia-related psychosis.1, 2, 3, 4
Other Warnings and Precautions
Cases of sudden death, QTc-interval prolongation, and torsades de pointes have been reported in patients receiving haloperidol.1, 2, 3, 4 Use of higher than recommended doses of any haloperidol formulation appears to be associated with an increased risk of QTc-interval prolongation and torsades de pointes.1, 2, 4 Also, a QTc interval that exceeds 500 msec is associated with an increased risk of torsades de pointes.1, 4 Although these effects have been reported in the absence of predisposing factors, haloperidol should be used with particular caution in patients with other conditions that prolong the QTc interval, including electrolyte imbalance (particularly hypokalemia and hypomagnesemia), underlying cardiac abnormalities, hypothyroidism, and familial long QT syndrome, as well as in those concurrently receiving other drugs known to prolong the QTc interval.1, 2, 4
ECG monitoring for QTc monitoring and arrhythmias is recommended if haloperidol lactate is administered IV†.4 Haloperidol decanoate must not be administered IV.1
Tachycardia and hypotension (including orthostatic hypotension) have also been reported occasionally in patients.1, 4
Cerebrovascular Adverse Reactions
Adverse cerebrovascular events (e.g., stroke, transient ischemic attack), some of which resulted in fatalities, have been reported in controlled studies in geriatric patients with dementia-related psychosis treated with antipsychotics.1, 4 The mechanism for this increased risk is unknown.1, 4
Haloperidol should be used with caution in patients with risk factors for adverse cerebrovascular reactions.1, 4
Use of antipsychotic agents may be associated with tardive dyskinesia, a syndrome of potentially irreversible, involuntary, dyskinetic movements.1, 2, 3, 4 The risk of developing tardive dyskinesia appears to be greater in geriatric patients receiving high dosages of the drug, especially females.1, 2, 3, 4
Although not clearly established, the risk of developing the syndrome and the likelihood that it will become irreversible may increase with the duration of therapy and total cumulative dose of antipsychotic agent(s) administered; however, the syndrome may occur, although much less frequently, after relatively short periods of treatment with low dosages.1, 2, 3, 4
Tardive dyskinesia may remit, partially or completely, if antipsychotic therapy is discontinued.1, 2, 3, 4 However, antipsychotic therapy itself may suppress or partially suppress the signs and symptoms of the syndrome and thereby may possibly mask the underlying process.1, 2, 3, 4 The effect that such symptomatic suppression has upon the long-term course of tardive dyskinesia is unknown.1, 2, 3, 4
Haloperidol should be prescribed in a manner that is most likely to minimize the occurrence of tardive dyskinesia.1, 2, 3, 4 Chronic antipsychotic treatment generally should be reserved for patients who suffer from a chronic illness that is known to respond to antipsychotic agents, and for whom alternative, equally effective, but potentially less harmful treatments are not available or appropriate.1, 2, 3, 4 In patients who do require chronic treatment, the lowest dosage and the shortest duration of treatment producing a satisfactory clinical response should be sought, and the need for continued treatment should be reassessed periodically.1, 2, 3, 4
If signs and symptoms of tardive dyskinesia appear in a haloperidol-treated patient, drug discontinuance should be considered; however, some patients may require continued treatment with the drug despite the presence of the syndrome.1, 2, 3, 4
Neuroleptic Malignant Syndrome
Neuroleptic malignant syndrome (NMS) may occur in patients receiving haloperidol or other antipsychotic therapy.1, 2, 3, 4 NMS is potentially fatal and requires immediate discontinuance of the drug and initiation of intensive symptomatic and supportive care.1, 2, 3, 4
If a patient requires antipsychotic therapy following recovery from NMS, the potential reintroduction of drug therapy should be carefully considered.1, 2, 3, 4 The patient should be carefully monitored since recurrences of NMS have been reported.1, 2, 3, 4
Neurologic Adverse Reactions in Patients with Parkinson's Disease or Dementia with Lewy Bodies
Patients with Parkinson's disease or dementia with Lewy bodies are reported to have an increased sensitivity to antipsychotic agents.1, 4 Increased sensitivity with haloperidol treatment may manifest as severe extrapyramidal symptoms, confusion, sedation, and falls.1, 4 In addition, haloperidol may impair the antiparkinson effects of levodopa and other dopamine agonists.1, 4
Haloperidol is contraindicated in patients with Parkinson's disease; in addition, IM haloperidol is contraindicated in patients with dementia with Lewy bodies.1, 2, 3, 4
Concomitant Therapy with Lithium
A few patients receiving lithium and haloperidol concurrently have experienced an acute encephalopathic syndrome (characterized by weakness, lethargy, fever, tremulousness and confusion, extrapyramidal symptoms, leukocytosis, as well as elevated serum enzymes, blood urea nitrogen, and fasting blood sugar) followed by irreversible brain damage.1, 2, 3, 4 A causal relationship between these events and the concomitant administration of lithium and haloperidol has not been established.1, 2, 3, 4
Patients receiving such combined therapy should be observed for evidence of adverse neurologic effects; treatment should be promptly discontinued if such signs or symptoms appear.1, 2, 3, 4
Laryngospasm, bronchospasm, and increased depth of respiration have occurred in patients receiving haloperidol.1, 2, 3, 4 Bronchopneumonia, resulting in fatalities in some patients, has occurred following the use of antipsychotic agents, including haloperidol.1, 2, 3, 4 It has been suggested that lethargy and decreased thirst, resulting from central inhibition, may cause dehydration, hemoconcentration, and reduced pulmonary ventilation.1, 2, 3, 4
If the above signs and symptoms appear, especially in geriatric patients, remedial therapy should be initiated promptly.1, 2, 3, 4
Ocular changes have been reported in patients receiving chemically-related drugs, although not reported with haloperidol.1, 2, 3, 4
There have been postmarketing reports of hypersensitivity reactions with haloperidol, including anaphylactic reactions, angioedema, exfoliative dermatitis, hypersensitivity vasculitis, rash, urticaria, face edema, laryngeal edema, bronchospasm, and laryngospasm.1, 4
Haloperidol is contraindicated in patients with hypersensitivity to the drug.1, 2, 3, 4
Haloperidol may cause somnolence, postural hypotension, and motor and sensory instability, which could lead to falls and, consequently, fractures or other injuries.1, 2, 3, 4
Complete fall risk assessments when initiating haloperidol and during long-term antipsychotic therapy in patients with concomitant diseases, conditions, or medications that could exacerbate the risk of falls.1, 2, 3, 4
Because of the possibility of transient hypotension and/or precipitation of angina, haloperidol should be used with caution in patients with severe cardiovascular disorders.1, 2, 3, 4 If hypotension occurs, metaraminol, norepinephrine, or phenylephrine may be used; epinephrine should not be used since haloperidol causes a reversal of epinephrine's vasopressor effects and a further lowering of blood pressure.1, 2, 3, 4
Since haloperidol may lower the seizure threshold, the drug should be used with caution in patients receiving anticonvulsant agents and in those with a history of seizures or EEG abnormalities.1, 2, 3, 4 Adequate anticonvulsant therapy should be maintained during administration of haloperidol.1, 2, 3, 4
Patients should be warned that haloperidol may impair their ability to perform activities requiring mental alertness or physical coordination (e.g., operating machinery, driving a motor vehicle).1, 2, 3, 4 Patients also should be warned that haloperidol may enhance their response to alcohol or other CNS depressants.1, 2, 3, 4
Extrapyramidal reactions occur frequently with haloperidol, especially during the first few days of therapy.2, 3 In most patients, these reactions consist of parkinsonian symptoms, akathisia, or dystonia.2, 3 While these symptoms can occur at relatively low dosages, they occur more frequently and with greater severity at higher dosages.2, 3
The symptoms may be controlled with dosage reductions or administration of an anticholinergic antiparkinsonian drug (e.g., benztropine, trihexyphenidyl).2, 3 If persistent extrapyramidal reactions occur, haloperidol therapy may have to be discontinued.2, 3
Haloperidol should be used with caution in patients with thyrotoxicosis since severe neurotoxicity (e.g., rigidity, inability to walk or talk) may occur in these patients during therapy with an antipsychotic agent.1, 2, 3, 4
The manufacturers caution that when haloperidol is used to control mania in patients with bipolar disorder, there may be a rapid mood swing to depression.1, 2, 3, 4
In general, abrupt withdrawal of antipsychotic agents following short-term administration is not associated with adverse effects; however, transient dyskinetic signs have occurred following abrupt withdrawal in patients receiving prolonged maintenance therapy with haloperidol.2, 3, 4 In some patients, the dyskinetic movements are indistinguishable, except on the basis of their duration, from tardive dyskinesia.2, 3, 4 It is not known whether gradual withdrawal of antipsychotic agents reduces the incidence of withdrawal-emergent neurologic signs; however, if haloperidol therapy must be discontinued, gradual withdrawal of the drug is recommended, if possible, pending further accumulation of data.2, 3, 4
Antipsychotic agents increase serum prolactin concentrations; the elevation persists during chronic administration.1, 2, 3, 4 Although disturbances such as galactorrhea, amenorrhea, gynecomastia, and impotence have been reported, further study is needed to determine the clinical importance in most patients of elevated serum prolactin concentrations associated with antipsychotic agents.1, 2, 3, 4
An increase in mammary neoplasms has been found in rodents following long-term administration of antipsychotic agents.1, 2, 3, 4
Since in vitro tests indicate that approximately one-third of human breast cancers are prolactin dependent, haloperidol should be used with caution in patients with previously detected breast cancer.1, 2, 3, 4
Although not reported to date with haloperidol, the manufacturers caution that decreases in serum cholesterol concentration have occurred in patients receiving chemically-related drugs.1, 2, 3, 4
Cases of leukopenia and neutropenia have been reported in patients receiving antipsychotic agents, including haloperidol; agranulocytosis (including fatal cases) has also been reported.1, 2, 3, 4
Patients with a preexisting low leukocyte count or a history of drug-induced leukopenia or neutropenia should have their complete blood count monitored frequently during the first few months of therapy, and haloperidol should be discontinued at the first sign of a decline in the leukocyte count in the absence of other causative factors.1, 2, 3, 4
Haloperidol-treated patients with neutropenia should be carefully monitored for fever or other signs or symptoms of infection and be treated promptly should such signs and symptoms occur.1, 2, 3, 4 Patients with severe neutropenia (absolute neutrophil count less than 1000/mm3) should discontinue haloperidol and have their leukocyte count followed until recovery.1, 2, 3, 4
Although there are no adequate and controlled studies to date in humans, cases of limb malformations have occurred in offspring of women who were given haloperidol concurrently with other potentially teratogenic drugs during the first trimester of pregnancy; these teratogenic effects have not been directly attributed to haloperidol.1, 2, 3, 4 Haloperidol has been shown to be teratogenic and fetotoxic in animals administered oral or parenteral haloperidol.1, 2, 3, 4
Neonates exposed to antipsychotic agents, including haloperidol, during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery.1, 2, 3, 4 Symptoms reported in these neonates to date include agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, and feeding disorder.1, 2, 3, 4 Symptoms were self-limiting in some neonates, but varied in severity; some infants required intensive care unit support and prolonged hospitalization.1, 2, 3, 4
Haloperidol should be used during pregnancy or in women likely to become pregnant only when the potential benefits justify the possible risks to the fetus.1, 2, 3, 4
Haloperidol is distributed into human milk.1, 4 The manufacturers warn that nursing should not be undertaken by women receiving haloperidol.1, 2, 3, 4
Safety and efficacy of IM haloperidol decanoate or lactate injection in children have not been established; safety and efficacy of oral haloperidol preparations in children younger than 3 years of age have not been established.1, 2, 3, 4
Clinical studies of haloperidol did not include sufficient numbers of geriatric patients 65 years of age and older to determine whether this age group responds differently from younger adults.1, 2, 3, 4 Other reported clinical experience has not consistently identified differences in responses between geriatric and younger patients.1, 2, 3, 4 However, the prevalence of tardive dyskinesia appears to be highest among geriatric patients, particularly elderly women.1, 2, 3, 4 In addition, the pharmacokinetics of haloperidol generally warrant the use of reduced dosages in geriatric patients.1, 2, 3, 4
Geriatric patients with dementia-related psychosis treated with antipsychotic agents are at an increased risk of death.1, 2, 3, 4
Studies of IM haloperidol in patients with hepatic impairment have not been conducted.1, 4 Haloperidol concentrations may be increased in hepatically impaired patients, since the drug is primarily metabolized by the liver and protein binding may decrease.1, 4
The manufacturers make no specific dosage recommendations for patients with renal impairment.1, 2, 3, 4
The most frequent adverse effects of haloperidol involve the CNS and include extrapyramidal reactions (e.g., Parkinson-like symptoms, akathisia, dystonia).1, 2, 3, 4
Based on the pooled safety data, the most common adverse effects in patients treated with IM haloperidol lactate (≥5%) were extrapyramidal disorder, hyperkinesia, tremor, hypertonia, dystonia, and somnolence.4
The most common adverse reactions (≥5%) in haloperidol decanoate-treated patients in a double-blind, active comparator-controlled clinical trial were parkinsonism and oculogyric crisis.1
Haloperidol is metabolized by cytochrome P-450 (CYP) isoenzymes, mainly CYP3A4 and, to a lesser extent, CYP2D6.1, 4 Haloperidol is an inhibitor of CYP2D6.1
Drugs Affecting or Metabolized by Hepatic Microsomal Enzymes
CYP3A4 Inhibitors
CYP3A4 inhibitors (e.g., alprazolam, itraconazole, ketoconazole, nefazodone, ritonavir) may increase the plasma concentrations of haloperidol if used concomitantly.1, 4 The effect of CYP3A4 inhibition and of decreased CYP2D6 enzyme activity may be additive.1, 4
Increased haloperidol plasma concentrations may increase the risk of adverse events, including QTc interval prolongation.1, 4 Increases in QTc were observed when haloperidol was administered concomitantly with ketoconazole (400 mg/day).1, 3, 4
If used concomitantly, monitor for signs or symptoms of increased or prolonged pharmacologic effects of haloperidol, and decrease the haloperidol dosage as needed.1, 4
CYP2D6 Inhibitors
CYP2D6 inhibitors (e.g., chlorpromazine, promethazine, quinidine, paroxetine, sertraline, venlafaxine) may increase the plasma concentrations of haloperidol if used concomitantly.1, 4 The effect of CYP3A4 inhibition and of decreased CYP2D6 enzyme activity may be additive. 1, 4
Increased haloperidol plasma concentrations may increase the risk of adverse events, including QTc interval prolongation.1, 4 Increases in QTc were observed when haloperidol was administered concomitantly with paroxetine (20 mg/day).1, 4
If used concomitantly, monitor for signs or symptoms of increased or prolonged pharmacologic effects of haloperidol, and decrease the haloperidol dosage as needed.1, 4
Combined CYP3A4 and CYP2D6 inhibitors
Combined CYP3A4 and CYP2D6 inhibitors (e.g., fluoxetine, fluvoxamine, ritonavir) may increase the plasma concentrations of haloperidol if used concomitantly.1, 4
If used concomitantly, monitor for signs or symptoms of increased or prolonged pharmacologic effects of haloperidol, and decrease the haloperidol dosage as needed.1, 4
CYP3A4 Inducers
Potent CYP3A4 inducers (e.g., carbamazepine, phenobarbital, phenytoin, rifampin, St John's Wort) may decrease the plasma concentrations of haloperidol if used concomitantly, thereby reducing haloperidol efficacy.1, 4
Concomitant oral therapy with rifampin and haloperidol in schizophrenic patients resulted in a mean 70% decrease in plasma haloperidol concentrations and decreased antipsychotic efficacy.1, 2, 4 Following discontinuance of rifampin in other schizophrenic patients treated with oral haloperidol, mean haloperidol concentrations increased 3.3-fold.1, 2, 4
In patients with schizophrenia receiving concomitant haloperidol and increasing doses of carbamazepine, haloperidol plasma concentrations decreased linearly with increasing carbamazepine concentrations.1, 4
If used concomitantly, monitor patients and increase the dosage of haloperidol or adjust the dosage interval as needed.1, 4 After withdrawal of the CYP3A4 inducer, haloperidol concentrations may gradually increase and therefore it may be necessary to reduce the dosage of haloperidol or adjust the dosage interval.1, 4
CYP2D6 Substrates
Plasma concentrations of CYP2D6 substrates (e.g., tricyclic antidepressants such as desipramine or imipramine) may increase when used concomitantly with haloperidol.1, 4
Drugs that Prolong QT Interval
Cases of QTc-interval prolongation and torsades de pointes have been reported in patients receiving haloperidol.1, 2, 3, 4
Particular caution is advised when haloperidol is used in patients with QT prolongation or in patients concurrently receiving other drugs that prolong the QTc interval, including class 1A antiarrhythmics (e.g., procainamide, quinidine, disopyramide), class 3 antiarrhythmics (e.g., amiodarone, sotalol), and other drugs such as citalopram, erythromycin, levofloxacin, methadone, and ziprasidone.1, 4
Drugs Known to Cause Electrolyte Imbalances
Use caution when haloperidol is used in combination with drugs known to cause electrolyte imbalance (e.g., diuretics, corticosteroids) because hypokalemia, hypomagnesemia, and hypocalcemia are risk factors for QTc prolongation.1, 4
The manufacturers caution that increases in intraocular pressure may occur in patients receiving anticholinergic drugs, including antiparkinsonian agents, concurrently with haloperidol.1, 2, 3, 4
Haloperidol was reported to antagonize the anticoagulant activity of an anticoagulant (phenindione, no longer commercially available in the US) in one patient.1, 2, 3, 4 Use haloperidol with caution in patients receiving anticoagulants.1, 2, 3, 4
Haloperidol may be additive with, or may potentiate the action of, other CNS depressants such as opiates, anesthetics, or alcohol.1, 2, 3, 4
Haloperidol may impair the antiparkinson effects of levodopa and other dopamine agonists.1, 4 If concomitant therapy with haloperidol and an antiparkinson medication is required, it may have to be continued after haloperidol is discontinued because of the difference in excretion rates.2, 3, 4 If both are discontinued simultaneously, extrapyramidal symptoms may occur.2, 3, 4 Increases in intraocular pressure also may occur with concomitant use.1, 2, 3, 4
Buspirone may increase the plasma concentrations of haloperidol if used concomitantly.1, 4
If used concomitantly, monitor for signs or symptoms of increased or prolonged pharmacologic effects of haloperidol, and decrease the haloperidol dosage as needed.1, 4
A few patients receiving lithium and haloperidol concurrently have experienced an acute encephalopathic syndrome.1, 2, 3, 4 A causal relationship between these events and the concomitant administration of lithium and haloperidol has not been established.1, 2, 3, 4
Patients receiving such combined therapy should be observed for evidence of adverse neurologic effects; treatment should be promptly discontinued if such signs or symptoms appear.1, 2, 3, 4
Sodium valproate, which inhibits glucuronidation, does not affect haloperidol plasma concentrations.1, 4
Haloperidol is the first of the butyrophenone series of major antipsychotics/tranquilizers.2, 3, 4 Haloperidol is commercially available as the base, decanoic acid ester (decanoate), and lactate salt.1, 2, 3, 4 Haloperidol decanoate, the decanoate ester of haloperidol, has a markedly extended duration of effect.1 Haloperidol decanoate injection is commercially available as a sterile solution of the drug in sesame oil.1
Haloperidol is considered a conventional (prototypical, first-generation) antipsychotic agent.5 The precise mechanism of antipsychotic action of haloperidol is unclear.1, 2, 3, 4 However, the efficacy of haloperidol could be mediated through its activity as an antagonist at central dopamine type 2 receptors.1, 4 The drug also binds to alpha-1 adrenergic receptors, but with lower affinity.1, 4 Haloperidol displays minimal binding to muscarinic, cholinergic, and histaminergic (H1) receptors.1, 4
Haloperidol undergoes extensive metabolism, leading to substantial interindividual variability in its pharmacokinetics.5 Oral bioavailability of the drug has been reported to range from 60-70%.5 Peak plasma concentrations of haloperidol occur within 2-6 hours following oral administration, and 20 minutes following IM administration of haloperidol lactate.5
Administration of haloperidol decanoate in sesame oil leads to slow and sustained release of haloperidol.1 Plasma concentrations of haloperidol increase gradually, peaking at about 6 days post injection, and decreasing thereafter.1 Steady state plasma concentrations are achieved within 2-4 months in patients receiving monthly injections.1 For doses below 450 mg, the relationship between the dose of haloperidol decanoate and plasma haloperidol concentration is approximately linear.1 However, there is considerable variation between individuals in the pharmacokinetics of haloperidol decanoate following IM administration.1
Haloperidol is approximately 89-93% bound to plasma proteins.5 Haloperidol is metabolized by several routes, with glucuronidation and ketone reduction being the major pathways.1, 4 The cytochrome P-450 (CYP) system is also involved, mainly CYP3A4 and, to a lesser extent, CYP2D6.1, 4 Haloperidol is primarily excreted in the urine (approximately 30%).5 Following IM administration of haloperidol decanoate, the drug has an apparent elimination half-life of approximately 3 weeks.1
Additional Information
The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer's labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
Oral | Tablets | 0.5 mg* | Haloperidol Tablets | |
1 mg* | Haloperidol Tablets | |||
2 mg* | Haloperidol Tablets | |||
5 mg* | Haloperidol Tablets | |||
10 mg* | Haloperidol Tablets | |||
20 mg* | Haloperidol Tablets |
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
Parenteral | Injection, for IM use only | 50 mg (of haloperidol) per mL* | Haldol® Decanoate | Ortho-McNeil-Janssen |
Haloperidol Decanoate Injection | ||||
100 mg (of haloperidol) per mL* | Haldol® Decanoate | Ortho-McNeil-Janssen | ||
Haloperidol Decanoate Injection |
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
Oral | Solution | 2 mg (of haloperidol) per mL* | Haloperidol Lactate Oral Solution Concentrate | |
Parenteral | Injection | 5 mg (of haloperidol) per mL* | Haloperidol Lactate Injection |
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Only references cited for selected revisions after 1984 are available electronically.
1. Janssen Pharmaceuticals, Inc. Haldol® (haloperidol decanoate) injection prescribing information. Titusville, NJ; 2025 Jan.
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3. Advagen Pharma Ltd. Haloperidol oral solution (concentrate) prescribing information. East Windsor, NJ; 2024 Feb.
4. Mylan Institutional LLC. Haloperidol lactate injection prescribing information. Morgantown, WV; 2024 Nov.
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