Reviewed on 6/23/2023

What Is Iloperidone and How Does It Work?

Iloperidone is a prescription medication used for the treatment of schizophrenia.

  • Iloperidone is available under the following different brand names: Fanapt

What Are Side Effects Associated with Using Iloperidone?

Common side effects of Iloperidone include:

Serious side effects of Iloperidone include:

  • drooling
  • trouble swallowing
  • signs of infection (such as persistent cough, fever)
  • shaking (tremors)
  • muscle spasms

Rare side effects of Iloperidone include:

  • none

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Are Dosages of Iloperidone?

Adult dosage


  • 1 mg
  • 2 mg
  • 4 mg
  • 6 mg
  • 8 mg
  • 10 mg
  • 12 mg


Adult dosage

  • Day 1: 1 mg orally every 12 hr; increase every day to the effective dose of 6-12 mg orally every 12 hr
  • Day 2: 2 mg orally every 12 hr, then increase every day by 2 mg/day to the effective dose of 6-12 mg orally every 12 hr; not to exceed 24 mg/day
  • Must gradually increase the dose to avoid orthostatic hypotension

Dosage Considerations – Should be Given as Follows:

  • See “Dosages”

What Other Drugs Interact with Iloperidone?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, healthcare provider, or pharmacist first.

  • Iloperidone has severe interactions with the following drugs:
    • amisulpride
    • flibanserin
    • goserelin
    • leuprolide
    • lonafarnib
  • Iloperidone has serious interactions with at least 135 other drugs
  • Iloperidone has moderate interactions with at least 548 other drugs
  • Iloperidone has minor interactions with the following drugs:
    • azithromycin
    • brimonidine
    • chasteberry
    • chloroquine
    • duloxetine
    • eslicarbazepine acetate
    • estradiol vaginal
    • ethanol
    • eucalyptus
    • irinotecan
    • irinotecan liposomal
    • pazopanib
    • sage

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Iloperidone?


Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Iloperidone?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Iloperidone?”


  • Prolongs QT interval; exercise caution with other drugs/conditions that increase QTc
  • Not recommended for patients with hepatic impairment
  • May cause anticholinergic side effects (eg, confusion, agitation)
  • Three cases of priapism were reported in the premarketing program; drugs with alpha-adrenergic blocking effects have been reported to induce priapism; Iloperidone shares this pharmacologic activity; severe priapism may require surgical intervention
  • Should be avoided in patients with a known genetic susceptibility to congenital long QT syndrome and with a history of cardiac arrhythmias
  • May cause somnolence, postural hypotension, motor and sensory instability, which may lead to falls and, consequently, fractures or other injuries; for patients with diseases, conditions, or medications that could exacerbate these effects, complete fall risk assessments when initiating antipsychotic treatment and recurrently for patients on long-term antipsychotic therapy
  • Can induce orthostatic hypotension associated with dizziness, tachycardia, and syncope; use with caution in patients with known cardiovascular disease (eg, heart failure, history of myocardial infarction, ischemia, or conduction abnormalities), cerebrovascular disease, or conditions that predispose the patient to hypotension (dehydration, hypovolemia, and treatment with antihypertensive medications); monitoring of orthostatic vital signs should be considered in patients who are vulnerable to hypotension
  • Use caution in patients with a history of seizures or with conditions that lower the seizure threshold
  • Possibility of suicide attempts is inherent in psychotic illness, and close supervision of high-risk patients should accompany drug therapy; prescriptions should be written for the smallest quantity of tablets consistent with good patient management in order to reduce the risk for overdose
  • Disruption of the body’s ability to reduce core body temperature has been attributed to antipsychotic agents; appropriate care is advised when prescribing for patients who will be experiencing conditions that may contribute to an elevation in core body temperature, e.g., exercising strenuously, exposure to extreme heat, receiving concomitant medication with anticholinergic activity, or being subject to dehydration
  • Esophageal dysmotility and aspiration associated with antipsychotic drug use; aspiration pneumonia is a common cause of morbidity and mortality in elderly patients; this medication and other antipsychotic drugs should be used cautiously in patients at risk for aspiration pneumonia
  • Leukopenia, neutropenia, and agranulocytosis
  • In clinical trials and postmarketing experience, events of leukopenia/neutropenia were reported temporally related to antipsychotic agents; instances of agranulocytosis (including fatal cases) were also reported
  • Possible risk factors for leukopenia/neutropenia include preexisting low white blood cell count (WBC) and a history of drug-induced leukopenia/neutropenia; patients with a preexisting low WBC or a history of drug-induced leukopenia/neutropenia should have their complete blood count (CBC) monitored frequently during the first few months of therapy and should discontinue the drug at the first sign of a decline in WBC in the absence of other causative factors
  • Patients with neutropenia should be carefully monitored for fever or other symptoms or signs of infection and treated promptly if such symptoms or signs occur; patients with severe neutropenia (absolute neutrophil count less than 1000/mm3) should discontinue therapy and have their WBC monitored until recovery
  • Hyperprolactinemia
    • As with other drugs that antagonize dopamine D2 receptors, this drug elevates prolactin levels; hyperprolactinemia may suppress hypothalamic GnRH, resulting in reduced pituitary gonadotropin secretion; this, in turn, may inhibit reproductive function by impairing gonadal steroidogenesis in both female and male patients
    • Galactorrhea, amenorrhea, gynecomastia, and impotence reported with prolactin-elevating compounds; long-standing hyperprolactinemia when associated with hypogonadism may lead to decreased bone density in both female and male patients
    • Tissue culture experiments indicate that approximately one-third of human breast cancers are prolactin-dependent in vitro, a factor of potential importance if the prescription of these drugs is contemplated in a patient with previously detected breast cancer
    • Neither clinical studies nor epidemiologic studies conducted to date have shown an association between chronic administration of this class of drugs and tumorigenesis in humans; the available evidence is considered too limited to be conclusive at this time
  • Metabolic changes
    • Atypical antipsychotics have been associated with metabolic changes that may increase cardiovascular/cerebrovascular risk
    • These metabolic changes include hyperglycemia, dyslipidemia, and body weight gain; while all atypical antipsychotic drugs have been shown to produce some metabolic changes, each drug in the class has its own specific risk profile
    • Increased risk for hyperglycemia and diabetes; in some cases, hyperglycemia concomitant with the use of atypical antipsychotics has been associated with ketoacidosis, hyperosmolar coma, or death
    • Undesirable alterations in lipids have been reported in patients treated with atypical antipsychotics
    • Monitor blood glucose of high-risk patients
  • Hyperglycemia and diabetes mellitus
    • Hyperglycemia, in some cases extreme and associated with ketoacidosis or hyperosmolar coma or death, reported; assessment of the relationship between atypical antipsychotic use and glucose abnormalities is complicated by the possibility of an increased background risk for diabetes mellitus in patients with schizophrenia and increasing incidence of diabetes mellitus in the general population
    • Relationship between atypical antipsychotic use and hyperglycemia-related adverse events is not completely understood; however, epidemiological studies suggest an increased risk for hyperglycemia-related adverse events in patients treated with atypical antipsychotics
    • Patients with an established diagnosis of diabetes mellitus who are started on atypical antipsychotics should be monitored regularly for worsening of glucose control; patients with risk factors for diabetes mellitus (eg, obesity, family history of diabetes) who are starting treatment with atypical antipsychotics should undergo fasting blood glucose testing at the beginning of treatment and periodically during treatment
    • Any patient treated with atypical antipsychotics should be monitored for symptoms of hyperglycemia including polydipsia, polyuria, polyphagia, and weakness; patients who develop symptoms of hyperglycemia during treatment with atypical antipsychotics should undergo fasting blood glucose testing; in some cases, hyperglycemia has resolved when the atypical antipsychotic was discontinued; however, some patients required the continuation of antidiabetic treatment despite the discontinuation of the suspect drug
  • Tardive dyskinesia
    • Tardive dyskinesia is a syndrome consisting of potentially irreversible, involuntary, dyskinetic movements, which may develop in patients treated with antipsychotic drugs; although the prevalence of the syndrome appears to be highest among the elderly, especially elderly women, it is impossible to rely on prevalence estimates to predict, at the inception of antipsychotic treatment, which patients are likely to develop the syndrome
    • Whether antipsychotic drug products differ in their potential to cause tardive dyskinesia is unknown; the risk of developing tardive dyskinesia and the likelihood that it will become irreversible are believed to increase as the duration of treatment and the total cumulative dose of antipsychotic administered increases; however, the syndrome can develop, although much less commonly, after relatively brief treatment periods at low doses
    • There is no known treatment for established cases of tardive dyskinesia although the syndrome may remit, partially or completely, if antipsychotic treatment is withdrawn; antipsychotic treatment itself, however, may suppress (or partially suppress) the signs and symptoms of the syndrome and thereby may mask the underlying process
    • The effect that symptomatic suppression has upon the long-term course of the syndrome is unknown; given these considerations, this treatment should be prescribed in a manner that is most likely to minimize the occurrence of tardive dyskinesia; chronic antipsychotic treatment should generally be reserved for patients who suffer from a chronic illness that is known to respond to antipsychotic drugs, and for whom alternative, equally effective, but potentially less harmful treatments are not available or appropriate
    • In patients who do require chronic treatment, the smallest dose and shortest duration of treatment producing a satisfactory clinical response should be sought; the need for continued treatment should be reassessed periodically; if signs and symptoms of tardive dyskinesia appear in a patient on therapy, drug discontinuation should be considered; however, some patients may require treatment with despite the presence of the syndrome
  • Neuroleptic malignant syndrome
    • A potentially fatal symptom complex, sometimes referred to as neuroleptic malignant syndrome (NMS), has been reported in association with the administration of antipsychotic drugs, including this medication; clinical manifestations include hyperpyrexia, muscle rigidity, altered mental status (including catatonic signs) and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac dysrhythmia); additional signs may include elevated creatine phosphokinase, myoglobinuria (rhabdomyolysis), and acute renal failure
    • The diagnostic evaluation of patients with this syndrome is complicated; in arriving at a diagnosis, it is important to identify the cases in which the clinical presentation includes both serious medical illness (eg, pneumonia, systemic infection, etc.) and untreated or inadequately treated extrapyramidal signs and symptoms (EPS)
    • Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system (CNS) pathology
    • The management of this syndrome should include immediate discontinuation of antipsychotic drugs and other drugs that are not essential to concurrent therapy, intensive symptomatic treatment and medical monitoring, and treatment of any concomitant serious medical problems for which specific treatments are available
    • There is no general agreement about specific pharmacological treatment regimens for NMS; if a patient requires antipsychotic drug treatment after recovery from NMS, the potential reintroduction of drug therapy should be carefully considered; the patient should be carefully monitored since recurrences of NMS have been reported
  • QT Prolongation
    • Prolongs QT interval; caution with other drugs/conditions that increase QTc; use of this medication should be avoided in combination with other drugs that are known to prolong QTc including Class IA (e.g., quinidine, procainamide) or Class III (eg, amiodarone, sotalol) antiarrhythmic medications, antipsychotic medications (eg, chlorpromazine, thioridazine), antibiotics (eg, gatifloxacin, moxifloxacin), or any other class of medications known to prolong the QTc interval (e.g., pentamidine, levomethadyl acetate, methadone)
    • Therapy should also be avoided in patients with known genetic susceptibility to congenital long QT syndrome and in patients with a history of cardiac arrhythmias; certain conditions may increase the risk for torsade de pointes and/or sudden death in association with the use of drugs that prolong the QTc interval; these conditions include bradycardia, hypokalemia or hypomagnesemia, concomitant use of other drugs that prolong QTc interval, presence of congenital prolongation of the QT interval, recent acute myocardial infarction and/or uncompensated heart failure
    • Caution is warranted when prescribing this medication with drugs that inhibit its metabolism and in patients with reduced activity of CYP2D6
    • Patients being considered for treatment who are at risk for significant electrolyte disturbances are recommended to have their baseline serum potassium and magnesium levels monitored periodically; hypokalemia (and/or hypomagnesemia) may increase the risk for QT prolongation and arrhythmia
    • Therapy should be avoided in patients with a history of significant cardiovascular illness, e.g., QT prolongation, recent acute myocardial infarction, uncompensated heart failure, or cardiac arrhythmia
    • Therapy should be discontinued in patients who are found to have persistent QTc measurements above 500 msec; if patients taking this medication experience symptoms that could indicate the occurrence of cardiac arrhythmias, eg, dizziness, palpitations or syncope, the prescriber should initiate further evaluation, including cardiac monitoring

Pregnancy and Lactation

  • There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to this medication during pregnancy; for more information contact the National Pregnancy Registry for Atypical Antipsychotics at 1-866-961-2388 or visit
  • Neonates whose mothers are exposed to antipsychotic drugs during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery
  • The limited data available on the use of iloperidone in pregnant women are not sufficient to inform a drug-associated risk for major birth defects and miscarriage
  • Extrapyramidal and/or withdrawal symptoms, including agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, and feeding disorder have been reported in neonates whose mothers were exposed to antipsychotic drugs during the third trimester of pregnancy
  • These symptoms varied in severity; some neonates recovered within hours or days without specific treatment; others required prolonged hospitalization; monitor neonates for extrapyramidal and/or withdrawal symptoms and manage symptoms appropriately
  • Lactation
    • There is no information regarding the presence of iloperidone or metabolites in human milk, its effects on breastfed children, or on human milk production; the drug is present in rat milk; because of its potential for serious adverse reactions in breastfed infants, advise women not to breastfeed during therapy
    • The transfer of radioactivity into the milk of lactating rats was investigated following a single dose of 5 mg/kg; the concentration of radioactivity in milk at 4 hr post-dose was near 10-fold greater than that in plasma at the same time; however, by 24 hours after dosing, the concentration of radioactivity in milk had fallen to values slightly lower than that in plasma; the metabolic profile in milk was qualitatively similar to that in plasma

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