Fanapt Side Effects

Generic name: iloperidone

Medically reviewed by Drugs.com. Last updated on Feb 13, 2025.

Note: This document provides detailed information about Fanapt Side Effects associated with iloperidone. Some dosage forms listed on this page may not apply specifically to the brand name Fanapt.

Applies to iloperidone: oral tablet.

Precautions

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

This medicine may cause serious allergic reactions, including anaphylaxis, which can be life-threatening and require immediate medical attention. Call your doctor right away if you have itching, hives, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth after you take this medicine.

This medicine can cause changes in heart rhythms, such as a condition called QT prolongation. It may change the way your heart beats and cause fainting or serious side effects in some patients. Call your doctor right away if you have any symptoms of heart rhythm problems, such as dizziness, feeling faint, or a fast, pounding, or irregular heartbeat.

Check with your doctor right away if you have any of the following symptoms while using this medicine: convulsions (seizures), difficulty with breathing, a fast heartbeat, a high fever, high or low blood pressure, increased sweating, loss of bladder control, severe muscle stiffness, unusually pale skin, or tiredness. These could be symptoms of a serious condition called neuroleptic malignant syndrome (NMS).

This medicine may cause tardive dyskinesia (a movement disorder). Check with your doctor right away if you have any of the following symptoms while taking this medicine: lip smacking or puckering, puffing of the cheeks, rapid or worm-like movements of the tongue, uncontrolled chewing movements, or uncontrolled movements of the arms and legs.

This medicine may increase prolactin blood levels if used for a long time. Check with your doctor if you have breast swelling or soreness, unusual breast milk production, absent, missed, or irregular menstrual periods, stopping of menstrual bleeding, loss in sexual ability, desire, drive, or performance, decreased interest in sexual intercourse, or an inability to have or keep an erection.

This medicine may increase the amount of sugar in your blood. Check with your doctor right away if you have increased thirst or increased urination. If you have diabetes, you may notice a change in the results of your urine or blood sugar tests. If you have any questions, check with your doctor.

This medicine may increase your weight. Your doctor may need to check your weight on a regular basis while you are using this medicine.

Dizziness, lightheadedness, or fainting may occur, especially when you get up from a lying or sitting position suddenly. Getting up slowly may help. If this problem continues or gets worse, check with your doctor.

Iloperidone can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.

This medicine may make it more difficult for your body to cool itself down. Use care not to become overheated during exercise or hot weather since overheating may result in heat stroke. Also, use extra care not to become too cold while you are taking risperidone. If you become too cold, you may feel drowsy, confused, or clumsy.

Iloperidone may cause some people to be agitated, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed. If you or your caregiver notice any of these side effects, tell your doctor right away.

This medicine may cause drowsiness, trouble with thinking, trouble with controlling body movements, or trouble with your vision, which may lead to falls, fractures, or other injuries. Make sure you know how you react to this medicine before you drive, use machines, or do other jobs that require you to be alert, well-coordinated, or able to think or see well.

Avoid drinking alcohol while you are using this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects of Fanapt

Along with its needed effects, iloperidone (the active ingredient contained in Fanapt) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking iloperidone:

Other side effects of Fanapt

Some side effects of iloperidone may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For healthcare professionals

Applies to iloperidone: oral tablet.

General adverse events

The most commonly reported side effects included dizziness, somnolence, and tachycardia.^[Ref]

Nervous system

• Very common (10% or more): Dizziness (up to 20%), somnolence (up to 15%)
• Common (1% to 10%): Akathisia, dyskinesia, dystonia, extrapyramidal disorder, lethargy, tremor
• Uncommon (0.1% to 1%): Amnesia, bradykinesia, difficulty in walking, nystagmus, paresthesia, parkinsonism, psychomotor hyperactivity, vertigo
• Rare (0.01% to 0.1%): Restless legs syndrome^[Ref]

Cardiovascular

• Very common (10% or more): Tachycardia (up to 12%)
• Common (1% to 10%): Hypotension, orthostatic hypotension, palpitations
• Uncommon (0.1% to 1%): Edema due to cardiac disease, general edema, pitting edema
• Rare (0.01% to 0.1%): Acute cardiac failure, arrhythmia, congestive cardiac failure, first degree atrioventricular block^[Ref]

In an open-label QTc study of 160 patients with schizophrenia or schizoaffective disorder, use of 12 mg twice a day was associated with a QT prolongation of 9 msec. When this drug was administered concomitantly with paroxetine 20 mg once a day (CYP450 2D6-inhibitor) or ketoconazole 200 mg twice a day (CYP450 3A4-inhibitor), the mean QTc interval prolongation from baseline increased to 19 msec.^[Ref]

Gastrointestinal

• Very common (10% or more): Dry mouth (up to 10%), nausea (up to 10%)
• Common (1% to 10%): Abdominal discomfort, diarrhea
• Uncommon (0.1% to 1%): Fecal incontinence, gastritis, mouth ulceration, salivary hypersecretion
• Rare (0.01% to 0.1%): Aphthous stomatitis, duodenal hernia, hiatus hernia, hyperchlorhydria, lip ulceration, reflux esophagitis, stomatitis
• Postmarketing reports: Lip swelling, mouth swelling, oropharyngeal swelling, tongue swelling^[Ref]

Respiratory

• Common (1% to 10%): Dyspnea, nasal congestion, nasopharyngitis, upper respiratory tract infection
• Uncommon (0.1% to 1%): Asthma, epistaxis, nasal dryness, rhinorrhea, sinus congestion
• Rare (0.01% to 0.1%): Dry throat, exertional dyspnea, sleep apnea syndrome
• Postmarketing reports: Throat swelling^[Ref]

Psychiatric

• Common (1% to 10%): Aggression, delusion, restlessness
• Uncommon (0.1% to 1%): Anorgasmia, bulimia nervosa, catatonia, confusional state, delirium, hostility, impulse-control disorder, libido decreased, major depression, mania, mood swings, obsessive-compulsive disorder, panic attack, paranoia^[Ref]

Ocular

• Common (1% to 10%): Allergic conjunctivitis, blurred vision, conjunctivitis
• Uncommon (0.1% to 1%): Blepharitis, cataract, conjunctival hyperemia, dry eye, eyelid edema, eye swelling, hyperemia, lenticular opacities^[Ref]

Genitourinary

• Common (1% to 10%): Ejaculation failure, erectile dysfunction, urinary incontinence
• Uncommon (0.1% to 1%): Amenorrhea, breast pain, dysuria, enuresis, pollakiuria, testicular pain
• Rare (0.01% to 0.1%): Menorrhagia, metrorrhagia, menstruation irregular, postmenopausal hemorrhage, prostatitis, urinary retention
• Postmarketing reports: Retrograde ejaculation^[Ref]

Musculoskeletal

• Common (1% to 10%): Muscle spasms, musculoskeletal stiffness, myalgia
• Rare (0.01% to 0.1%): Torticollis^[Ref]

Metabolic

• Common (1% to 10%): Weight decreased, weight increased
• Uncommon (0.1% to 1%): Dehydration, fluid retention, hypokalemia, increased appetite, polydipsia psychogenic, thirst^[Ref]

Other

• Common (1% to 10%): Fatigue
• Uncommon (0.1% to 1%): Hyperthermia, tinnitus^[Ref]

Renal

• Uncommon (0.1% to 1%): Nephrolithiasis
• Rare (0.01% to 0.1%): Acute renal failure^[Ref]

Dermatologic

• Common (1% to 10%): Rash
• Postmarketing reports: Facial swelling, pruritus, urticaria^[Ref]

Hematologic

• Uncommon (0.1% to 1%): Anemia, hematocrit decreased/lowered, hemoglobin decreased, iron deficiency anemia, neutrophil count increased
• Rare (0.01% to 0.1%): Leukopenia^[Ref]

Endocrine

• Uncommon (0.1% to 1%): Hypothyroidism
• Rare (0.01% to 0.1%): Gynecomastia^[Ref]

Hepatic

• Uncommon (0.1% to 1%): Cholelithiasis^[Ref]

Hypersensitivity

• Postmarketing reports: Anaphylaxis, angioedema, hypersensitivity reactions^[Ref]

See also:

Further information

Fanapt side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer