Pimozide Side Effects

Medically reviewed by Drugs.com. Last updated on Sep 5, 2024.

Applies to pimozide: oral tablet.

Precautions

It is very important that your doctor should check the progress of you or your child at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects. Your doctor may want also to check your heart rhythm while you are using this medicine.

You should not use this medicine if you or your child are using the following medicines: arsenic trioxide (Trisenox®), cisapride (Propulsid®), dolasetron mesylate (Anzemet®), droperidol (Dridol®, Inapsine®), levomethadyl acetate (Orlaam®), methylphenidate (Ritalin®), pemoline (Cylert®), pentamidine (Nebupent®), probucol, tacrolimus (Prograf®), zileuton (Zyflo®), amphetamines (such as Desoxyn®, Dexedrine®), medicine for heart rhythm problems (such as amiodarone, disopyramide, dofetilide, procainamide, quinidine, sotalol, Betapace®, Cardioquin®, Cordarone®, Norpace®, Procanbid®, Quinaglute®, or Tikosyn®), medicine for depression (such as amitriptyline, citalopram, escitalopram, fluoxetine, fluvoxamine, nefazodone, nortriptyline, paroxetine, sertraline, Celexa®, Elavil®, Lexapro™, Luvox®, Pamelor®, Paxil®, Prozac®, Sarafem®, Serzone®, Vivactil®, or Zoloft®), certain antibiotics (such as azithromycin, clarithromycin, dirithromycin, erythromycin, gatifloxacin, itraconazole, ketoconazole, levofloxacin, moxifloxacin, sparfloxacin, troleandomycin, Avelox®, Biaxin®, Ery-tab®, Levaquin®, Nizoral®, Sporanox®, Tao®, Tequin®, Zagam®, or Zithromax®), medicine to treat HIV infection (such as indinavir, nelfinavir, ritonavir, saquinavir, Crixivan®, Fortovase®, Invirase®, Norvir®, or Viracept®), medicine to treat malaria (such as halofantrine, mefloquine, Halfan®, or Lariam®), or medicine to treat mental illness (such as chlorpromazine, loxapine, mesoridazine, molindone, perphenazine, prochlorperazine, quetiapine, thioridazine, thiothixene, ziprasidone, Compazine®, Geodon®, Mellaril®, Serentil®, or Seroquel®). Using these medicines together with pimozide may increase risk for more serious side effects.

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. Contact your doctor right away if you or your child have any symptoms of heart rhythm problems, such as fast, pounding, or uneven heartbeats.

This medicine may cause tardive dyskinesia (a movement disorder). Stop using this medicine and check with your doctor right away if you or your child 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.

Check with your doctor right away if you or your child are having convulsions (seizures); difficulty with breathing; a fast heartbeat; 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).

Stop using this medicine and check with your doctor if you notice any signs of fever, chills, or sore throat. These could be symptoms of an infection resulting from low white blood cell counts.

Do not suddenly Stop taking pimozide without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping completely. This will allow your body time to adjust and help to avoid worsening of your medical condition.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; medicine for seizures or barbiturates; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you or your child are using this medicine.

This medicine may cause some people to become dizzy, drowsy, or less alert or to have blurred vision or muscle stiffness, especially as the amount of medicine is increased. Even if you take pimozide at bedtime, you may feel drowsy or less alert on arising. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert, not able to see well, or if you do not have good muscle control.

Although not a problem for many patients, dizziness, lightheadedness, or fainting may occur when you get up from a sitting or lying position. Getting up slowly may help. If the problem continues or gets worse, check with your doctor.

Before having any kind of surgery, dental treatment, or emergency treatment, tell the medical doctor or dentist in charge that you are using this medicine. Taking pimozide together with medicines that are used during surgery or dental or emergency treatment may increase the CNS depressant effects.

Pimozide may cause dryness of the mouth. For temporary relief, use sugarless gum or candy, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

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 pimozide

Along with its needed effects, pimozide 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 pimozide:

Get emergency help immediately if any of the following symptoms of overdose occur while taking pimozide:

Symptoms of overdose

• coma
• dizziness (severe)
• muscle trembling, jerking, or stiffness (severe)
• troubled breathing (severe)
• uncontrolled movements (severe)

Other side effects of pimozide

Some side effects of pimozide 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 pimozide: oral tablet.

General adverse events

The most common side effects include somnolence, hyperhidrosis, nocturia, and dizziness.^[Ref]

Nervous system

• Very common (10% or more): Somnolence (up to 25%), dizziness (up to 11%)
• Common (1% to 10%): Extrapyramidal disorder, akathisia, headache, lethargy, tremor, hyperkinesia, limb tremor, torticollis
• Uncommon (0.1% to 1%): Bradykinesia, cogwheel rigidity, dyskinesia, dystonia, dysarthria
• Frequency not reported: Neuroleptic malignant syndrome, grand mal convulsion, tardive dyskinesia, electroencephalogram abnormal, motor restlessness, hyperreflexia, opisthotonos, drowsiness, sedation, speech disorder, handwriting change, taste change, akinesia, parkinsonism, fainting
• Postmarketing reports: Seizure^[Ref]

Extrapyramidal symptoms typically occurred during the first few days of treatment and involved mild to moderate Parkinson-like symptoms. This disorder is usually dose-related, with an increased occurrence and severity of symptoms with high doses; symptoms decreased or disappeared with lower doses. While these symptoms were usually reversible, a few cases of persistent symptoms required discontinuation.

Grand mal seizures occurred at doses greater than 20 mg/day.^[Ref]

Psychiatric

• Very common (10% or more): Adverse behavior effect (up to 22.2%)
• Common (1% to 10%): Depression, agitation, insomnia, abnormal dreams, restlessness, nervous
• Frequency not reported: Libido decreased/lost, excitement^[Ref]

Other

• Very common (10% or more): Asthenia (up to 13.8%)
• Common (1% to 10%): Extreme exhaustion
• Uncommon (0.1% to 1%): Face edema
• Frequency not reported: Neonatal drug withdrawal syndrome, body temperature dysregulation, hypothermia
• Postmarketing reports: Sudden, unexplained death, hyperpyrexia, thirst^[Ref]

Sudden, unexpected deaths have occurred at doses greater than 20 mg/day.^[Ref]

Dermatologic

• Very common (10% or more): Hyperhidrosis (up to 13%)
• Common (1% to 10%): Sebaceous gland overactivity, rash
• Uncommon (less than 1%): Pruritus
• Frequency not reported: Urticaria, skin irritation^[Ref]

Genitourinary

• Very common (10% or more): Nocturia (up to 12%)
• Common (1% to 10%): Urinary frequency, erectile dysfunction
• Uncommon (0.1% to 1%): Amenorrhea
• Frequency not reported: Galactorrhea, menstrual disorder, breast secretions, impotence^[Ref]

Gastrointestinal

• Common (1% to 10%): Constipation, dry mouth, vomiting, increased salivation/salivary hypersecretion, dysphagia
• Frequency not reported: Diarrhea, nausea, gastrointestinal distress
• Postmarketing reports: Gingival hyperplasia^[Ref]

Gingival hyperplasia occurred in animal models at high doses, but was reversible after discontinuation.^[Ref]

Musculoskeletal

• Common (1% to 10%): Muscle rigidity, myalgia
• Uncommon (0.1% to 1%): Muscle spasms
• Frequency not reported: Rigidity, neck rigidity, muscle cramps, muscle tightness, stooped posture^[Ref]

Ocular

• Common (1% to 10%): Vision blurred, visual disturbance
• Uncommon (0.1% to 1%): Oculogyric crisis
• Frequency not reported: Sensitivity of eyes to light, decrease accommodation, spots before eyes, periorbital edema, cataracts^[Ref]

Metabolic

• Common (1% to 10%): Anorexia, weight increased
• Frequency not reported: Hyperglycemia, hyponatremia, appetite increase, weight loss^[Ref]

Hyperglycemia occurred in patients with preexisting diabetes.^[Ref]

Cardiovascular

• Common (1% to 10%): ECG abnormal
• Frequency not reported: Torsade de Pointes, ventricular tachycardia/tachycardia, ventricular fibrillation, chest pain, postural hypotension/hypotension, hypertension, palpitations
• Postmarketing reports: Cardiac arrest, venous thromboembolism, deep vein thrombosis^[Ref]

Electrocardiographic changes include prolongation of the QT interval, flattening/notching/inversion of the T wave, and the appearance of U waves.^[Ref]

Endocrine

• Frequency not reported: Blood prolactin increases, gynecomastia^[Ref]

Renal

• Frequency not reported: Glycosuria^[Ref]

Hematologic

• Postmarketing reports: Hemolytic anemia^[Ref]

Respiratory

• Postmarketing reports: Pulmonary embolism^[Ref]

See also:

Frequently asked questions

• What drugs cause tardive dyskinesia?

Further information

Pimozide 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