How does this medication work? What will it do for me?

Pimozide belongs to the class of medications called antipsychotics. It is used to manage symptoms of certain types of chronic schizophrenia. It works by affecting the way messages are sent in the central nervous system.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

2 mg
Each round, white, flat-faced, bevelled-edge, scored tablet, engraved "PIM" over "2" on one side, contains pimozide 2 mg. Nonmedicinal ingredients: anhydrous lactose, croscarmellose sodium, and magnesium stearate.

4 mg
Each round, light green, flat-faced, bevelled-edge, scored tablet, engraved "PIM" over "4" on  one side, contains pimozide 4 mg. Nonmedicinal ingredients: anhydrous lactose, croscarmellose sodium, D&C Yellow No. 10 Aluminum Lake, FD&C Blue No. 2 Aluminum Lake, and magnesium stearate.

How should I use this medication?

Adults: The recommended starting dose of pimozide ranges from 2 mg to 4 mg once daily, taken in the morning. Your doctor will gradually increase your dose to a maximum of 20 mg daily. The goal is to find the dose where the best effects occur with the least side effects.

Seniors: The recommended starting dose of pimozide ranges from 1 mg to 2 mg once daily, taken in the morning. Your doctor will gradually increase your dose to a maximum of 20 mg daily. The goal is to find the dose where the best effects occur with the least side effects.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take pimozide if you:

  • are allergic to pimozide or to any of the ingredients of the medication
  • are sedated or is in a comatose state
  • are taking any of the classes of medications known as "azole" antifungals, antiviral protease inhibitors, or macrolide antibiotics (erythromycins)
  • are taking sertraline, citalopram, escitalopram, or paroxetine
  • have a depressive disorder
  • have a family history of certain types of abnormal heart rhythms or has certain types of abnormal heart rhythms themselves
  • have a severely reduced heart rate
  • have a blood disorder
  • have a liver disorder
  • have low blood potassium or magnesium levels
  • have Parkinson's disease
  • have reduced kidney function

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • blurred vision or other vision problems
  • constipation
  • decreased sweating
  • dizziness, lightheadedness, or fainting when rising from a lying or sitting position
  • drowsiness
  • dry mouth
  • fatigue
  • sinus congestion

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • difficulty speaking
  • difficulty swallowing
  • dizziness or fainting not associated with rising from a lying or sitting position
  • excessive sweating
  • fast or irregular heartbeat
  • inability to move eyes
  • increased blinking or eyelid spasms
  • lack of facial expression
  • lip smacking or puckering
  • loss of balance control
  • menstrual changes
  • mood or behaviour changes
  • muscle spasms, especially of the face, neck, or back
  • puffing of cheeks
  • rapid or worm-like movements of tongue
  • restlessness or need to keep moving
  • shuffling walk
  • skin rash and itching
  • slowed movements
  • sore throat and fever
  • stiffness of arms or legs
  • swelling of face
  • swelling or soreness of breasts (less common in men)
  • trembling and shaking of fingers and hands
  • uncontrolled chewing movements or uncontrolled movements of the neck, trunk, arms, or legs, including twisting movements
  • unusual bleeding or bruising
  • unusual facial expressions or body positions
  • unusual secretion of milk (rare in men)
  • yellow eyes or skin

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • coma
  • convulsions (seizures)
  • difficult or unusually fast breathing
  • fast heartbeat or irregular pulse
  • loss of consciousness (fainting)
  • high fever
  • high or low (irregular) blood pressure
  • increased sweating
  • loss of bladder control
  • severe dizziness
  • severe muscle stiffness
  • severe muscle trembling, jerking, or stiffness
  • severe trouble breathing
  • severe uncontrolled movements

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood pressure: People who take pimozide may develop very low blood pressure causing dizziness and lightheadedness. Some individuals, especially seniors or those who are debilitated, have had temporary low blood pressure for several hours after taking the medication.

Drowsiness/reduced alertness: Pimozide may reduce alertness, especially at the start of treatment. Alcohol may increase these effects. Avoid tasks requiring alertness, such as driving or operating machinery, until you determine if the medication affects you this way.

Epilepsy: Since pimozide may increase the risk of seizures, people with epilepsy should be closely monitored by their doctor while taking this medication.

Grapefruit juice: Grapefruit juice prevents pimozide from being broken down (metabolized) in the body. Avoid drinking grapefruit juice if you take pimozide.

Heart problems: People with heart problems taking pimozide should be closely monitored by their doctor.

Liver disease: People with liver disease should be closely monitored by their doctor while taking this medication because pimozide is broken down (metabolized) in the liver.

Stopping the medication: Do not stop taking this medication without speaking to your doctor. Stopping suddenly may lead to uncomfortable side effects - your doctor may wish to gradually reduce your dose over time.

Tardive dyskinesia (TD): As with all antipsychotic medications, a syndrome called TD may occur for some people on long-term therapy or after they stop taking the medication. The syndrome's main features are rhythmical involuntary movements of the tongue, face, mouth, or jaw. Tell the doctor if you notice these symptoms in yourself or someone else taking pimozide.

Pregnancy: The safe of use of pimozide during pregnancy has not been established. It should not be taken by women who are or may become pregnant, particularly during the first trimester of pregnancy, unless in the opinion of the doctor the benefits outweigh the risks.

Breast-feeding: Pimozide may pass into breast milk. If taking pimozide is considered essential, stop breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children. Pimozide is not recommended for children.

What other drugs could interact with this medication?

There may be an interaction between pimozide and any of the following:

  • alcohol
  • amiodarone
  • astemizole
  • azithromycin
  • "azole" antifungals (e.g., ketoconazole, fluconazole)
  • citalopram
  • clarithromycin
  • desipramine
  • disopyramide
  • domperidone
  • doxepin
  • erythromycin
  • escitalopram
  • fluconazole
  • fluoxetine
  • grapefruit juice
  • haloperidol
  • imipramine
  • maprotiline
  • mefloquine
  • methadone
  • moxifloxacin
  • nefazodone
  • norfloxacin
  • opiates (e.g., morphine)
  • phenothiazines (e.g., chlorpromazine, perphenazine)
  • procainamide
  • protease inhibitors (e.g., saquinavir, ritonavir)
  • quinine
  • sotalol
  • terfenadine
  • tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.