Pimozide

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

In Canada, this drug has been used for a certain mental/mood disorder (chronic schizophrenia).

There may be a slightly increased risk of serious, possibly fatal side effects (such as heart failure, fast/irregular heartbeat, pneumonia) when this drug is used by older adults with dementia. This drug is not approved for the treatment of dementia-related behavior problems. Discuss the risks and benefits of this drug, as well as other effective and possibly safer treatments for dementia-related behavior problems, with the doctor.

Take this medication by mouth with or without food as directed by your doctor, usually once a day at bedtime.

The dosage is based on your medical condition, lab tests, and response to treatment. Your doctor may direct you to take a low dose at first, gradually increasing the dose to lower the chance of side effects such as shaking (tremors).

Do not take this drug more often or increase the dose. Your symptoms will not improve any faster, and the risk for heart rhythm problems will be increased. Follow your doctor's directions carefully.

Your doctor may order an electrocardiogram (EKG) and lab tests before you start this medication. These tests are to find out whether you are at risk for heart rhythm problems from pimozide. Keep all medical/lab appointments.

Other drugs, such as stimulant medications (such as methylphenidate, dextroamphetamine), may occasionally worsen tics. Before deciding to start pimozide, your doctor may try to reduce your tics by lowering the stimulant dose. Consult your doctor for more details.

Avoid eating grapefruit or drinking grapefruit juice while using this medication unless your doctor or pharmacist says you may do so safely. Grapefruit can increase the chance of side effects with this medicine. Ask your doctor or pharmacist for more details.

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.

Do not stop taking this medication without consulting your doctor. Your condition may become worse when the drug is suddenly stopped. Your dose may need to be gradually decreased.

Tell your doctor if your condition lasts or gets worse.

Before taking this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: blood problems (such as a low white blood cell count), a certain eye condition (glaucoma), dementia, depression, heart problems (such as slow/fast/irregular heartbeat, low blood pressure), slow movement of the gut/intestines (such as chronic constipation, blockage), kidney disease, liver disease, brain disorder/tumor/injury, drug/alcohol/substance abuse, breast cancer, Parkinson's disease, seizure disorder, a certain severe reaction to other antipsychotic-type medications (neuroleptic malignant syndrome-NMS), difficulty urinating (such as due to prostate problems).

This drug may make you dizzy or drowsy or cause vision changes. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Pimozide may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using pimozide, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using pimozide safely.

Before having surgery or imaging procedures (such as certain X-rays, CT scans) requiring the use of contrast dye (such as metrizamide), tell your doctor or dentist that you are using this medication and about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Children may be more sensitive to the side effects of this drug, especially uncontrolled movements.

Older adults may be more sensitive to the side effects of this drug, especially drowsiness, dizziness, lightheadedness, and QT prolongation (see above). Drowsiness, dizziness, and lightheadedness can increase the risk of falling.

During pregnancy, this medication should be used only when clearly needed. Babies born to mothers who have used this drug during the last 3 months of pregnancy may rarely develop symptoms including muscle stiffness or shakiness, drowsiness, feeding/breathing difficulties, or constant crying. If you notice any of these symptoms in your newborn especially during their first month, tell the doctor right away.

Since untreated mental/mood problems (such as schizophrenia) can be a serious condition, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately discuss with your doctor the benefits and risks of using this medication during pregnancy.

It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.

Do not share this medication with others.

Lab and/or medical tests (such as electrocardiogram-EKG, complete blood count) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Other medications can affect the removal of pimozide from your body, which may affect how pimozide works. Examples include aprepitant, azole antifungals (such as ketoconazole, itraconazole), HIV protease inhibitors (such as nelfinavir), letermovir, nefazodone, SSRI antidepressants (such as fluvoxamine, paroxetine, sertraline), ritonavir, tucatinib, zileuton, among others.

Tell your doctor or pharmacist if you are taking other products that cause drowsiness including alcohol, marijuana (cannabis), antihistamines (such as cetirizine, diphenhydramine), drugs for sleep or anxiety (such as alprazolam, diazepam, zolpidem), muscle relaxants, and opioid pain relievers (such as codeine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

Many drugs besides pimozide may affect the heart rhythm (QT prolongation). Examples include amiodarone, citalopram/escitalopram, chlorpromazine, dofetilide, procainamide, quinidine, ranolazine, sotalol, macrolide antibiotics (such as clarithromycin, erythromycin), among others.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: slow/shallow breathing, inability to wake up (coma).