Prochlorperazine belongs to the group of medications known as antipsychotics, and specifically to the family of antipsychotics called phenothiazines. It is used to treat the symptoms of psychotic disorders such as excessive anxiety, tension, confusion, delusions, and agitation. It works by affecting the chemical balance in the brain.

It also can be used to treat or prevent nausea and vomiting caused by the use of certain medications (e.g., cancer treatments) or motion sickness. When used for nausea and vomiting, the doses are much lower than those used for psychotic disorders. Accordingly, there are fewer side effects.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. 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.

For treatment of psychiatric illness, the initial recommended adult dose of prochlorperazine is 10 mg 3 or 4 times daily. Your doctor will gradually increase this dose until your symptoms are under control. The doses vary according to the condition being treated.

For treatment of nausea and vomiting, the recommended adult dose of prochlorperazine is usually 5 mg to 10 mg, 3 or 4 times daily.

Children's doses are usually based on weight.

Many things can affect the dose of 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.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

This medication should not be given to or taken by anyone who:

• is allergic to prochlorperazine or any ingredients of this medication
• is allergic to any of the phenothiazine-type medications
• is comatose or has a reduced level of consciousness
• is severely depressed
• is intoxicated or taking large doses of central nervous system depressants (barbiturates, alcohol, analgesics, sedatives, or antihistamines)
• has a medical condition known as pheochromocytoma
• has a severe heart disorder
• has bone marrow depression or other blood disorders
• has brain damage
• has liver damage
• has reduced kidney function

Do not give this medication to children undergoing surgery.

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.

• changes in menstrual period
• constipation (mild)
• decreased appetite
• decreased sexual ability or interest
• dizziness
• drowsiness
• dry mouth
• fatigue
• headache
• nasal congestion
• nausea
• sweating
• swelling or pain in breasts
• trouble sleeping
• urinary incontinence
• vomiting
• watering of mouth
• weight changes

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

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

• agitation
• bizarre dreams
• changes in ability to move
• inability to move eyes
• increased blinking or spasms of eyelid
• lip smacking or puckering
• loss of balance control
• restlessness or need to keep moving
• shuffling walk
• stiffness of arms or legs
• trembling and shaking of hands and fingers
• changes in blood pressure
• constipation (severe)
• dizziness or fainting when rising from sitting or lying position
• fast, slow, or irregular heartbeat
• flu-like symptoms (sudden lack of energy, fever, cough, sore throat)
• increased blood pressure
• mask-like face (reduced facial expression)
• secretion of milk (unusual)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• skin rash
• sunburn (severe)
• swelling hands, feet, ankles
• symptoms of urinary retention such as decrease in amount of urine, or difficult or painful urination
• vision changes (e.g., blurred vision, changes in colour vision, or difficulty seeing at night)
• trouble breathing, speaking, or swallowing

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

• nervous system problems (e.g., drooling, upward eye rolling movement, difficulty moving how and when you want, severe muscle stiffness, trembling)
• prolonged, painful, inappropriate erection of the penis
• seizures
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• symptoms of neuroleptic malignant syndrome (e.g., high fever, sweating, stiff muscles, fast heartbeat, fast breathing, feeling confused, drowsy or agitated)
• trouble speaking or swallowing

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.

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.

Abnormal heart rhythms: This medication can cause abnormal heart rhythms. Certain medications (e.g., sotalol, quinidine, chlorpromazine, pimozide, moxifloxacin, mefloquine, pentamidine, arsenic trioxide, tacrolimus) can increase the risk of a type of abnormal heart rhythm called QT prolongation, and should not be used in combination with prochlorperazine.

You are more at risk for this type of abnormal heart rhythm and its complications if you:

• are female
• are older than 65 years of age
• have a family history of sudden cardiac death
• have a history of heart disease or abnormal heart rhythms
• have a slow heart rate
• have congenital prolongation of the QT interval
• have diabetes
• have had a stroke
• have low potassium, magnesium, or calcium levels
• have nutritional deficiencies

Alcohol: The effects of alcohol may be increased by the use of this medication.

Behaviour changes: Although prochlorperazine is intended to have a calming effect on thought processes, occasionally it can cause agitation, anxiety, or increased psychotic behaviours.

If you experience these side effects or notice them in a family member who is taking this medication, contact your doctor immediately. You should be closely monitored by your doctor for emotional and behaviour changes while taking this medication.

Blood clots: This medication may increase the chance of blood clot formation, causing reduction of blood flow to organs or the extremities.

If you have a history of clotting you may be at increased risk of experiencing blood clot-related problems such as heart attack, stroke, or clots in the deep veins of your leg. Discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms such as sharp pain and swelling in the leg, difficulty breathing, chest pain, blurred vision or difficulty speaking, contact your doctor immediately.

Blood counts: This medication can decrease the number of neutrophils (a type of white blood cell that helps fight infection), red blood cells (which carry oxygen), and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, contact your doctor immediately.

Body temperature: Prochlorperazine affects the body's natural mechanisms for keeping body temperature within a normal range. People who exercise vigorously, are exposed to extreme heat, are dehydrated, or are taking anticholinergic medications (e.g., benztropine, oxybutynin) are more at risk. Contact your doctor as soon as possible if you feel very hot and are unable to cool.

Exposure to extreme heat or being in heat for a long period of time can result in severe overheating that can be fatal.

Constipation: Prochlorperazine slows down the speed that things travel through the digestive system causing constipation. If constipation develops, talk to your doctor as soon as possible. Constipation that is allowed to continue can become a serious problem.

Depression: Prochlorperazine may cause depression or make the symptoms of depression worse. If you have depression or a history of depression, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of depression such as poor concentration, changes in weight, changes in sleep, decreased interest in activities, or notice them in a family member who is taking this medication, contact your doctor as soon as possible.

Diabetes: Prochlorperazine may cause an increase in blood sugar levels and glucose tolerance may change. You may find it necessary to monitor your blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Contact your doctor as soon as possible if you develop signs of high blood sugar, such as a fruity odour to the breath, increased thirst, hunger, and increased need to urinate overnight.

Drowsiness/reduced alertness: This medication may cause drowsiness or dizziness. Do not drive, operate machinery, or perform other potentially hazardous tasks until you have determined how this medication affects you.

Glaucoma: This medication may make the symptoms of glaucoma worse. If you have glaucoma, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: People taking this medication may have changes in liver function that produce abnormal liver test results. Your doctor will recommend regular liver tests while you are taking this medication. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Movement disorders: Prochlorperazine, like other antipsychotic medications can cause difficulty with daily movements. If you notice a fine tremor, difficulty moving muscles, unusual stiffness and trouble starting to move, contact your doctor as soon as possible.

Neuroleptic malignant syndrome (NMS): Prochlorperazine, like other antipsychotic medications, can cause a potentially fatal syndrome known as neuroleptic malignant syndrome (NMS). Get immediate medical attention if you notice symptoms of NMS such as high fever, muscle stiffness, confusion or loss of consciousness, sweating, racing or irregular heartbeat, or fainting.

Pesticides: People who take prochlorperazine are cautioned against exposure to certain types of insecticides, called organophosphorus insecticides.

Prostate problems: Prochlorperazine may make the symptoms of prostate problems worse. If you have a history of prostate problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Seizures: The frequency of seizures may increase if you have a seizure disorder and are taking prochlorperazine. If you have a history of epilepsy or medical conditions that increase your risk of seizures, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Stopping the medication: If this medication is stopped suddenly, you may experience withdrawal symptoms similar to the unwanted movements described in the section "Tardive Dyskinesia." If you have been taking this medication for a while, it should be stopped gradually as directed by your doctor.

Tardive Dyskinesia (TD): Prochlorperazine, like some other antipsychotic medications may cause tardive dyskinesia (TD) to develop. TD is a potentially irreversible syndrome of involuntary, repetitive movements of the face and tongue muscles. Although TD appears most commonly in seniors, especially women, it is impossible to predict who will develop TD. The risk of developing TD increases with higher doses and long-term treatment. If you experience muscle twitching or abnormal movements of the face or tongue, contact your doctor as soon as possible.

Pregnancy: The safe use of this medication during pregnancy has not been established. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Babies born to mothers who take this medication during the last 3 months of pregnancy may experience withdrawal symptoms including agitation, trouble feeding and poor muscle tone.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking prochlorperazine, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: Children with an illness involving fever or dehydration seem to be much more susceptible than adults to reactions involving the muscles. In these cases, prochlorperazine should be used under close supervision and at low doses.

Prochlorperazine should not be given to children under 2 years of age or weighing less than 9 kg, unless it is considered potentially lifesaving.

Seniors: Those over 55 years of age may be more likely to experience adverse effects from this medication. Seniors with dementia-related psychosis who are treated with antipsychotics are at an increased risk of death.

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

• aclidinium
• alcohol
• amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
• antiarrhythmics (e.g., dronedarone, disopyramide, procainamide, quinidine)
• antihistamines (e.g., azelastine, bilastine, cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine, rupatadine)
• anti-Parkinson's medications (e.g., amantadine, apomorphine, bromocriptine, entacapone, levodopa, pramipexole, ropinirole, rotigotine)
• antipsychotics (e.g., cariprazine, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• atropine
• barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
• belladonna
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
• benztropine
• botulinum toxin
• brimonidine
• buprenorphine
• bupropion
• butorphanol
• caffeine
• cannabis
• chloral hydrate
• clonidine
• darifenacin
• dimenhydrinate
• diphenoxylate
• domperidone
• donepezil
• efavirenz
• ephedrine
• epinephrine
• esketamine
• fesoterodine
• flunarizine
• galantamine
• general anesthetics (medications used to put people to sleep before surgery)
• glucagon
• glycopyrrolate
• hydroxychloroquine
• ipratropium
• lithium
• methadone
• metoclopramide
• methylphenidate
• mirabegron
• mirtazapine
• monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, rasagiline, selegiline, tranylcypromine)
• muscle relaxants (e.g., baclofen, cyclobenzaprine, methocarbamol, orphenadrine)
• nabilone
• narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone, tapentadol, tramadol)
• nitroglycerin
• oxybutynin
• potassium chloride
• prucalopride
• pseudoephedrine
• rivastigmine
• saquinavir
• seizure medications (e.g., clobazam, levetiracetam, phenobarbital, phenytoin, primidone, topiramate, valproic acid)
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• serotonin/norepinephrine reuptake inhibitors (SNRIs; e.g., desvenlafaxine, duloxetine, venlafaxine)
• solifenacin
• tetrabenazine
• thalidomide
• theophylline
• thiazide diuretics (water pills; e.g., hydrochlorothiazide, indapamide, metolazone)
• tiotropium
• tolterodine
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, imipramine)
• trospium
• tryptophan
• umeclidinium
• zolpidem
• zopiclone

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.