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

Methotrimeprazine belongs to the class of medications called phenothiazines. It is used to treat mental and emotional disorders, including schizophrenia, manic-depressive syndromes and other psychotic disorders. It can also be used in conditions associated with anxiety and tension, as a pain reliever (for certain types of pain), as a sedative, and for nausea and vomiting caused by certain conditions.

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?

July 27, 2011 

Methotrimeprazine by Pro Doc Limitee is no longer being manufactured for sale in Canada. For brands that may still be available, search under methotrimeprazine. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

The dose of this medication varies widely depending on the condition being treated and the circumstances and age of the person being treated.

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, contact your doctor or pharmacist for advice. Do not take a double dose to make up for a missed one.

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

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 methotrimeprazine if you:

  • are allergic to methotrimeprazine, or any ingredient of this medication
  • are allergic to other phenothiazines (e.g., chlorpromazine)
  • are excessively sedated by alcohol, sleeping pills, tranquilizers, pain relievers, or narcotics
  • have a blood disorder
  • have liver problems
  • have brain damage
  • have pheochromocytoma (a tumour in the adrenal glands)
  • are being treated with regional or spinal pain relief (epidural infusion)
  • are experiencing severely low blood pressure or severe heart disorder

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.

  • decreased sweating
  • drowsiness (appears early in treatment and gradually disappears during the first weeks or with an adjustment in the dosage)
  • dryness of the mouth
  • flu-like symptoms
  • increased skin sensitivity to sunlight
  • weight gain

Although most of the 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 urinating
  • high blood sugar (symptoms include increased thirst, decreased appetite, nausea and vomiting)
  • low blood pressure (symptoms include dizziness, especially when moving to a standing position)
  • new or worsening constipation
  • restlessness or inability to remain still
  • 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)
  • vision changes

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

  • abdominal pain
  • allergic reactions, such as skin rash, redness, or itching
  • fast or irregular heartbeat, high or low blood pressure
  • increased sweating, confusion, or reduced consciousness
  • muscle twitching or uncontrolled movements of the mouth, tongue, face, or jaw
  • painful erection lasting more than 4 hours
  • respiratory infection, fever, flu-like symptoms, coughing, difficult or fast breathing
  • shaking, muscle stiffness, body spasm, impairment of voluntary movement, upward eye rolling, exaggeration of reflexes or drooling
  • seizures
  • symptoms of a blood clot (e.g., sharp pain in the foot or unexplained leg swelling, pain, redness, or tenderness, sharp pain in the chest, coughing blood, or sudden shortness of breath)

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.

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

If you have heart disease and abnormal heart rhythms, or are taking certain medications (e.g., verapamil, atazanavir), 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.

Blood clots: Rarely, 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.

Body temperature: Methotrimeprazine, like other antipsychotic medications, may interfere with your body's ability to regulate body temperature. People who exercise vigorously, who 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.

Take care to avoid overheating during strenuous exercise or in hot temperatures, and avoid becoming dehydrated by drinking enough fluids.

Diabetes: Methotrimeprazine may increase blood sugar for people with diabetes or those who are at risk for diabetes. If you have diabetes, monitor your blood sugar frequently as recommended by your doctor. If you experience symptoms of high blood sugar (e.g., increased urination, increased thirst, increased eating, and weakness) while taking this medication, contact your doctor.

Dizziness/lightheadedness: In high doses, dizziness or lightheadedness when getting up from a sitting or lying position may be experienced at the start of treatment. To reduce the possibility of experiencing this, rise slowly from a sitting or lying position.

Drowsiness/reduced alertness: Methotrimeprazine can cause drowsiness and reduced alertness, especially during the first few days of treatment. Avoid driving, operating machinery, or performing other tasks that require mental alertness until you have determined how this medication affects you.

Medical conditions: If you have arteriosclerosis, heart problems, glaucoma, or 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.

Neuroleptic malignant syndrome (NMS): This medication may cause a potentially fatal reaction called neuroleptic malignant syndrome (NMS). If you develop symptoms of NMS, such as muscle stiffness, fever, confusion, sweating, or irregular heartbeat, stop taking this medication and seek immediate medical attention.

Tardive dyskinesia: People taking this medication may develop tardive dyskinesia, a syndrome of uncontrolled body movements. This syndrome may be irreversible. If you develop uncontrolled or unusual body movements, contact your doctor as soon as possible.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. Infants born to mothers who used methotrimeprazine in the later part of pregnancy have had abnormal muscle movement and withdrawal symptoms, including decreased muscle tone, sleepiness, difficulty feeding and severe difficulty breathing after birth. These symptoms can be severe and need medical attention. If you become pregnant while taking this medication, contact your doctor immediately.

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

Seniors: Seniors with dementia who take this medication may be at an increased risk of death due either heart disease or infections compared to seniors who are not taking this medication. The use of methotrimeprazine by older adults is not recommended.

What other drugs could interact with this medication?

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

  • acetylcholinesterase inhibitors (e.g., donepezil, galantamine, rivastigmine)
  • aclidinium
  • alcohol
  • alfuzosin
  • alpha/beta agonists (e.g., epinephrine, norepinephrine)
  • amiodarone
  • antacids (e.g., aluminum hydroxide, magnesium hydroxide)
  • antihistamines (e.g., cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine)
  • antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
  • amphetamines (e.g., dextroamphetamine, lisdexamphetamine)
  • aripiprazole
  • atomoxetine
  • atropine
  • azelastine
  • baclofen
  • barbiturates (e.g., butalbital, phenobarbital)
  • benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
  • benztropine
  • beta-adrenergic blockers (e.g., metoprolol, propranolol, sotalol)
  • brimonidine
  • buspirone
  • captopril
  • carbamazepine
  • carvedilol
  • chloral hydrate
  • chloroquine
  • cisapride
  • desvenlafaxine
  • dextromethorphan
  • disopyramide
  • domperidone
  • dopamine agonists (anti-Parkinson medications; e.g., amantadine, bromocriptine, levodopa, pramipexole, ropinirole)
  • doxorubicin
  • dronedarone
  • droperidol
  • efavirenz
  • ergot alkaloids (e.g., ergotamine, dihydroergotamine)
  • flavoxate
  • flecainide
  • gabapentin
  • glycopyrrolate
  • hydroxychloroquine
  • indapamide
  • ipratropium
  • lamotrigine
  • levetiracetam
  • lithium
  • lopinavir
  • macrolide antibiotics (e.g., clarithromycin, erythromycin)
  • magnesium sulfate
  • mefloquine
  • methadone
  • methylphenidate
  • metoclopramide
  • mexiletine
  • mifepristone
  • mirtazapine
  • monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, rasagiline, selegiline, tranylcypromine)
  • muscle relaxants (e.g., cyclobenzaprine, methocarbamol, orphenadrine)
  • narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone)
  • nefazodone
  • nilotinib
  • oxybutynin
  • perampanel
  • phenytoin
  • pimozide
  • porfimer
  • pregabalin
  • primaquine
  • procainamide
  • propafenone
  • pseudoephedrine
  • pyrimethamine
  • quinidine
  • quinine
  • quinolone antibiotics (e.g., ciprofloxacin, norfloxacin, ofloxacin)
  • St. John's wort
  • scopolamine
  • selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
  • serotonin antagonists (anti-emetic medications; e.g., granisetron, ondansetron)
  • sodium oxybate
  • sunitinib
  • tamoxifen
  • tamsulosin
  • tapentadol
  • tetrabenazine
  • tiotropium
  • tolterodine
  • topiramate
  • tramadol
  • trazodone
  • tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
  • "triptan" migraine medications (e.g., eletriptan, sumatriptan)
  • tryptophan
  • umeclidinium
  • vandetanib
  • vemurafenib
  • venlafaxine
  • zopiclone
  • zolpidem

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.