Tetrabenazine belongs to the class of medications called monoamine depleting agents. It is used to reduce uncontrolled movement that is seen in Huntington's chorea, tardive dyskinesia, hemiballismus, senile chorea, tic and Tourette's syndrome. This medication works in the brain, interfering with the storage of some of the chemicals that are linked to movement disorders, such as serotonin and dopamine.

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.

The recommended starting dose of tetrabenazine for adults is 12.5 mg (1/2 a tablet) 2 to 3 times daily. If this is tolerated, the dose may be gradually increased to 25 mg taken 3 times a day.

Usually, improvement is seen after a week at the maximum dose that side effects are not a problem. If this is not the case, this medication may not be appropriate for you.

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. Missing doses over several days may require you to restart with a lower dose.

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

Do not take tetrabenazine if you:

• are allergic to tetrabenazine or any ingredients of the medication
• have untreated or poorly treated signs of depression (e.g., poor concentration, changes in sleep, decreased interest in activities)
• have had depression or are currently being treated for depression, unless you are under the care of a psychiatrist experienced with your condition and the medication tetrabenazine
• have taken a monoamine oxidase inhibitor (MAOI) within the last 14 days
• plan to start taking a MAOI in the next 14 days
• have reduced liver function
• are taking a medication for high blood pressure called reserpine
• you are currently experiencing thoughts of suicide

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.

• difficulty sleeping
• dizziness
• drooling
• drowsiness
• fatigue
• increased appetite
• nausea
• severe dizziness when standing or sitting from a lying position
• stomach pain
• vomiting
• weakness
• 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:

• agitation
• anxiety
• confusion, disorientation
• difficulty swallowing
• increasing restlessness
• irritability
• low blood pressure
• nervousness
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of parkinsonism (e.g., tremor, muscle stiffness, difficulty starting movement, decrease in facial expressions, speech problems)

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

• signs of heartbeat problems (e.g., dizziness, sensation of a pounding or irregular heartbeat, fainting or seizures)
• signs of neuroleptic malignant syndrome (e.g., high fever, muscle stiffness, confusion, profuse sweating, racing or irregular heartbeat)
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• thoughts of suicide or self-harm

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: Tetrabenazine may cause a heart rhythm problem called QT prolongation. If you have a history of QT prolongation, slow or irregular heartbeat, irregular heart rhythm, heart failure, heart attack, heart disease, taking other medications known to cause QT prolongation, or a family history of sudden cardiac death at less than 50 years of age, discuss with your doctor how this medication may affect your medical condition, or how your medical condition may affect the dosing and effectiveness of this medication. Your doctor will perform tests at regular intervals to monitor for any changes in your heart rhythm.

Alcohol and other medications that cause drowsiness: Do not combine this medication with alcohol or other medications that cause drowsiness or suppress breathing (e.g., antidepressants, sleeping pills, anxiety medications). These side effects are additive and can cause life-threatening effects.

Depression: Tetrabenazine may cause depression. 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. The symptoms of depression may be as severe as thinking about hurting yourself of others. If you experience these side effects or notice them in a family member who is taking this medication, contact your doctor immediately.

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.

Drowsiness/reduced alertness: Tetrabenazine may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid these and other hazardous tasks until you have determined how this medication affects you.

Low blood pressure: Tetrabenazine may cause a decrease in blood pressure causing dizziness and fainting, especially when getting up from a sitting or lying position. Get up slowly from a sitting or lying position to avoid dizziness, fainting, or falling.

Neuroleptic malignant syndrome (NMS): Like other medications that affect chemical messengers in the brain, tetrabenazine can cause a potentially fatal syndrome known as neuroleptic malignant syndrome (NMS). If you notice the symptoms of NMS such as high fever, muscle stiffness, confusion or loss of consciousness, sweating, racing or irregular heartbeat, or fainting, get immediate medical attention.

Parkinsonism: Tetrabenazine works to reduce uncontrolled movement. Some people taking tetrabenazine have experienced tremor or stiff muscles with difficulty starting movement, a condition that mimics Parkinson's disease. If you experience these signs, contact your doctor as soon as possible.

Pregnancy: 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.

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

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

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

• abiraterone
• alcohol
• amiodarone
• antihistamines (e.g., azelastine, cetirizine, diphenhydramine, hydroxyzine)
• antipsychotics (e.g., aripiprazole, cariprazine, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• barbiturates (e.g., butalbital, phenobarbital)
• benzodiazepines (e.g., alprazolam, clobazam, diazepam, lorazepam)
• brimonidine
• buprenorphine
• butorphanol
• cannabis
• chloral hydrate
• cinacalcet
• clonidine
• darifenacin
• darunavir
• diphenoxylate
• disopyramide
• dronedarone
• duloxetine
• efavirenz
• entacapone
• esketamine
• fluoxetine
• general anesthetics (medications to put you to sleep for surgery)
• kava kava
• ketamine
• ketotifen
• lamotrigine
• lemborexant
• levodopa
• linezolid
• magnesium sulfate
• methylene blue
• metoclopramide
• mifepristone
• mirabegron
• mirtazapine
• monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
• muscle relaxants (e.g., baclofen, cyclobenzaprine, methocarbamol, orphenadrine)
• nabilone
• olopatadine
• opioids (e.g., codeine, fentanyl, hydromorphone, methadone, morphine, tramadol)
• paroxetine
• peginterferon alfa-2b
• perampanel
• pizotifen
• pomalidomide
• pramipexole
• pregabalin
• procainamide
• propafenone
• quinine
• ropinirole
• rotigotine
• seizure medications (e.g., gabapentin, levetiracetam, phenytoin, rufinamide, topiramate)
• sodium oxybate
• sotalol
• terbinafine
• tipranavir
• tizanidine
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, desipramine, nortriptyline)
• valerian
• 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.