Tetrabenazine is used to decrease the uncontrollable movements (chorea) caused by Huntington's disease. However, it is not a cure for the disease. Reducing the chorea will help you take part in more of your normal daily activities. This medication is thought to work by decreasing the amount of certain natural substances in the brain (monoamines such as dopamine, serotonin, and norepinephrine), which are involved with nerve and muscle function. Tetrabenazine belongs to a class of drugs called monoamine depletors.

Read the Medication Guide provided by your pharmacist before you start using tetrabenazine and each time you get a refill. If you have any questions, consult your doctor or pharmacist.

Take this medication by mouth with or without food as directed by your doctor, usually once a day in the morning when you first start treatment. Your doctor may gradually increase your dose to 2 or 3 times a day over several weeks. A slow increase in your dose will help your doctor find the best dose for you while keeping side effects as low as possible.

The dosage is based on your medical condition, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

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

If you stop taking this drug for several days, then start taking it again, you may need to slowly increase your dose until you reach the regular dose you had been taking. Follow your doctor's directions on how to restart treatment.

Tell your doctor if your uncontrolled movements do not get better or if they get worse.

See also Warning section.

Drowsiness, trouble sleeping, tiredness, dizziness, nausea, and vomiting may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. Your doctor may need to adjust your dose to reduce these side effects.

To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Sometimes tetrabenazine can cause side effects that are similar to the symptoms of worsening Huntington's disease. Your doctor may need to adjust your dose to see if these side effects are due to the drug or to the disease. Tell your doctor right away if any of these serious side effects occur:

• mental/mood changes (such as new/worsening depression, suicidal thoughts/attempts, problems with thinking)
• Parkinson's disease symptoms (such as shaking/tremors, slowed movement, loss of balance)
• trouble swallowing
• restlessness

Tell your doctor right away if you have any serious side effects, including:

• signs of increased prolactin hormone (such as enlarged breasts, abnormal breast milk production, decreased sexual ability, a change in menstrual cycle)

This medication may rarely cause a very serious condition called neuroleptic malignant syndrome (NMS). Get medical help right away if you have any of the following symptoms:

• fever
• muscle stiffness/pain/tenderness/weakness
• severe tiredness
• severe confusion
• sweating
• fast/irregular heartbeat
• dark urine
• signs of kidney problems (such as change in the amount of urine)

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

See also Warning section.

Before taking tetrabenazine, tell your doctor or pharmacist if you are allergic to it; or to deutetrabenazine; 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:

• breast cancer
• liver problems
• certain heart problems (fast/slow/irregular heartbeat, QT prolongation in the EKG)

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

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

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

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.

Some products that may interact with this drug are:

• valbenazine

Taking MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Do not take any MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before and after treatment with this medication. Ask your doctor when to start or stop taking this medication.

Tetrabenazine is very similar to deutetrabenazine. Do not use medications containing deutetrabenazine while using tetrabenazine.

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: muscle stiffness/pain, fixed upward position of the eyeballs, sweating, dizziness, severe drowsiness.

Do not share this medication with others.

Lab and/or medical tests may 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.