See also Warning section.
Drowsiness, trouble sleeping, tiredness, dizziness, nausea, and vomiting may occur. If any of these effects persist or worsen, 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 your doctor has prescribed this medication because he or she 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 any of these unlikely but serious side effects occur: signs of increased prolactin hormone (such as enlarged breasts, abnormal breast milk production, decreased sexual ability, a change in menstrual cycle).
Seek immediate medical attention if you have any of these rare but serious (possibly fatal) side effects: fast/irregular heartbeat, severe dizziness, fainting.
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, seek immediate medical attention 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.