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Precautions and Warnings With Tolcapone

It is important to understand precautions and warnings with tolcapone before beginning treatment. For example, certain medical conditions, such as liver disease, lung problems, or any allergies, need to be reported to your healthcare provider before you start tolcapone. Other precautions and warnings with tolcapone include being aware that the drug can cause fatal liver failure, neuroleptic malignant syndrome, and drug interactions.

Tolcapone: What Should I Tell My Healthcare Provider?

You should talk with your healthcare provider prior to taking tolcapone (Tasmar®) if you have:
  • Liver disease, such as liver failure, cirrhosis, or hepatitis
  • Lung problems, such as asthma or chronic obstructive pulmonary disease (COPD)
  • Ever had severe muscle pain or the combination of a fever with confusion possibly related to any medication
  • Kidney disease, such as kidney failure (renal failure)
  • Any allergies, including allergies to foods, dyes, or preservatives.
Also, let your healthcare provider know if you are:
  • Pregnant or thinking of becoming pregnant
  • Breastfeeding.
Make sure to tell your healthcare provider about any medications you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Specific Precautions and Warnings With Tolcapone

Warnings and precautions to be aware of prior to taking tolcapone include the following:
  • The medication can cause fatal liver failure. In order to catch liver problems before they become dangerous, it is important to have regular liver monitoring. Your healthcare provider should check your liver enzymes before you start tolcapone, then every two to four weeks for the first six months, and then periodically thereafter as your healthcare provider deems necessary. This is done with a simple blood test. If at any time your liver enzymes increase to more than twice the upper limit of normal, you must stop taking tolcapone permanently.
  • If your liver enzymes are already elevated, or if you already had liver problems before taking tolcapone, you should not start taking this medication.
  • Tolcapone should always be used in combination with carbidopa-levodopa products (such as Sinemet®, Sinemet CR, or Parcopa®). The drug is not effective at treating Parkinson's disease when used alone.
  • Due to the risks of liver failure, only people who are experiencing symptom fluctuations (such as "wearing-off") while taking carbidopa-levodopa should take tolcapone. Also, this drug should only be taken if other Parkinson's disease treatment alternatives are not appropriate or have failed.
  • Let your healthcare provider know if you do not experience a noticeable benefit within three weeks of starting tolcapone, as this medication should only be continued if it is beneficial.
  • Stopping the drug too quickly can cause a dangerous condition known as neuroleptic malignant syndrome (NMS). Do not stop taking tolcapone without your healthcare provider's approval and supervision. Let your healthcare provider know if you develop any signs of NMS, such as:
    • A high fever
    • Irregular pulse or blood pressure
    • A fast heart rate (tachycardia)
    • Sweating
    • Stiff muscles
    • Confusion
    • Irregular heart rhythms (arrhythmias).
  • Tolcapone can cause diarrhea. Sometimes, it can be severe enough to require hospitalization. This diarrhea can occur at any time, not just when starting the medication.
  • Tolcapone can cause low blood pressure (hypotension). Be sure to let your healthcare provider know if you develop any signs of low blood pressure, such as lightheadedness, dizziness, or fainting.
  • The medication can cause hallucinations (seeing, hearing, or feeling things that are not there). Let your healthcare provider know if you develop hallucinations while taking tolcapone. Also, let your healthcare provider know of any other mental or behavioral changes.
  • Reports of falling asleep suddenly and without warning have been reported in people taking this medication. This can interfere with your daily life (for instance, if you fall asleep during conversations) and can be very dangerous (for example, if you fall asleep while driving). Let your healthcare provider know right away if you begin to experience this side effect.
  • Let your healthcare provider know if you develop severe muscle pain or weakness while taking tolcapone, as these may be signs of rhabdomyolysis, a dangerous condition involving muscle breakdown that can result in kidney damage.
  • Tolcapone can cause involuntary muscle movements called dyskinesia. Although not typically dangerous, dyskinesia can be quite disturbing and intolerable. If you develop dyskinesia while taking the drug, your healthcare provider may need to decrease your tolcapone dosage, or you may need to stop taking it altogether.
  • If you have kidney problems or lung problems, check with your healthcare provider before taking tolcapone. In some cases, this medication may not be the best choice for you.


  • Intense, unusual urges have been reported in people taking Parkinson's disease medications. Examples include an intense desire to gamble or to engage in risky sexual behavior. Let your healthcare provider know right away if you experience any of these urges.
  • People with Parkinson's disease have an increased risk for melanoma (a type of skin cancer). At this time, it is not clear if this is caused by Parkinson's disease medications or other factors. It is a good idea to have regular skin checks to monitor for this problem. 


  • Tolcapone can potentially interact with several medications (see Drug Interactions With Tolcapone).
  • Tolcapone is considered a pregnancy Category C medication. This means it may not be safe for use during pregnancy, although the full risks are not known (see Tasmar and Pregnancy).
  • It is not known if tolcapone passes through breast milk. Therefore, if you are breastfeeding or plan to start, discuss this with your healthcare provider prior to taking the drug (see Tasmar and Breastfeeding).
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Tolcapone Drug Information

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