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Tasmar Side Effects

Generic Name: tolcapone

Note: This page contains side effects data for the generic drug tolcapone. It is possible that some of the dosage forms included below may not apply to the brand name Tasmar.

In Summary

Common side effects of Tasmar include: diarrhea, dyskinesia, insomnia, nausea, orthostatic hypotension, vomiting, confusion, dizziness, dystonia, headache, muscle cramps, anorexia, and increased dream activity. Other side effects include: syncope, abdominal pain, constipation, falling, fatigue, diaphoresis, urine discoloration, and xerostomia. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to tolcapone: oral tablet

As well as its needed effects, tolcapone (the active ingredient contained in Tasmar) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking tolcapone, check with your doctor immediately:

Incidence not known:
  • Dark urine
  • itching
  • light-colored stools
  • loss of appetite
  • nausea (continuing)
  • tenderness in upper right part of abdomen
  • unusual drowsiness, dullness, or feeling sluggish
  • unusual tiredness or weakness
  • yellow eyes or skin

Severity: Moderate

If any of the following side effects occur while taking tolcapone, check with your doctor or nurse as soon as possible:

More common:
  • Abdominal pain
  • cough
  • diarrhea
  • dizziness
  • dizziness or lightheadedness when getting up from a lying or sitting position
  • drowsiness
  • fainting
  • fever
  • hallucinations (seeing, hearing, or feeling things that are not there)
  • headache
  • nasal congestion (stuffy nose)
  • nausea
  • runny nose
  • sneezing
  • sore throat
  • trouble in sleeping
  • twitching, twisting, or other unusual body movements
  • vomiting
Less common:
  • Absence of or decrease in body movement
  • blood in urine
  • chest pain
  • chills
  • confusion
  • falling
  • general feeling of discomfort or illness
  • hyperactivity
  • loss of balance control
  • muscle pain
  • troubled breathing
  • Agitation
  • bloody or cloudy urine
  • burning of feet
  • burning, prickling, or tingling sensations
  • chest discomfort
  • difficult or painful urination
  • difficulty in thinking or concentrating
  • frequent urge to urinate
  • irritability
  • joint pain, redness, or swelling
  • low blood pressure
  • muscle cramps
  • neck pain
  • stiffness

Minor Side Effects

Some tolcapone side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Constipation
  • dryness of mouth
  • excessive dreaming
  • increased sweating
Less common:
  • Bleeding
  • difficulty in sleeping
  • excessive muscle tone
  • fever
  • heartburn
  • gas
  • muscle stiffness
  • muscle tension or tightness
  • trouble in holding or releasing urine

Side Effects: Post Treatment

After you stop taking this drug, it is possible that you may still experience side effects that need medical attention. If you notice any of the following side effects check with your doctor immediately:

  • Confusion
  • fever
  • muscle rigidity

For Healthcare Professionals

Applies to tolcapone: oral tablet


In general, tolcapone (the active ingredient contained in Tasmar) was well tolerated in clinical trials with most adverse events being mild to moderate in severity. Dyskinesia and other dopaminergic-related effects were the most frequently reported adverse events in patients with motor fluctuations. Diarrhea was the most common nondopaminergic adverse event, occurring in up to 26% of patients who received tolcapone, and necessitating discontinuation of treatment in approximately 5% to 10% of patients.[Ref]


Hepatic side effects have included severe liver damage, including fulminant liver failure resulting in death. Three cases of fatal fulminant hepatic failure have been reported from more than 40,000 patient years of worldwide use. Increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) have also been reported.[Ref]


Gastrointestinal side effects have included nausea (30% to 35%), anorexia (19% to 23%), diarrhea (16% to 18%), vomiting (8% to 10%), constipation (6% to 8%), xerostomia (5% to 6%), abdominal pain (5% to 6%), dyspepsia (3% to 4%), flatulence (2% to 4%), and dry mouth.[Ref]


Musculoskeletal side effects have included dystonia (19% to 22%), muscle cramps (17% to 18%), stiffness (2%), arthritis (1% to 2%), and hypertonia (1%).[Ref]


Respiratory side effects have included upper respiratory tract infection (5% to 7%), dyspnea (3%), and sinus congestion (1% to 2%).[Ref]


Genitourinary side effects have included urine discoloration (2% to 7%), urinary tract infection (5%), and micturition disorder (1% to 2%).[Ref]


Cardiovascular side effects have included chest pain (1% to 3%), hypotension (2%), chest discomfort (1% to 2%), and orthostatic symptoms.[Ref]


Dermatologic side effects have included dermal bleeding (1%), alopecia (1%), and increased sweating. At least one case of vitiligo has also been reported.[Ref]

A case report of vitiligo has been reported in a 50-year-old man with Parkinson's disease one week after the start of therapy with tolcapone 300 mg per day.[Ref]


Oncologic side effects have included tumors of the skin (1%) and tumors of the uterus (1%).[Ref]


Ocular side effects have included cataracts (1%) and inflamed eyes (1%).[Ref]

Nervous system

Nervous system side effects have included dyskinesia (42% to 51%), sleep disorder (24% to 25%), excessive dreaming (16% to 21%), somnolence (14% to 18%), orthostatic complaints (17%), dizziness (6% to 13%), confusion (10% to 11%), headache (10% to 11%), hallucination (8% to 10%), syncope (4% to 5%), hyperkinesia (2% to 3%), paresthesia (1% to 3%), hypokinesia (1% to 3%), loss of balance (2% to 3%), mental deficiency (1%), agitation (1%), hyperactivity (1%), and neuroleptic malignant-like syndrome. Akathisia, insomnia and sleep disturbances have also been reported.[Ref]

The neuroleptic malignant-like syndrome was reported in an elderly patient. It was caused by abrupt withdrawal of tolcapone.[Ref]


Other side effects have included fatigue (3% to 7%), falling (4% to 6%), increased sweating (4% to 7%), influenza (3% to 4%), neck pain (2%), burning (1% to 2%), irritability (1%), malaise (1%), panic reaction (1%), euphoria (1%), and fever (1%).[Ref]


1. Olanow CW, Watkins PB "Tolcapone: An Efficacy and Safety Review (2007)." Clin Neuropharmacol 30 (2007): 287-294

2. "Product Information. Tasmar (tolcapone)." Roche Laboratories, Nutley, NJ.

3. Dingemanse J "Issues important for rational COMT inhibition." Neurology 55(11 Suppl 4) (2000): S24-7; discussion S28-32

4. Hanson MR, Galvez-Jimenez N "Catechol-O-methyltransferase inhibitors in the management of Parkinson's disease." Semin Neurol 21 (2001): 15-22

5. Sabate M, Bosch A, Pedros C, Figueras A "Vitiligo associated with tolcapone and levodopa in a patient with Parkinson's disease." Ann Pharmacother 33 (1999): 1228-9

6. Iwuagwu CU, Riley D, Bonomo RA "Neuroleptic malignant-like syndrome in an elderly patient caused by abrupt withdrawal of tolcapone, a catechol-O-methyl transferase inhibitor." Am J Med 108 (2000): 517-8

It is possible that some side effects of Tasmar may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.