Tolcapone
Tolcapone is an add-on medicine taken with levodopa/carbidopa to treat the signs and symptoms of Parkinson's disease, and it carries a serious liver warning.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 3 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Tolcapone (Tasmar) is an add-on to levodopa/carbidopa for Parkinson's disease that blocks COMT, an enzyme that breaks down levodopa, keeping levodopa levels steadier and easing symptom fluctuations; on the market since about 1998 and available as a generic, it is a reserve option for when other add-ons have failed or are not suitable. Many people notice more dyskinesia (extra writhing movements) as levodopa works harder, along with nausea, diarrhea or vivid dreams. The boxed warning is rare but potentially fatal liver failure, so expect frequent liver blood tests, especially in the first 6 months, and report yellow skin or eyes, dark urine or clay-colored stools right away.
Clinical pearls
- With no clear benefit within 3 weeks, tolcapone should be stopped, since its liver risk is only justified when it helps.
- Take the first dose alongside your first levodopa/carbidopa dose of the day, then again about 6 and 12 hours later.
- Tolcapone can cause sudden sleep without warning, even at the wheel, so do not drive if you have dozed off unexpectedly.
- Older MAO inhibitor antidepressants like phenelzine and tranylcypromine should generally not be combined with it, but selegiline can be.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Tolcapone can cause rare but potentially fatal liver failure. It is usually used only when other add-on therapies are not working or are not suitable.
- It should not be started if you have liver disease or abnormal liver tests.
- Liver blood tests are recommended at baseline and about every 2 to 4 weeks for the first 6 months.
- It should be stopped if liver tests rise above 2 times the upper limit of normal or symptoms of liver trouble appear.
- If you show no clear benefit within 3 weeks, it should be stopped.
- If stopped for liver injury, it should not ordinarily be restarted.
Watch for jaundice, clay-colored stools, dark urine, itching, fatigue, loss of appetite, lethargy, persistent nausea, and upper right belly tenderness.
Patient information guide A plain-language walkthrough of Tolcapone, written from its FDA label.
What Tolcapone is used for
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Tolcapone is used only as an add-on treatment for Parkinson's disease.
- Tasmar (oral tablet): add-on to levodopa and carbidopa for the signs and symptoms of idiopathic Parkinson's disease.
- Tolcapone tablets (oral): the same use.
- It is usually reserved for people with symptom fluctuations who are not doing well on, or are not candidates for, other add-on therapies.
How Tolcapone works
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Tolcapone is a selective, reversible blocker of COMT, an enzyme that breaks down levodopa. When taken with levodopa and carbidopa, levodopa levels stay steadier in the blood.
This is believed to give more constant stimulation in the brain, which improves Parkinson's symptoms. It can also increase levodopa side effects, sometimes needing a lower levodopa dose.
Tolcapone dosage
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Tolcapone is taken by mouth three times a day. The first dose of the day goes with your first levodopa/carbidopa dose, and the others follow about 6 and 12 hours later.
- You can take it with or without food.
- Your doctor may lower your levodopa dose.
- If you show no clear benefit within 3 weeks, it should be stopped.
Dosing details from the FDA-approved label
From the Tolcapone prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Parkinson's disease patients on l-dopa/carbidopa with symptom fluctuations (initial and recommended dose)
- The initial dose of TASMAR is always 100 mg three times per day
- The recommended daily dose is also 100 mg tid
- The first dose of the day was taken together with the first dose of the day of levodopa/carbidopa, and subsequent doses approximately 6 and 12 hours later in clinical trials
- May be taken with or without food; discontinue if no substantial clinical benefit within 3 weeks of initiation
- Patients needing more effect (200 mg tid dose)
- 200 mg tid, used only if the anticipated incremental clinical benefit is justified
- Elevations in ALT occurred more frequently at 200 mg tid; discontinue if no expected incremental benefit after a total of 3 weeks of treatment (regardless of dose)
- Patients on levodopa daily dose >600 mg or with moderate or severe dyskinesias before treatment
- Reductions in daily levodopa dose may be necessary
- In clinical trials the average reduction was about 30% in patients requiring a reduction
- Greater than 70% of patients with levodopa doses above 600 mg daily required such a reduction
- Patients with impaired hepatic function
- Therapy should not be initiated in any patient with liver disease or two SGPT/ALT or SGOT/AST values greater than the upper limit of normal
- Patients with impaired renal function
- No dose adjustment recommended for mild to moderate renal impairment
- Patients with severe renal impairment should be treated with caution
- Safety not examined in subjects with creatinine clearance less than 25 mL/min
Read the label’s full dosing text
DOSAGE AND ADMINISTRATION Because of the risk of potentially fatal, acute fulminant liver failure, tolcapone tablets should ordinarily be used in patients with Parkinson's disease on l-dopa/carbidopa who are experiencing symptom fluctuations and are not responding satisfactorily to or are not appropriate candidates for other adjunctive therapies (see INDICATIONS AND USAGE and DOSAGE AND ADMINISTRATION sections). BECAUSE OF THE RISK OF LIVER INJURY AND BECAUSE TOLCAPONE TABLETS WHEN IT IS EFFECTIVE PROVIDES AN OBSERVABLE SYMPTOMATIC BENEFIT, THE PATIENT WHO FAILS TO SHOW SUBSTANTIAL CLINICAL BENEFIT WITHIN 3 WEEKS OF INITIATION OF TREATMENT, SHOULD BE WITHDRAWN FROM TOLCAPONE TABLETS Tolcapone tablets therapy should not be initiated if the patient exhibits clinical evidence of liver disease or two SGPT/ALT or SGOT/AST values greater than the upper limit of normal. Patients with severe dyskinesia or dystonia should be treated with caution (see PRECAUTIONS : Rhabdomyolysis). Patients who develop evidence of hepatocellular injury while on tolcapone tablets and are withdrawn from the drug for any reason may be at increased risk for liver injury if tolcapone tablets is reintroduced. These patients should not ordinarily be considered for retreatment with tolcapone tablets. Only prescribe tolcapone tablets for patients taking concomitant carbidopa levodopa therapy. The initial dose of tolcapone tablets is always 100 mg three times per day. The recommended daily dose of tolcapone tablets is also 100 mg tid. In clinical trials, elevations in ALT occurred more frequently at the dose of 200 mg tid. While it is unknown whether the risk of acute fulminant liver failure is increased at the 200-mg dose, it would be prudent to use 200 mg only if the anticipated incremental clinical benefit is justified (see BOXED WARNING , WARNINGS , PRECAUTIONS : Laboratory Tests ). If a patient fails to show the expected incremental benefit on the 200-mg dose after a total of 3 weeks of treatment (regardless of dose), tolcapone tablets should be discontinued. In clinical trials, the first dose of the day of tolcapone tablets was always taken together with the first dose of the day of levodopa/carbidopa, and the subsequent doses of tolcapone tablets were given approximately 6 and 12 hours later.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Tolcapone side effects
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Common side effects seen in trials include:
Common side effects
- Dyskinesia (uncontrolled, writhing movements)
- Nausea
- Diarrhea
- Loss of appetite
- Sleep problems and vivid dreams
- Vomiting
- Orange or dark urine discoloration
- Drowsiness
- Dystonia (muscle spasms)
- Increased sweating
When to get medical help
- Call your doctor right away if you notice yellowing of the skin or eyes (jaundice), dark urine, or clay-colored stools.
- Report persistent nausea, unusual tiredness, lethargy, loss of appetite, itching, or pain in the upper right belly. These can be signs of liver injury.
- Tell your doctor if you suddenly fall asleep during daily activities, or have significant daytime sleepiness.
- Report hallucinations or confusion.
- Report severe or worsening muscle problems or movements, or high fever with confusion.
- Report severe or ongoing diarrhea.
Diarrhea was the most common reason for stopping. Contact your doctor right away for signs of liver problems, sudden sleep episodes, or hallucinations.
Tolcapone warnings and precautions
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- Liver failure: rare but can be fatal. Regular blood tests are needed.
- Sudden sleep: some people fall asleep without warning, even while driving.
- Dyskinesia and dystonia: use with caution if severe.
- Rhabdomyolysis and high fever with confusion: a history of these is a reason not to use it.
Tolcapone interactions
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Tell your prescriber about every medicine you use.
- Non-selective MAO inhibitors (phenelzine, tranylcypromine): ordinarily avoid, since both block catecholamine breakdown.
- Selegiline (an MAO-B inhibitor): can be used together.
- Warfarin: clotting tests should be monitored.
- Desipramine: use caution.
- Methyldopa, dobutamine, apomorphine, isoproterenol: may need a dose reduction.
Interactions listed in the FDA-approved label
From the Tolcapone prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Highly protein-bound drugs (warfarin, phenytoin, tolbutamide, digitoxin): In vitro, tolcapone at 50 mcg/mL did not displace other highly protein-bound drugs from their binding sites at therapeutic concentrations.
- Drugs metabolized by COMT (α-methyldopa, dobutamine, apomorphine, isoproterenol): Tolcapone may influence the pharmacokinetics of drugs metabolized by COMT; effects on these drugs have not been evaluated, and no effect was seen on carbidopa. A dose reduction of such compounds should be considered when co-administered with tolcapone.
- Warfarin: Tolcapone has affinity for cytochrome P450 2C9 in vitro and may interfere with drugs cleared by this pathway, but clinical information on the combination is limited. Coagulation parameters should be monitored when the two drugs are co-administered.
- Tolbutamide: In an in vivo study tolcapone did not change the pharmacokinetics of tolbutamide; clinically relevant CYP 2C9 interactions appear unlikely.
- Ephedrine: Tolcapone did not influence the effect of ephedrine on hemodynamic parameters or plasma catecholamine levels and did not alter its tolerability. These drugs can be co-administered.
- Desipramine: With levodopa/carbidopa and desipramine there was no significant change in blood pressure, pulse rate or desipramine concentrations, but the frequency of adverse events increased slightly, as predictable from each drug. Caution should be exercised when desipramine is given to Parkinson's disease patients treated with tolcapone and levodopa/carbidopa.
- Selegiline (selective MAO-B inhibitor): Patients receiving tolcapone/levodopa reported a similar adverse event profile whether or not they also took selegiline.
- CYP substrates (CYP 2A6, 1A2, 3A4, 2C19, 2D6: caffeine, midazolam, terfenadine, cyclosporine, S-mephenytoin): No relevant interactions were observed in vitro.
Read the label’s full interactions text
Drug Interactions: See PRECAUTIONS: Drug Interactions .
Drug Interactions: Protein Binding: Although tolcapone is highly protein bound, in vitro studies have shown that tolcapone at a concentration of 50 mcg/mL did not displace other highly protein-bound drugs from their binding sites at therapeutic concentrations. The experiments included warfarin (0.5 to 7.2 mcg/mL), phenytoin (4.0 to 38.7 mcg/mL), tolbutamide (24.5 to 96.1 mcg/mL) and digitoxin (9.0 to 27.0 mcg/mL). Drugs Metabolized by Catechol-O-Methyltransferase (COMT): Tolcapone may influence the pharmacokinetics of drugs metabolized by COMT. However, no effects were seen on the pharmacokinetics of the COMT substrate carbidopa. The effect of tolcapone on the pharmacokinetics of other drugs of this class such as α-methyldopa, dobutamine, apomorphine, and isoproterenol has not been evaluated. A dose reduction of such compounds should be considered when they are co-administered with tolcapone. Effect of Tolcapone on the Metabolism of Other Drugs: In vitro experiments have been performed to assess the potential of tolcapone to interact with isoenzymes of cytochrome P450 (CYP). No relevant interactions with substrates for CYP 2A6 (warfarin), CYP 1A2 (caffeine), CYP 3A4 (midazolam, terfenadine, cyclosporine), CYP 2C19 (S-mephenytoin) and CYP 2D6 (desipramine) were observed in vitro. The absence of an interaction with desipramine, a drug metabolized by cytochrome P450 2D6, was also confirmed in an in vivo study where tolcapone did not change the pharmacokinetics of desipramine. Due to its affinity to cytochrome P450 2C9 in vitro, tolcapone may interfere with drugs, whose clearance is dependent on this metabolic pathway, such as tolbutamide and warfarin. However, in an in vivo interaction study, tolcapone did not change the pharmacokinetics of tolbutamide. Therefore, clinically relevant interactions involving cytochrome P450 2C9 appear unlikely.
Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Tolcapone
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- Do not use with liver disease or abnormal liver tests.
- Do not use if you stopped it before for liver injury from it.
- Do not use with a history of nontraumatic rhabdomyolysis or high fever with confusion linked to medication.
- Do not use if allergic to it.
- No dose change is recommended for mild to moderate kidney impairment.
- Mention sleep disorders and sedating medicines.
Tolcapone overdose
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Nausea, vomiting, and dizziness were seen at very high doses, especially along with levodopa/carbidopa. The label advises hospitalization and general supportive care. Dialysis is unlikely to help.
What Tolcapone does in the body
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Tolcapone reversibly blocks COMT activity in red blood cells, and the effect follows its blood levels. It also sharply lowers levels of 3-OMD, a breakdown product of levodopa, when taken with levodopa/carbidopa.
How your body processes Tolcapone
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Tolcapone is absorbed quickly, peaking in about 2 hours. Food slightly lowers absorption but it can still be taken with or without food. Its half-life is 2 to 3 hours. It is almost entirely metabolized, mainly by glucuronidation, and cleared through urine and feces. With levodopa/carbidopa, it roughly doubles levodopa exposure.
How to store Tolcapone
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Store in tight containers at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) .
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Tolcapone
58 supplements and herbal products have documented interactions with Tolcapone in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 4
- Moderate · 45
- Minor · 9
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Tolcapone: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Tolcapone — the kind of thing our pharmacy team would talk through with you at the counter.
What is tolcapone for?
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How do I take it?
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Why do I need blood tests?
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What side effects should I expect?
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Is it safe to drive?
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What happens if it is not working?
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Is Tolcapone available over the counter?
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When was Tolcapone first available?
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Who makes Tolcapone?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Tolcapone on HelloPharmacist
Tolcapone forms and strengths (how it comes)
Tolcapone is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Tolcapone inactive ingredients by manufacturer.
Tablet
How this form is used
- Tasmar is used as an add-on to levodopa and carbidopa for idiopathic Parkinson's disease.
- Tolcapone tablets are used as an add-on to levodopa and carbidopa for idiopathic Parkinson's disease.
- Tasmar may be taken with or without food.
- Tolcapone tablets may be taken with or without food.
- Tasmar and Tolcapone tablets are taken three times daily, with the first dose given together with the first levodopa/carbidopa dose.
- Tasmar and Tolcapone tablets can be combined with immediate- or sustained-release levodopa/carbidopa.
Tolcapone on the U.S. market: products, makers and brands
How Tolcapone appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
3 companies list 3 Tolcapone product records with the FDA, mostly as tablet; the earliest marketing or approval year on record is 1998. Brand names on the directory include Tasmar; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (3) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Compare Tolcapone products
A representative set of FDA-listed product records for Tolcapone — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 100 mg | Oral | Bausch Health US LLC | NDA | View NDC → |
| 100 mg | Oral | Ingenus Pharmaceuticals, LLC | ANDA | View NDC → |
| 100 mg | Oral | Oceanside Pharmaceuticals | NDA AUTHORIZED GENERIC | View NDC → |
Showing 3 of 3 products — FDA National Drug Code Directory. See every product, package size and price: browse all 3 Tolcapone NDCs →
Tolcapone side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Tolcapone — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Tolcapone in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Tolcapone FDA approval history
How Tolcapone went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Tolcapone recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Tolcapone recalls since July 2021.
✅No Tolcapone recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 72937 1 dose form · 2 strengths
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Dose form (SCDF) Oral Tablet RxCUI 374153In current FDA listings
Look up RxCUI 72937 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Tolcapone supply and shortage status
Whether Tolcapone is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Tolcapone brand names
Tolcapone is sold under one brand name in the FDA directory — Tasmar. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Tolcapone: manufacturers and labelers
3 companies list Tolcapone products with the FDA. By number of product records, the largest are Bausch Health US LLC, Ingenus Pharmaceuticals, LLC, Oceanside Pharmaceuticals. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Tolcapone drug class (RxNorm)
Tolcapone belongs to the Catechol-O-Methyltransferase Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Tolcapone page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Oceanside Pharmaceuticals is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →