tolcapone at a glance
Medicine class
COMT inhibitor used to prolong levodopa’s effect.
Used with
Levodopa combined with benserazide or carbidopa; it does not work as Parkinson’s treatment on its own.
Food
May be taken with or without food.
Important monitoring
Regular liver-function blood tests are essential.
What is tolcapone used for?
Licensed use in the selected UK product:
Alongside levodopa/benserazide or levodopa/carbidopa for levodopa-responsive idiopathic Parkinson’s disease with motor fluctuations, after other COMT inhibitors have failed or were not tolerated.
It is not licensed as first-line adjunctive treatment or for use without levodopa.
How does tolcapone work?
Tolcapone reversibly blocks COMT, an enzyme that breaks down levodopa. This sustains levodopa exposure and can reduce wearing-off fluctuations.
tolcapone preparations and strengths
Tablet
Route: Oral
Strengths: 100 mg
How to take tolcapone
Use exactly as prescribed alongside the specified levodopa preparation.
Swallow the film-coated tablets whole with water; they taste bitter if broken or crushed.
The tablets may be taken with or without food.
Do not change or stop Parkinson’s treatments without advice from the prescribing team.
tolcapone side effects
Common or expected effects
- Involuntary movements or worsening dyskinesia
- Nausea, reduced appetite or diarrhoea
- Headache, dizziness or light-headedness on standing
- Sleep disturbance, drowsiness or vivid dreams
- Confusion or hallucinations
- Vomiting, abdominal discomfort, constipation or dry mouth
- Harmless yellow-orange urine discolouration
Get urgent medical advice
- Symptoms of liver injury, including jaundice, dark urine, persistent nausea, marked fatigue, itching or upper-right abdominal pain
- Fever, severe muscle stiffness and confusion, particularly after treatment changes
- Persistent or severe diarrhoea
- Sudden sleep episodes during driving or other hazardous activities
- New uncontrollable gambling, spending, eating or sexual urges
tolcapone in pregnancy
Human pregnancy data are inadequate. UK product information advises use only when the expected benefit justifies the potential fetal risk. Pregnancy or plans to conceive require specialist review; do not stop prescribed treatment without medical advice.
tolcapone while breastfeeding
Breastfeeding is not recommended during treatment because infant safety is unknown and animal studies found tolcapone in milk. Discuss feeding and treatment options with the specialist team.
tolcapone interactions
Important interactions include:
Levodopa combinations
Tolcapone increases levodopa exposure and may worsen dyskinesia, nausea, hallucinations, faintness or drowsiness.
Non-selective monoamine oxidase inhibitors
Concomitant use is contraindicated; combined MAO-A and MAO-B inhibition is treated as non-selective inhibition.
Warfarin
The interaction is insufficiently characterised, so coagulation measurements require closer monitoring.
Potent noradrenaline-reuptake inhibitors
Common questions about tolcapone
Answers are fully visible for fast scanning and source review.
Why is tolcapone not usually the first COMT inhibitor prescribed?
It carries a risk of rare, potentially fatal liver injury, so it is reserved for people who have not responded to or cannot tolerate other COMT inhibitors.
Can tolcapone be used without levodopa?
No. Its licensed role is alongside levodopa combined with benserazide or carbidopa.
Why are blood tests needed?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.