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Tolcapone for Parkinson's disease


Tolcapone will be recommended for you by a specialist doctor who will continue to check on your progress.

The usual dose is one 100 mg tablet three times daily.

Tolcapone can cause liver problems. You should tell your doctor immediately if you lose your appetite, feel sick or have pain in your tummy (abdomen), develop dark-coloured urine or itchy skin, or feel generally tired or unwell.

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About tolcapone

Type of medicine

A dopaminergic medicine called a catechol-O-methyltransferase inhibitor

Used for

Parkinson's disease

Also called


Available as


Parkinson's disease affects the way your brain co-ordinates the movements of your muscles. A number of cells in a small part of your brain called the substantia nigra become damaged and die. These brain cells pass messages down nerves in the spinal cord by producing a substance called dopamine, and it is these messages which control the muscles of the body. As the cells in the brain are damaged, the amount of dopamine that is produced is reduced. A combination of the reduction of cells and a low level of dopamine in the cells in this part of the brain, causes nerve messages to the muscles to become slowed and abnormal. This produces the main symptoms of Parkinson's disease, which are stiffness, shaking (tremor), and slowness of movement.

You will already be taking a medicine called either co-beneldopa or co-careldopa. These contain levodopa which helps relieve the symptoms of Parkinson's disease. Levodopa is converted into dopamine and this increases the level of dopamine in your brain.

Tolcapone works by increasing the effectiveness of the levodopa you are taking in co-beneldopa or co-careldopa. It is prescribed for people who have had Parkinson's disease for a while and whose symptoms deteriorate between medicine doses. It may be recommended for you if other, similar medicines, are not suitable for you. It will be prescribed for you by a specialist doctor.

Before taking tolcapone

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking tolcapone it is important that your doctor knows:

  • If you are pregnant or breastfeeding.

  • If you have a problem with the way your kidneys work, or a problem with the way your liver works.

  • If you have uncontrolled muscle movements called dyskinesia.

  • If you have been told you have a tumour on your adrenal gland, or if you have ever had a condition affecting your muscles, called rhabdomyolysis, or a reaction to an antipsychotic medicine, called neuroleptic malignant syndrome, or an extremely high body temperature called hyperthermia. These are all very rare conditions.

  • If you are taking or using any other medicines. It is especially important that your doctor knows if you have recently taken an antidepressant known as a monoamine-oxidase inhibitor (MAOI). You should also tell your doctor if you are taking any medicines which you have bought without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

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How to take tolcapone

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack and any additional information your doctor has given to you. These will give you more information about tolcapone, and will also provide you with a full list of side-effects which you could experience from taking it.

  • Take the tablets exactly as your doctor tells you to. It is usual to take one tablet three times daily, although the dose may be increased in some people to two tablets three times daily. Take your first dose of each day at the same time as your first dose of co-careldopa/co-beneldopa, and then leave six hours before you take your next dose, and a further six hours before you take the third dose. Swallow the tablets whole, without breaking, chewing or crushing them. This is because the tablets are specially coated so that you do not taste the medicine which has a bitter taste.

  • You can take tolcapone either before or after meals.

  • When you first start taking tolcapone, your doctor may need to adjust the doses of your other medicines. This is to help reduce any side-effects caused by these tablets increasing the effectiveness of your usual dose of levodopa.

  • If you forget to take a tablet at the usual time, take it as soon as you remember. Try to take the correct number of doses each day and remember to leave six hours between each dose. Do not take two doses together to make up for a forgotten dose.

Getting the most from your treatment

  • It is important that you keep your regular appointments with your doctor and clinic. This is so your doctor can check on your progress. Tolcapone can sometimes cause liver problems, so you will need to have regular blood tests to make sure the tablets are not causing any problems to the way your liver works.

  • Tolcapone may cause your urine to become more yellow in colour. This is harmless and is nothing to worry about. If, however, your urine becomes dark in colour, and you also have other symptoms, please let your doctor know about this.

  • Stay as active as possible and exercise regularly as much as you are able. You may walk more slowly than before, but a daily walk is good exercise and may help to loosen up stiff muscles.

  • If you are a driver you should tell the DVLA and your insurance company if you have Parkinson's disease.

  • Keep taking the tablets until your doctor tells you otherwise. Stopping suddenly can cause problems and your doctor will want you to reduce your dose gradually if you need to stop treatment.

  • Sometimes people taking medicines for Parkinson's disease can feel very sleepy during the day. Some people have even fallen asleep suddenly without much warning of being tired. If this happens to you, do not drive and do not use tools or machines, and discuss it with your doctor at your next appointment.

  • Some people taking medicines for Parkinson's disease can experience problems with impulsive types of behaviour. If you notice any changes in your behaviour, such as an increased desire to gamble, binge eat, or spend excessively, or an increased sex drive, you must let your doctor know as soon as possible.

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Can tolcapone cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains the most common ones associated with tolcapone. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any continue or become troublesome.

Very common tolcapone side-effects (these affect more than 1 in 10 people)

What can I do if I experience this?

Feeling sick (nausea), lack of appetite

Stick to simple foods - avoid rich or spicy meals


This can begin a couple of months after starting the tablets. Drink plenty of water and let your doctor know if this continues

Feeling tired or sleepy

Discuss this with your doctor, especially if you find yourself falling asleep during the day without feeling tired beforehand

Feeling dizzy

Getting up or moving more slowly should help. If you begin to feel dizzy, lie down so that you do not faint, then sit for a few moments before you stand


Drink plenty of water and ask your doctor or pharmacist to recommend a suitable painkiller

Uncontrolled or unusual body movements, feeling confused, seeing or hearing things that are not real, difficulty sleeping

Let your doctor know if you experience any of these

Tolcapone can cause liver problems. You should tell your doctor immediately if you lose your appetite, feel sick or have pain in your tummy (abdomen), develop dark-coloured urine or itchy skin, or if you feel generally tired or unwell.

If you experience other symptoms which you think may be due to the tablets, speak with your doctor or pharmacist for further advice.

How to store tolcapone

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you buy any medicines, check with a pharmacist that they are suitable to take with your prescribed medicines.

If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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