What is a Patient Information Leaflet and why is it useful?

The Patient Information Leaflet (PIL) is the leaflet included in the pack with a medicine. It is written for patients and gives information about taking or using a medicine. It is possible that the leaflet in your medicine pack may differ from this version because it may have been updated since your medicine was packaged.

Below is a text only representation of the Patient Information Leaflet. The original leaflet can be viewed using the link above.

The text only version may be available in large print, Braille or audio CD. For further information call emc accessibility on 0800 198 5000. The product code(s) for this leaflet is: PL 00025/0226.

SINEMET 12.5mg/50mg Tablets


SINEMET® 12.5 mg/50 mg Tablets


Read all of this leaflet carefully before you start taking this medicine.

  • Keep this leaflet. You may need to read it again.
  • If you have any further questions, ask your doctor or pharmacist.
  • This medicine has been prescribed for you. Do not pass it on to others. It may harm them, even if their symptoms are the same as yours.
  • If any of the side effects gets serious, or if you notice any side effects not listed in this leaflet, please tell your doctor or pharmacist.

In this leaflet:

1 What Sinemet is and what it is used for
2 Before you take Sinemet
3 How to take Sinemet
4 Possible side effects
5 How to store Sinemet
6 Further information

1. What Sinemet is and what it is used for

Sinemet improves the signs of Parkinson’s disease. Parkinson's disease is a long-term illness where:

  • you become slow and unsteady
  • your muscles feel stiff
  • you may develop shaking or trembling (called ‘tremor’).

If not treated, Parkinson's disease can make it hard for you to continue your normal daily activities.

Sinemet contains two different medicines called: levodopa and carbidopa.

  • levodopa turns into a material called ‘dopamine’ in your brain. The dopamine helps to improve the signs of your Parkinson’s disease.
  • carbidopa belongs to a group of medicines called ‘aromatic amino acid decarboxylase inhibitors’. It helps levodopa work more effectively by slowing the speed at which levodopa is broken down in your body.

2. Before you take Sinemet

Do not take Sinemet if:

  • you are allergic (hypersensitive) to carbidopa or levodopa or any of the other ingredients of Sinemet (listed in Section 6)
  • you have ever had skin cancer or you have any unusual moles which have not been examined by your doctor
  • you are taking certain medicines called ‘MAOIs’ (Monoamine Oxidase Inhibitors) used for depression. You need to stop using these medicines at least two weeks before you start Sinemet (see also under ‘Taking other medicines’ below).
  • you have a condition called ‘narrow-angle glaucoma’ that may cause a sudden build up of pressure in the eye
  • you have a severe mental disorder
  • you are pregnant, might become pregnant, or are breast-feeding.

Do not take Sinemet if any of the above apply to you. If you are not sure, talk to your doctor or pharmacist before taking Sinemet.

Take special care with Sinemet

Check with your doctor or pharmacist before taking your medicine if:

  • you have a history of fits (convulsions)
  • you have had an ulcer in your gut (called ‘duodenal’ or ‘peptic ulcer’) or have vomited blood
  • you have had a heart attack, heart beat problems, circulation or breathing problems
  • you have had kidney, liver or hormonal problems
  • you have had depression or other mental problems
  • you have a condition called ‘chronic wide-angle glaucoma’ that may cause a build up of pressure in the eye. You will need to have regular checks on the pressure in your eye.
  • you sometimes have sudden sleep attacks or sometimes feel very sleepy
  • you are due to have surgery.

If you are not sure if any of the above apply to you, talk to your doctor or pharmacist before taking Sinemet.

Tell your doctor if you or your family/carer notices you are developing addiction-like symptoms leading to craving for large doses of Sinemet and other medicines used to treat Parkinson’s disease.

Tell your doctor if you or your family/carer notices you are developing urges or cravings to behave in ways that are unusual for you or you cannot resist the impulse, drive or temptation to carry out certain activities that could harm yourself or others. These behaviours are called impulse control disorders and can include addictive gambling, excessive eating or spending, an abnormally high sex drive or an increase in sexual thoughts or feelings. Your doctor may need to review your treatments.

Taking other medicines

Please tell your doctor or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription. This includes herbal medicines. This is because Sinemet can affect the way some other medicines work. Also some other medicines can affect the way Sinemet works.

In particular tell your doctor or pharmacist if you are taking any of the following medicines:

  • Medicines for Parkinson’s disease containing levodopa:
    • If they are ‘slow release’, you will need to wait 24 hours after your last dose before starting Sinemet.
    • If they are ‘normal release’, you will need to wait 12 hours after your last dose before starting Sinemet.
    • Tell the doctor or pharmacist even if you have only taken them in the past.
      Medicines for Parkinson’s disease which do not contain levodopa will usually be continued. However, your dose may be changed.
  • Medicines for mental problems (including depression), tuberculosis (TB), high blood pressure, muscle spasms, epilepsy or other diseases related to involuntary movements. Your dose may need to be changed.
  • Medicines to treat low iron. Your dose may need to be changed.
  • Medicines called ‘MAOIs’ (see also ‘Do not take Sinemet if’).
  • Anticholinergic medicines (such as orphenadrine, trihexyphenidyl, benzatropine and procyclidine). Your dose may need to be changed.
  • Phenytoin which is used to treat fits (convulsions).
  • Papaverine which is used to treat impotence in men.

If you are not sure if any of the above apply to you, talk to your doctor or pharmacist before taking this medicine. Your doctor or pharmacist has a more complete list of medicines to avoid while taking Sinemet.

Tests while you are taking Sinemet

This medication can affect some laboratory tests that your doctor may perform on blood or urine samples. Please remind your doctor if you are taking Sinemet and are having any tests.

Taking Sinemet with food and drink

Try to avoid taking your tablets with a heavy meal. If your diet contains too much protein (meat, eggs, milk, cheese) Sinemet may not work as well as it should.

Pregnancy and breast-feeding

Do not take Sinemet if you are pregnant, might become pregnant or are breast-feeding. Levodopa, one of the substances in Sinemet, is passed into human milk.

Ask your doctor or pharmacist for advice before taking any medicine, if you are pregnant or breast-feeding.

Driving and using machines

  • Sinemet affects different people in different ways. Some people have side effects which affect their ability to drive or use tools or machines (see Section 4 Possible side effects). Do not drive or use tools or machines if you get these effects.
  • Sinemet can also make you sleepy or cause 'sudden sleep attacks'. If this happens to you, you must not drive or use tools or machines. Your doctor will tell you if you can start driving again if these attacks stop.

3. How to take Sinemet

Always take Sinemet exactly as your doctor has told you. You should check with your doctor or pharmacist if you are not sure.

Taking this medicine

  • Take this medicine by mouth.
  • Although your medicine can have an effect after one day, it may take up to seven days to work.
  • Take them at regular time intervals according to your doctor's instructions.
  • Do not change the times at which you take your tablets or take any other medicines for Parkinson's disease without first consulting your doctor.
  • Try to avoid taking your tablets with a heavy meal.

If you have not had levodopa before

The usual starting dose for Sinemet 12.5 mg/50 mg Tablets is one tablet three or four times a day.

If you have had levodopa before

Your doctor will ask you to stop taking your medicine for Parkinson’s disease before you start taking Sinemet.

The usual starting dose will depend on what you were taking before.

More than one Sinemet product may be prescribed by your doctor. If you have been given different Sinemet tablets to take make sure that you are taking the correct one at the right time.

Children under 18 years of age

Sinemet is not suitable for children under the age of 18 years.

If you take more Sinemet than you should

If you take too many tablets see your doctor immediately.

If you forget to take Sinemet

Do not take a double dose to make up for a forgotten dose.

If you stop taking Sinemet

Do not stop taking Sinemet or change your dose without talking to your doctor first. When you stop taking Sinemet the following can occur: stiff muscles, high temperature (fever) and mental changes.

If you have any further questions on the use of this product, ask your doctor or pharmacist.

4. Possible side effects

Like all medicines, Sinemet can cause side effects, although not everybody gets them.

Stop taking Sinemet and see your doctor straight away, if you notice any of the following side effects:

  • allergic reaction, the signs may include hives (nettle rash), itching, rash, swelling of your face, lips, tongue or throat. This may cause difficulty in breathing or swallowing
  • chest pain
  • uneven (irregular) heart beat or palpitations
  • dizziness on standing-up quickly
  • bleeding from your gut which may be seen as blood in your faeces or darkened faeces (gastro-intestinal bleeding)
  • blood problems, the signs may include pale skin (pallor), tiredness, fever, sore throat or mild bruising and prolonged bleeding after injury
  • stiff muscles, high fever
  • mental changes including delusions, hallucinations and depression
  • fits (convulsions).

The most common side effects are

  • abnormal movements such as twitching or spasms (which may or may not be like your Parkinson's symptoms)
  • nausea.

Other side effects include

  • fainting, anorexia, high blood pressure
  • inflammation of the veins, being sick (vomiting), diarrhoea, discoloration of urine, sweat or saliva
  • on-off phenomenon, characteristic of some people with long-standing Parkinson’s disease. This is when you can have unpredictable changes from being mobile - “on” - to a sudden inability to move - “off”. “Off” to “on” can occur just as suddenly.
  • dizziness; sleepiness (including excessive drowsiness or sudden sleep onset episodes), pins and needles
  • dream abnormalities, confusion, feeling agitated, shortness of breath, hair loss

You may experience the following side effects:

  • Craving for large doses of Sinemet in excess of that required to control motor symptoms, known as dopamine dysregulation syndrome. Some patients experience severe abnormal involuntary movements (dyskinesias), mood swings or other side effects after taking large doses of Sinemet.
  • inability to resist the impulse to perform an action that could be harmful, which may include:
    • strong impulse to gamble excessively despite serious personal or family consequences.
    • altered or increased sexual interest and behaviour of significant concern to you or to others, for example, an increased sexual drive.
    • uncontrollable excessive shopping or spending.
    • binge eating (eating large amounts of food in a short time period) or compulsive eating (eating more food than normal and more than is needed to satisfy your hunger).

Tell your doctor if you experience any of these behaviours; he/she will discuss ways of managing or reducing the symptoms.

Side effects that have been reported with medicines containing levodopa.

These may be experienced when taking Sinemet.

Nervous system:

  • loss of control over the voluntary movements of everyday life
  • numbness, increased hand tremor, muscle twitching, muscle cramp, irregular movement of jaw muscles resulting in difficulty opening the mouth
  • difficulty sleeping, feeling anxious or high, falling over and abnormal walking patterns
  • headache


  • drooping eyelid and dilated pupil
  • changes in vision, irregular movement of the eye

Digestive system:

  • indigestion, dry mouth, bitter taste
  • swelling of the salivary glands, difficulty swallowing, grinding of the teeth
  • hiccups, abdominal pain and distress, constipation, wind
  • burning sensation of the tongue.


  • persistent abnormal erection of the penis


  • difficulty passing urine or incontinence (inability to control urine flow)


  • changed patches of pigmented skin, including, irritated or irregular moles, or moles in which you have noticed changes (melanoma)


  • weight gain or loss, swelling in the limbs
  • flushing, hot flushes, increased sweating
  • feeling weak, faint or tired
  • hoarseness, general feeling of being unwell
  • increased energy or activity, unusual breathing pattern

If any symptoms persist or you experience any other side effects please tell your doctor or pharmacist. It will help if you make a note of what you experienced, when it started and how long it lasted.

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Sinemet

  • Keep out of the sight and reach of children
  • Do not store above 25°C. Store in the original package in order to protect from light
  • Do not use Sinemet after the expiry date which is stated on the blister and carton after ‘EXP.’ The expiry date refers to the last day of that month.
  • Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.

6. Further information

What Sinemet contains

  • The active substances in Sinemet 12.5 mg/50 mg Tablets are carbidopa (equivalent to 12.5 mg anhydrous carbidopa) and levodopa (50 mg).
  • The other ingredients in Sinemet 12.5 mg/50 mg Tablets are microcrystalline cellulose, maize starch, magnesium stearate, pregelatinised maize starch, and quinoline yellow (E104).

What Sinemet looks like and contents of the pack

Sinemet ® 12.5 mg/50 mg Tablets:

Yellow, oval-shaped tablets, one side scored and the other marked ‘520’.

Sinemet 12.5 mg/50 mg Tablets are available in blister packs of 90 tablets.

Marketing Authorisation Holder and Manufacturer

Marketing Authorisation Holder:

Organon Pharma (UK) Limited
Hertford Road
EN11 9BU


Merck Sharp & Dohme B.V.
Waarderweg 39
2031 BN
The Netherlands

This leaflet was last revised in February 2021.

© Organon Pharma (UK) Limited 2021. All rights reserved.