Levodopa and carbidopa

Commonly called Sinemet

The combination of levodopa and carbidopa is used to treat the symptoms of Parkinson's disease. Find out how to take it safely and possible side effects. Levodopa and carbidopa is also called Sinemet.

Type of medicine Also called
  • Dopaminergic medicine
  • It belongs to a group of medicines to treat symptoms of Parkinson's disease
  • Sinemet®
  • Sinemet CR®

What is levodopa + carbidopa?

Levodopa + carbidopa in combination is used to treat the symptoms of Parkinson's disease, or Parkinson-like symptoms such as tremor, shakiness, stiffness, and difficulty moving. Levodopa changes into dopamine, a chemical in the brain that helps control movement. Carbidopa prevents levodopa changing to dopamine in the bloodstream. This means that more levodopa can enter the brain, and it helps to lessen some of the side effects such as nausea (feeling sick) and vomiting (being sick). 

Levodopa becomes less effective over time. This is because it treats the symptoms of Parkinson's but cannot stop the dopamine-producing cells from being lost. This means that as they are lost you will continue to get symptoms and need more frequent doses over time. 

Your brain can’t become resistant to levodopa. People with Parkinson’s will benefit from medications containing levodopa throughout their lifetime.


In Aotearoa New Zealand, the levodopa + carbidopa combination is available in different forms and strengths with different amounts of carbidopa and levodopa in each tablet. This combination is available in 2 forms, tablets and controlled-release tablets (Also called modified-release). Controlled release means that the tablets release the medicine slowly over several hours. This means the effect of the medicine lasts longer than that of standard tabletsCheck with your pharmacist which form you are taking. Your doctor may prescribe the tablets and the controlled release tablets, to be taken at different times of the day.

Tablets: Sinemet 25/100; Sinemet 25/250
Controlled-release tablets: Sinemet CR

  • The dose of levodopa + carbidopa combination is different for different people. 
  • You will be started on a low dose and depending on your response, your doctor will increase your dose to control your symptoms.
  • Always take your levodopa + carbidopa exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much levodopa + carbidopa to take, how often to take it, and any special instructions.

How to take levodopa + carbidopa

  • Tablets: swallow the tablet whole, with a glass of water. If you are struggling to swallow the tablets, the tablets can be crushed and mixed with a liquid or soft food such as a spoonful of yoghurt.
  • Modified release tablet (has CR after the name): swallow the tablet whole, with a glass of water. Do not crush or chew the tablets because all the medicine will be released at once, increasing your chance of side effects and causing a loss in symptom control.
  • Timing: Take your tablet at the same times each day. You can take levodopa + carbidopa combination with or without food, but it is best NOT to take doses immediately after a large meal. Avoid taking levodopa + carbidopa with a high-protein meal because the protein you eat may decrease the effects of this medicine. 
  • Missed dose: If you do miss a dose and it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time or very close together.
  • Keep taking levodopa + carbidopa regularly. Do not stop taking levodopa + carbidopa or lower the dose, without checking with your doctor. Your doctor may want you to gradually reduce the amount of levodopa + carbidopa you are using before stopping completely. This may help reduce the possibility of withdrawal symptoms such as muscle stiffness, fever and mental changes.

Managing levodopa and protein

For some people with Parkinson’s, protein (which is found mainly in meat, fish, eggs, cheese, beans and pulses) seems to interfere with how well levodopa medications are absorbed by the body. Because of this, you may benefit from taking your medication 30–60 minutes before you eat a meal.

You may also benefit from a protein redistribution diet, where you take most of your daily protein in the evening. This can help the levodopa treatment to be more effective in the daytime, when you are likely to need it more.

Protein is essential for a healthy diet so you should not reduce your overall intake. Talk to your doctor before you make any changes to what you eat.

What are the side effects of levodopa + carbidopa?

Like all medicines, levodopa + carbidopa can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Changes in the colour of your urine, sweat or saliva – it may turn red, brown or black 
  • This is harmless and is nothing to worry about.
  • Falling asleep suddenly during daily activities (such as talking on the phone, or driving)
  • This sleep effect can occur without any feelings of drowsiness beforehand, and can happen anytime during treatment with this medication, including up to 1 year after starting the medication
  • Tell your doctor.
  • Do not drive or use tools until you know how this medicine affects you and until these have stopped happening.
  • Avoid drinking alcohol.
  • Feeling sick (nausea)
  • Vomiting
  • Loss of appetite(not wanting to eat)
  • Changes in taste
  • These are quite common when you first start taking levodopa + carbidopa.
  • Try taking your doses after a light meal or with a low protein snack such as crackers.
  • Tell your doctor if these bother you.
  • Feeling dizzy when you stand up
  • Be careful when getting up from either lying down or sitting to avoid falls.
  • Tell your doctor.
  • Changes in your mood such as feeling anxious, nervous or agitated, or feeling excited or depressed
  • Tell your doctor.
  • Uncontrollable jerky movements, where you switch suddenly from being able to move to being immobile
  • Tell your doctor immediately or ring Healthline 0800 611 116 
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product


Levodopa + carbidopa can interact with some medications, herbal supplements and rongoā Māori, so check with your doctor or pharmacist before starting levodopa + carbidopa and before starting any new products.

Learn more

The following links provide further information on levodopa + carbidopa.

Levodopa and carbidopa NZ Formulary Patient Information
Sinemet Medsafe Consumer Information Sheet, NZ
Sinemet CR Medsafe Consumer Information Sheet, NZ
Medication used in the treatment of Parkinson's Parkinson's New Zealand
Parkinson's and complementary therapies Parkinson's New Zealand


Levodopa + carbidopa anhydrous NZ Formulary
Sinemet Medsafe, NZ
Sinemet CR Medsafe, NZ
The management of Parkinson’s disease – which treatments to start and when? BPAC, NZ, 2014 

Credits: Sandra Ponen, Pharmacist. Reviewed By: Maya Patel, MPharm PGDipClinPharm, Auckland Last reviewed: 23 Nov 2021