Carbidopa levodopa 25-100 mg



Sinemet is the brand name of the combination medicine that contains the drugs levodopa and carbidopa.

It’s used to treat symptoms of Parkinson’s disease, which may include tremors, shaking, stiffness, or movement problems.

The prescription drug can also treat Parkinson’s-like symptoms after encephalitis (inflammation of the brain) or an injury to the nervous system that’s caused by carbon monoxide or heavy metal poisoning.

Levodopa is in a class of drugs known as central nervous system agents. It works by converting to dopamine (a neurotransmitter in the brain that affects emotions and movement).

Sinemet was approved by the Food and Drug Administration (FDA) in 1988. It’s manufactured by Merck Sharp & Dohme Corp.

Sinemet Warnings

Before taking Sinemet, tell your doctor if you have or have ever had:

  • Glaucoma (a group of eye disorders)
  • Melanoma (a type of skin cancer)
  • A skin growth that hasn’t been diagnosed
  • Hormone problems
  • Asthma, emphysema, or other lung disease
  • Mental illness
  • Sleep disorders
  • Diabetes
  • Ulcers
  • A heart attack
  • An irregular heartbeat
  • Heart, kidney, liver, or blood vessel disease

Tell your physician you’re taking Sinemet before having any type of surgery, including a dental procedure.

This medicine can cause false results on certain urine tests. Make sure you tell all laboratory personnel you’re taking Sinemet.

Also tell your health care provider if you plan on changing your diet to include foods that are high in protein or fat.

Your saliva, urine, and sweat might appear dark-colored red, brown, or black while you’re taking Sinemet. This is a harmless effect.

Some people have experienced new or unusual urges (such as gambling or sexual impulses) while taking this medicine. Talk to your doctor if you notice this symptom.

Sinemet might lose its effectiveness over time or at certain times during the day. Call your doctor if your symptoms worsen or vary.

This medicine controls symptoms of Parkinson’s, but it doesn’t cure the disease. Continue to take Sinemet even if you feel well.

Don’t stop taking this medicine without first talking to your doctor because you may experience unwanted side effects and a potentially dangerous condition known as neuroleptic malignant syndrome (NMS).

Your doctor will probably gradually decrease your dose of Sinemet if you stop taking it.

Pregnancy and Sinemet

It’s not known whether Sinemet will harm an unborn baby.

Tell your doctor if you’re pregnant or plan to become pregnant before taking this medicine.

The drug can also pass into breast milk. Don’t breastfeed a baby without first talking to your physician if you’re taking Sinemet.

13 Medications to Help Control Parkinson’s Disease Symptoms

Picking a Parkinson’s medication

When assessing which medications will work best, we ask patients the following questions:

  • Are you able to do what you want to do?

  • Are the medications you are taking now wearing off before the next dose?

  • Do your medications have side effects? If so, what are they?

  • Are you having dyskinesias (extra involuntary movements)? If so, how bothersome are they to you?

Based on the answers to those questions and the medical exam, we choose a medication from the following list:

Carbidopa-levodopa (Sinemet): The most effective and well-tolerated drug the medical profession has to offer at this time is carbidopa-levodopa. It often helps with bradykinesia (rigidity and rest tremor). It generally does not help with imbalance or falls, freezing and non-motor symptoms.

Side effects include:

  • Dyskinesia (abnormal, involuntary movements)

  • Nausea

  • Hallucinations

  • Confusion

  • Lightheadedness

Patients should also be aware of these important dosing instructions:

  • Take 30 minutes prior to meals (note that a high-protein diet may decrease absorption of the drug).

  • Generally, do not take it right before bed unless you need it overnight to reduce cramping or restless leg syndrome.

  • Consistent timing is important. If you miss a dose, your symptoms may return.

Sinemet controlled-release tab: This drug can be given at night to help with early morning symptoms, or it may be used instead of the immediate-release version to decrease nausea.

  • It has not been shown to help treat motor fluctuations (variable “on-and-off,” early morning “off,” etc.) and dyskinesia.

Rytary: This drug is a new, long-acting carbidopa-levodopa.

  • It provides an extra one to two hours of “on” time per day compared with regular Sinemet.

  • Rytary is not available in a generic version, so it may be expensive. Some insurance companies do cover it.

Dopamine agonists (pramipexole, ropinirole, rotigotine patch): There is good evidence to support that these medications work by themselves or in combination with Sinemet. If they are used in combination, it helps prolong the effect of the Sinemet.

  • Significant side effects can limit their use, including:

  • Nausea

  • Dizziness

  • Leg swelling

  • Sleepiness and sleep attacks

  • Worsening cognition

  • Hallucinations

  • Impulse control disorders

Apomorphine: Effective in patients with severe motor fluctuations, it can be useful to get patients going in the early morning or during “off” times.

  • This medication is injected, which many people don’t like. In addition, it can cause severe nausea, so it requires scheduled anti-nausea therapy. The first dose will need to be monitored in the office to ensure safety, tolerability and adequate dosing.

SEE ALSO: Deep Brain Stimulation for Parkinson’s Disease: Is It Right for You?

MAO-B inhibitors (selegiline, rasagiline): These may have a mild symptomatic benefit early in the course of Parkinson’s disease.

  • Similar to dopamine agonists, this medication may help to smooth the motor fluctuations in advanced disease.

  • They may also be used with Sinemet to prolong the action of the Sinemet.

  • Many people with Parkinson’s have mood disorders, and there could be a drug interaction if these medications are taken with certain antidepressants. Patients should be watched closely.

COMT inhibitors (entacapone, tolcapone): These drugs decrease “wearing off” in advanced disease.

  • They may make the side effects of carbidopa-levadopa worse.

Amantadine: This may have a modest effect on motor symptoms in early Parkinson’s, but it is particularly helpful with treating dyskinesia.

  • Cognitive (thinking and memory) side effects may limit its use.

Trihexyphenidyl (Artane): This can be helpful in treating rest tremor if refractory to Sinemet and dopamine agonists, but side effects may limit its use.

Nonpharmacologic treatments

If you have a neurologist, he or she will harp on exercise, exercise, exercise. People with Parkinson’s disease who participate in exercise and exercise therapies will improve their ability to function. We encourage 30 minutes of activity every day.

Speech therapy is also beneficial because patients often develop a soft voice, and they can learn how to project their voice. Such therapy may also help if they develop swallowing problems.

Sinemet 25-100 (Oral)

Generic Name: carbidopa and levodopa (Oral route)

kar-bi-DOE-pa, lee-voe-DOE-pa

Medically reviewed by Last updated on Jan 11, 2019.

  • Overview
  • Side Effects
  • Dosage
  • Professional
  • Interactions
  • More

Commonly used brand name(s)

In the U.S.

  • Parcopa
  • Rytary
  • Sinemet 10-100
  • Sinemet 25-100
  • Sinemet 25-250
  • Sinemet CR

In Canada

  • Sinemet 100/10
  • Sinemet 100/25
  • Sinemet 250/25
  • Sinemet CR 100/25
  • Sinemet CR 200/50

Available Dosage Forms:

  • Tablet, Extended Release
  • Tablet
  • Capsule, Extended Release
  • Tablet, Disintegrating

Therapeutic Class: Antiparkinsonian

Pharmacologic Class: Decarboxylase Inhibitor

Uses for Sinemet 25-100

Carbidopa and levodopa combination is used to treat Parkinson’s disease, sometimes called shaking palsy or paralysis agitans. Parkinson’s disease is a disorder of the central nervous system (brain and spinal cord).

Extended-release carbidopa and levodopa (Rytary®) is also used to treat parkinsonism caused by encephalitis, or parkinsonism caused by carbon monoxide or manganese poisoning.

Dopamine is a naturally occurring substance in the brain that helps provide control of movement and activities such as walking and talking. In patients with Parkinson’s disease, there is not enough dopamine in some parts of the brain. Levodopa enters the brain and helps replace the missing dopamine, which allows people to function better. By increasing the amount of dopamine in the brain, levodopa helps control symptoms and helps you to perform daily activities such as dressing, walking, and handling utensils.

This medicine is available only with your doctor’s prescription.

Before using Sinemet 25-100

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of levodopa and carbidopa combination in the pediatric population. Safety and efficacy have not been established.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of Rytary® in the elderly.

Although appropriate studies on the relationship of age to the effects of Lodosyn® have not been performed in the geriatric population, geriatric-specific problems are not expected to limit the usefulness of Lodosyn® in the elderly. However, elderly patients are more likely to have age-related kidney, liver, or heart problems, which may require caution and an adjustment in the dose for patients receiving Lodosyn®.

No information is available on the relationship of age to the effects of carbidopa and levodopa combination in geriatric patients.


Pregnancy Category Explanation
All Trimesters C Animal studies have shown an adverse effect and there are no adequate studies in pregnant women OR no animal studies have been conducted and there are no adequate studies in pregnant women.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Amisulpride
  • Bromopride
  • Clorgyline
  • Furazolidone
  • Iproniazid
  • Isocarboxazid
  • Linezolid
  • Methylene Blue
  • Moclobemide
  • Nialamide
  • Pargyline
  • Phenelzine
  • Procarbazine
  • Sulpiride
  • Toloxatone
  • Tranylcypromine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Bupropion
  • Isoniazid
  • Macimorelin
  • Metoclopramide

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Droxidopa
  • Fosphenytoin
  • Indinavir
  • Iron
  • Kava
  • Phenylalanine
  • Phenytoin
  • Spiramycin
  • Tyrosine

Interactions with food/tobacco/alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

  • High Protein Food

Other medical problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Asthma or
  • Depression, history of or
  • Dyskinesia (abnormal muscle movements) or
  • Endocrine disease or
  • Heart attack, history of or
  • Heart or blood vessel disease, severe or
  • Heart rhythm problems (eg, ventricular tachycardia) or
  • Kidney disease or
  • Liver disease or
  • Lung disease, severe or
  • Peptic ulcer, history of or
  • Psychosis (mental disorder), or history of or
  • Wide-angle glaucoma (eye pressure problem)—Use with caution. May make these conditions worse.
  • Melanoma (skin cancer), suspicious or a history of or
  • Narrow angle glaucoma (eye pressure problem) or
  • Skin lesions, undiagnosed (rashes that involve changes in color or texture of the skin)—Should not be used in patients with these conditions.
  • Phenylketonuria (PKU)—The oral disintegrating tablet contains phenylalanine, which can make this condition worse.

Proper use of carbidopa and levodopa

This section provides information on the proper use of a number of products that contain carbidopa and levodopa. It may not be specific to Sinemet 25-100. Please read with care.

Take this medicine exactly as directed, and every time that you are supposed to take it. It is important that you do not stop taking your medicine unless ordered by your doctor. It is also important to not start taking other medicines for your Parkinson’s disease without first talking with your doctor.

You may experience a “wearing-off” effect towards the end of the dosing interval. You should tell your doctor if you have problems with this that affect your every day life. Your doctor may want to adjust your dose.

Since protein may interfere with the body’s response to carbidopa and levodopa, high protein diets should be avoided. Intake of normal amounts of protein should be spaced equally throughout the day, or taken as directed by your doctor.

If you are taking multivitamin tablets or plan to start taking them, discuss this first with your doctor. Iron salts (in vitamins) may keep this medicine from working properly.

Sinemet® tablet or Parcopa® disintegrating tablet begins to release its ingredients 30 minutes after you take it.

Swallow the extended-release capsule or sustained release tablet whole. Do not crush, break, or chew it.

If you have trouble swallowing the extended-release capsules: The capsules can be opened and the contents can be sprinkled on 1 to 2 tablespoons of applesauce. This mixture must be swallowed immediately without chewing.

If you are using the disintegrating tablet, make sure your hands are dry before you handle the tablet. Do not remove the tablet from the bottle until you are ready to take it. Place the tablet on the top of your tongue, where it will melt quickly.

Use only the brand of this medicine that your doctor prescribed. Different brands may not work the same way.


The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For Parkinson’s disease:
    • For oral dosage form (extended-release capsules):
      • Adults—
        • For patients starting on carbidopa and levodopa treatment: At first, one capsule three times a day for the first 3 days. Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more than 10 capsules per day.
        • For patients taking carbidopa and levodopa already: At first, 3 or 4 capsules three times a day. Your doctor may adjust your dose as needed and tolerated. However, the dose is usually not more than 10 capsules per day.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (disintegrating tablets):
      • Adults—
        • For patients starting on carbidopa and levodopa treatment: At first, one tablet three or four times a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 8 tablets per day.
        • For patients taking levodopa already: Levodopa should be discontinued at least 12 hours before starting Parcopa®. The starting dose is one tablet three or four times a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 8 tablets per day.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (sustained release tablets):
      • Adults—
        • For patients switching from Sinemet® to Sinemet® CR: The starting dose is based on the amount of Sinemet® you are currently taking per day. Your doctor may adjust your dose as needed.
        • For patients taking levodopa already: Levodopa should be discontinued at least 12 hours before starting Sinemet® CR. The starting dose is one tablet two times a day. Your doctor may adjust your dose as needed.
        • For patients not taking levodopa: At first, one tablet two times a day. Your doctor may adjust your dose as needed.
      • Children—Use and dose must be determined by your doctor.
    • For oral dosage form (tablets):
      • Adults—
        • For patients starting on carbidopa and levodopa treatment: At first, one tablet three or four times a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 200 mg per day.
        • For patients taking levodopa already: Levodopa should be discontinued at least 12 hours before starting Lodosyn® plus levodopa or Sinemet®. The starting dose is one tablet three or four times a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 200 mg per day.
        • For patients taking carbidopa and levodopa already: 25 milligrams (mg) of Lodosyn® per day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 200 mg per day.
      • Children—Use and dose must be determined by your doctor.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions while using Sinemet 25-100

It is very important that your doctor check your progress at regular visits to allow changes in your dose and to check for any unwanted effects.

Do not take this medicine if you have taken a monoamine oxidase (MAO) inhibitor (eg, phenelzine, tranylcypromine, Nardil®, Parnate®) in the past 2 weeks.

Do not stop taking this medicine without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping completely.

Check with your doctor right away if you are having convulsions (seizures), difficulty with breathing, a fast heartbeat, a high fever, high or low blood pressure, increased sweating, loss of bladder control, severe muscle stiffness, unusually pale skin, or tiredness. These could be symptoms of a serious condition called neuroleptic malignant syndrome (NMS).

This medicine may cause dizziness, drowsy, trouble in controlling movements, or trouble in concentrating or seeing clearly. Make sure you know how you react to this medicine before you drive, use machines, or do other jobs that require you to be alert, well-coordinated, or able to think or see well.

It is important that your doctor check your skin regularly for signs of a skin cancer called melanoma. If you notice any unusual red, brown, or black spots on your skin, talk to your doctor right away.

If you develop any unusual or strange thoughts and behavior while receiving this medicine, be sure to discuss it with your doctor. Other changes might be confusion, worsening of depression, visual hallucinations (seeing things that are not there), suicidal thoughts, and unusual excitement, nervousness, or irritability.

It is possible that a dark color (red, brown, or black) may appear in saliva, urine, or sweat after taking this medicine. The color may cause some of your garments to become discolored. This is normal and nothing to worry about.

It is possible that you may become nauseous, especially when you are first starting your medicine.

Some people who have used this medicine had unusual changes in their behavior. Talk with your doctor right away if you start having problems with gambling or an increased interest in sex while using this medicine.

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter ) medicines and herbal or vitamin supplements.

Sinemet 25-100 side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  • Twitching, twisting, uncontrolled repetitive movements of the tongue, lips, face, arms, or legs

Less common

  • Bladder pain
  • bloody or cloudy urine
  • chest pain
  • confusion
  • difficult, burning, or painful urination
  • discouragement
  • feeling sad or empty
  • frequent urge to urinate
  • inability to move the eyes
  • increased blinking or spasms of the eyelid
  • irritability
  • lack of appetite
  • loss of interest or pleasure
  • lower back or side pain
  • seeing, hearing, or feeling things that are not there
  • sticking out of tongue
  • tiredness
  • trouble concentrating
  • trouble in breathing, speaking, or swallowing
  • trouble sleeping
  • uncontrolled twisting movements of the neck, trunk, arms, or legs
  • unusual facial expressions

Incidence not known

  • Anxiety
  • black, tarry stools
  • bluish color
  • blurred vision
  • changes in skin color
  • chest discomfort
  • chills
  • convulsions
  • cough or hoarseness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • dry mouth
  • false beliefs that cannot be changed by facts
  • fast, irregular, pounding, or racing heartbeat or pulse
  • feelings about hurting oneself or others
  • fever with or without chills
  • general feeling of tiredness or weakness
  • high fever
  • hyperventilation
  • increased in sexual ability, desire, drive, or performance
  • increased interest in sexual intercourse
  • increased sweating
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • loss of bladder control
  • lower back or side pain
  • nausea
  • pain
  • pain or discomfort in the arms, jaw, back, or neck
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • severe muscle stiffness
  • shaking
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swelling of the foot or leg
  • swollen glands
  • tenderness
  • tiredness
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusually pale skin
  • vomiting

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

  • Acid or sour stomach
  • back or shoulder pain
  • belching
  • body aches or pain
  • burning, crawling, itching, numbness, prickling, “pins and needles”, or tingling feelings
  • diarrhea
  • difficulty having a bowel movement (stool)
  • ear congestion
  • headache
  • heartburn
  • indigestion
  • loss of voice
  • muscle cramps
  • nasal congestion
  • runny nose
  • sneezing
  • stomach discomfort, upset, or pain
  • unusual dreams
  • weight loss

Incidence not known

  • Abdominal or stomach distress
  • bad, unusual, or unpleasant (after) taste
  • belching
  • change in taste
  • dark sweat
  • double vision
  • enlarged pupils
  • feeling of warmth
  • hair loss or thinning of the hair
  • lack or loss of strength
  • redness of the face, neck, arms, and occasionally, upper chest
  • seeing double
  • skin rash, hives or welts, itching

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 2019 Truven Health Analytics, Inc. All Rights Reserved.

Medical Disclaimer

More about carbidopa / levodopa

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  • Drug class: dopaminergic antiparkinsonism agents

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SIDE EFFECTS: Dizziness, nausea, vomiting, trouble sleeping, and headache may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.This medication may cause your urine, sweat or saliva to turn red, brown, or black. This is harmless, but your clothes may become discolored.Tell your doctor immediately if any of these unlikely but serious side effects occur: greatly increased eye blinking/twitching, irregular heartbeat, fainting, mental/mood changes (e.g., confusion, depression, hallucinations, thoughts of suicide), worsening of involuntary movements/spasms.Tell your doctor immediately if any of these rare but very serious side effects occur: easy bleeding/bruising, signs of infection (e.g., fever, persistent sore throat), tingling of the hands/feet, vision changes (e.g., blurred/double vision).Seek immediate medical attention if any of these rare but very serious side effects occur: chest pain, seizures, vomit that looks like coffee grounds, black/tarry stools.Abruptly stopping or reducing the dose of this medication may rarely cause a serious (sometimes fatal) condition (neuroleptic malignant syndrome). Seek immediate medical attention if any of these rare but very serious side effects occur: fast/shallow breathing, confusion, severe dizziness/fainting, high fever, unusual muscle stiffness, unusual sweating.For males, in the very unlikely event you have a painful or prolonged erection (lasting more than 4 hours), stop using this drug and seek immediate medical attention or permanent problems could occur.A very serious allergic reaction is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada – Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking this medication, tell your doctor or pharmacist if you are allergic to carbidopa or levodopa; or if you have any other allergies.This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain eye problem (narrow-angle glaucoma).Before using this medication, tell your doctor or pharmacist your medical history, especially of: bleeding disorders, breathing problems (e.g., asthma, emphysema), certain eye problem (wide-angle glaucoma), heart or blood vessel problems (e.g., arrhythmias, heart attack, angina), kidney disease, liver disease, mental/mood disorders (e.g., depression, schizophrenia), peptic ulcer, seizure.This drug may make you dizzy or cause blurred vision. Do not drive, use machinery, or do any activity that requires alertness or clear vision until you are sure you can perform such activities safely. Avoid alcoholic beverages.To minimize lightheadedness, get up slowly when rising from a sitting or lying position.Before having surgery, tell your doctor or dentist that you are taking this medication.This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.Levodopa may pass into breast milk and affect milk production. Because of the potential risk to the infant, breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.


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Sinemet is a drug approved by the U.S. Food and Drug Administration (FDA) for the treatment of symptoms associated with Parkinson’s disease. The drug is a combination of two amino-acids: levodopa (a central nervous system agent) and carbidopa (an agent inhibiting an enzyme called decarboxylase). Together, these two components increase the level of dopamine in the brain, which normally is low in Parkinson’s disease patients, leading to the motor impairments associated with the disease.

Merck commercializes Sinemet as tablets in three strengths with different concentrations of levodopa and carbidopa. Sinemet 25-100 contains 25 mg of carbidopa and 100 mg of levodopa, Sinemet 10-100 contains 10 mg of carbidopa and 100 mg of levodopa, and Sinemet 25-250, contains 25 mg of carbidopa and 250 mg of levodopa.

A new formulation of Sinemet with a controlled-release (CR) was approved by the FDA in 2014. Sinemet CR tablets contain either 50 mg of carbidopa and 200 mg of levodopa, or 25 mg of carbidopa and 100 mg of levodopa.

How Sinemet works

The underlying cause for the tremors, stiffness, and slowness of movements associated with Parkinson’s disease is the reduced level of dopamine (a neurotransmitter molecule) in the brain. However, the direct administration of dopamine is ineffective in the treatment of Parkinson’s disease because it cannot cross the blood-brain barrier and reach the brain.

Levodopa is a metabolic precursor of dopamine or a compound that participates in the chemical reaction that produces dopamine, which is able to cross the blood-brain barrier and reach the brain, where it can be converted to dopamine.

Carbidopa works by preventing the breakdown of levodopa by decarboxylase enzymes. Because it cannot cross the blood-brain barrier, carbidopa ensures the safe delivery of levodopa to the brain, where it becomes exposed to the action of the decarboxylases that generate dopamine.

The combination of carbidopa and levodopa enhances levodopa’s potential of action because it enables the use of much lower doses of levodopa (80% less), which helps reduce the drug’s side effects, which include nausea and vomiting.

Studies with Sinemet

Bial designed two clinical trials from 2012 to 2015 to investigate the effect of a drug called Opicapone on the beneficial effects of levodopa in Parkinson’s disease patients undergoing treatment with Sinemet (NCT02169479), or Sinemet CR (NCT02169453). Results showed that 50 mg once-daily of Opicapone achieved significant reductions (two hours) in absolute “off-time” and enhanced the beneficial effects of levodopa in Parkinson’s disease patients with motor fluctuations.

Intec Pharma is recruiting participants to join a 27-week, Phase 3, multicenter, global study in adults with fluctuating Parkinson’s disease (NCT02605434). The aim of the trial is to determine whether a gastric retentive carbidopa-levodopa treatment (Accordion Pill) is more effective than an immediate release carbidopa-levodopa treatment (Sinemet) in reducing motor fluctuations such as “off-time” events.

One trial is recruiting Parkinson’s disease patients in Canada for a two-week, Phase 4 study (NCT03111485) to assess whether long-acting treatment with Sinemet CR, taken at night time, improves obstructive sleep apnea.

Patients also are being recruited to enter trials to assess the effect of the carbidopa-levodopa combination in the treatment of other conditions, such as age-related macular degeneration (NCT03023059, NCT03022318) , retinitis pigmentosa (NCT02837640), stroke (NCT02386475), back pain (NCT01951105), albinism (NCT01663935), depression (NCT02513485) and substance abuse (NCT02080819 and NCT00439049).

Note: Parkinson’s News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.


The most common adverse reactions reported with SINEMET have included dyskinesias, such as choreiform, dystonic, and other involuntary movements, and nausea.

The following other adverse reactions have been reported with SINEMET:

Body as a Whole

Chest pain, asthenia.

Cardiac irregularities, hypotension, orthostatic effects including orthostatic hypotension, hypertension, syncope, phlebitis, palpitation.

Dark saliva, gastrointestinal bleeding, development of duodenal ulcer, anorexia, vomiting, diarrhea, constipation, dyspepsia, dry mouth, taste alterations.

Agranulocytosis, hemolytic and non-hemolytic anemia, thrombocytopenia, leukopenia.

Angioedema, urticaria, pruritus, Henoch-Schönlein purpura, bullous lesions (including pemphigus-like reactions).

Back pain, shoulder pain, muscle cramps.

Nervous System/Psychiatric

Psychotic episodes including delusions, hallucinations, and paranoid ideation, bradykinetic episodes (“on-off” phenomenon), confusion, agitation, dizziness, somnolence, dream abnormalities including nightmares, insomnia, paresthesia, headache, depression with or without development of suicidal tendencies, dementia, pathological gambling, increased libido including hypersexuality, impulse control symptoms. Convulsions also have occurred; however, a causal relationship with SINEMET has not been established.

Dyspnea, upper respiratory infection.


Rash, increased sweating, alopecia, dark sweat.


Urinary tract infection, urinary frequency, dark urine.

Laboratory Tests

Decreased hemoglobin and hematocrit; abnormalities in alkaline phosphatase, SGOT (AST), SGPT (ALT), LDH, bilirubin, BUN, Coombs test; elevated serum glucose; white blood cells, bacteria, and blood in the urine.

Other adverse reactions that have been reported with levodopa alone and with various carbidopa levodopa formulations, and may occur with SINEMET are:

Abdominal pain and distress, fatigue.

Myocardial infarction.

Gastrointestinal pain, dysphagia, sialorrhea, flatulence, bruxism, burning sensation of the tongue, heartburn, hiccups.

Edema, weight gain, weight loss.

Leg pain.

Ataxia, extrapyramidal disorder, falling, anxiety, gait abnormalities, nervousness, decreased mental acuity, memory impairment, disorientation, euphoria, blepharospasm (which may be taken as an early sign of excess dosage; consideration of dosage reduction may be made at this time), trismus, increased tremor, numbness, muscle twitching, activation of latent Horner’s syndrome, peripheral neuropathy.

Pharyngeal pain, cough.

Malignant melanoma (see also CONTRAINDICATIONS), flushing.

Special Senses

Oculogyric crises, diplopia, blurred vision, dilated pupils.

Urinary retention, urinary incontinence, priapism.


Bizarre breathing patterns, faintness, hoarseness, malaise, hot flashes, sense of stimulation.

Laboratory Tests

Decreased white blood cell count and serum potassium; increased serum creatinine and uric acid; protein and glucose in urine.

Read the entire FDA prescribing information for Sinemet (Carbidopa-Levodopa)

Sinemet Side Effects

Generic Name: carbidopa / levodopa

Medically reviewed by Last updated on Feb 7, 2019.

  • Overview
  • Side Effects
  • Dosage
  • Professional
  • Interactions
  • More

Note: This document contains side effect information about carbidopa / levodopa. Some of the dosage forms listed on this page may not apply to the brand name Sinemet.

For Healthcare Professionals

Applies to carbidopa / levodopa: enteral suspension, oral capsule extended release, oral tablet, oral tablet disintegrating, oral tablet extended release


The most common adverse reactions reported include nausea, dizziness, headache, insomnia, abnormal dreams, dry mouth, dyskinesia, anxiety, constipation, vomiting, and orthostatic hypotension.

Nervous system

Very common (10% or more): Headache (up to 17%), dyskinesia (up to 16.5%), dizziness (up to 12%)

Common (1% to 10%): Confusion, dystonia, on-off phenomena, hypoesthesia, polyneuropathy, tremor, dysgeusia, bradykinesia

Uncommon (0.1% to 1%): Paresthesia, ataxia, gait disturbance, convulsion

Rare (less than 0.1%): Malignant, neuroleptic syndrome

Frequency not reported: Chorea, somnolence, memory impairment, sense of stimulation

Postmarketing reports: Polyneuropathy


Very common (10% or more): Anxiety, insomnia, depression (up to 11%)

Common (1% to 10%): Hallucinations, psychosis, abnormal dreams, sleep disorder, agitation, impulsive behavior, sleep attacks

Uncommon (0.1% to 1%): Suicide, dementia, disorientation, euphoric mood, fear

Rare (less than 0.1%): Abnormal thinking

Postmarketing: Suicide attempt, suicidal ideation


Very common (10% or more): Nausea (up to 30%), constipation (up to 22%)

Uncommon (0.1% to 1%): Salivary hypersecretion

Rare (less than 0.1%): Bruxism, saliva discoloration, glossodynia, hiccups, trismus, burning tongue sensation

Frequency not reported: Heartburn


Common (1% to 10%): Ischemic events, orthostatic hypotension, peripheral edema, hypertension, syncope, irregular heart rate, hypotension

Uncommon (0.1% to 1%): Palpitations, phlebitis

Frequency not reported: Chest pain, myocardial infarction

Cardiovascular ischemic events occurred in 2.4% (7 of 289) patients receiving carbidopa-levodopa extended-release capsules compared to 1.1% (1 of 92) of patients receiving placebo in early Parkinson’s disease clinical trials. In advanced Parkinson’s disease, 0.7 % (3 of 450) patients experienced cardiovascular ischemic events. These patients had a previous history of ischemic heart disease or risk factors for ischemic heart disease.


Common (1% to 10%): Excessive granulation tissue, rash, contact dermatitis, hyperhidrosis, pruritus

Uncommon (0.1% to 1%): Alopecia, erythema, urticaria

Rare (less than 0.1%): Sweat discoloration, angioedema

Postmarketing reports: Henoch-Schonlein purpura


Insertion site complication was reported in 57% of patients who received this drug compared with 44% of patients who received a PEG-J tube without receiving treatment. The most common adverse reactions associated with naso-jejunal (NJ) insertion were oropharyngeal pain, abdominal distention, abdominal pain, abdominal discomfort, pain, throat irritation, gastrointestinal injury, esophageal hemorrhage, anxiety, dysphagia, and vomiting. The most common adverse reactions associated with PEG-J insertion included upper abdominal pain, duodenal ulcer, duodenal ulcer hemorrhage, erosive duodenitis, erosive gastritis, gastrointestinal hemorrhage, intussusception, peritonitis, post-operative abscess, and small intestine ulcer.

Very common (10% or more): Insertion site complication, incision site erythema (19%), post-operative wound infection

Common (1% to 10%): Incision site cellulitis, post procedural infection, device dislocation, device occlusion

Uncommon (0.1% to 1%): Postoperative abscess, bezoar, ischemic colitis

Postmarketing reports: Gastric perforation, gastrointestinal perforation, small intestinal ischemia, small intestinal perforation


Postmarketing reports: Anaphylactic reaction, bullous lesions


Common (1% to 10%): Upper respiratory tract infection, atelectasis, dyspnea, aspiration pneumonia, oropharyngeal pain

Uncommon (0.1% to 1%): Dysphonia, hoarseness

Rare (less than 0.1%): Abnormal respiration

Frequency not reported: Bizarre breathing pattern


Frequency not reported: Elevated alkaline phosphatases, AST, ALT, LDH, and bilirubin


Frequency not reported: Elevated serum urea and creatinine


Very common (10% or more): Asthenia, fatigue

Common (1% to 10%): Pyrexia, malaise

Frequency not reported: Hot flashes


Common (1% to 10%): Urinary tract infection, urinary incontinence, urinary retention

Uncommon (0.1% to 1%): Urinary frequency

Rare (less than 0.1%): Priapism


Common (1% to 10%): Anemia

Uncommon (0.1% to 1%): Leukopenia, thrombocytopenia

Rare (less than 0.1%): Hemolytic anemia

Very rare (less than 0.01%): Agranulocytosis

Frequency not reported: Positive Coombs test, reduced hemoglobin and hematocrit


Very common (10% or more): Decreased weight

Common (1% to 10%): Anorexia, increased weight, vitamin B6 deficiency, vitamin B12 deficiency

Frequency not reported: Elevated blood sugar

Postmarketing reports: Folic acid deficiency


Common (1% to 10%): Back pain, shoulder pain

Uncommon (0.1% to 1%): Muscle cramps, neck pain

Frequency not reported: Muscle twitching, leg pain


Uncommon (0.1% to 1%): Blepharospasm, diplopia, optic ischemic neuropathy, blurred vision

Rare (less than 0.1%): Mydriasis, oculogyric crisis, activation of a latent Horner’s syndrome


Rare (less than 0.1%): Malignant melanoma

1. Cerner Multum, Inc. “UK Summary of Product Characteristics.” O 0

2. Cerner Multum, Inc. “Australian Product Information.” O 0

3. “Product Information. Parcopa (carbidopa-levodopa).” Schwarz Pharma, Mequon, WI.

4. “Product Information. Rytary (carbidopa-levodopa).” Impax Pharmaceuticals, Hayward, CA.

5. “Product Information. Sinemet CR (carbidopa-levodopa).” Dupont Pharmaceuticals, Wilmington, DE.

6. “Product Information. Duopa (carbidopa-levodopa).” AbbVie US LLC, North Chicago, IL.

7. “Product Information. Sinemet (carbidopa-levodopa).” DuPont Pharmaceuticals, Wilmington, DE.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

Medical Disclaimer

More about Sinemet (carbidopa / levodopa)

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7 Ways to Cope with the Side Effects of Parkinson’s Drugs

Prescription medication is one the primary ways to manage the symptoms of Parkinson’s disease. Several drugs can be used to delay the progression of this disease. You might need to take a combination of them to control your symptoms.

Although Parkinson’s drugs are considered safe, they can cause side effects. Some of these medications can also interact with other drugs you take.

Below is a list of common drug treatments for Parkinson’s disease, and their possible side effects.

Levodopa increases levels of the chemical dopamine in your brain. A lack of dopamine is what causes the jerky movements and other symptoms of Parkinson’s disease. Levodopa is usually combined with carbidopa, and it comes in both long-acting and short-acting forms (Rytary, Parcopa, Stalevo).

Side effects include:

  • vomiting
  • nausea
  • lightheadedness
  • appetite loss
  • low blood pressure
  • confusion
  • uncontrollable movements of the face, arms, legs, or torso (dyskinesia)

Dopamine agonists. These drugs mimic the effects of dopamine on the brain. They come in:

  • pill form — pramipexole (Mirapex) and ropinirole (Requip)
  • as a patch (Neupro)
  • as a short-acting injection — apomorphine (Apokyn)

Side effects include:

  • daytime sleepiness
  • hallucinations
  • confusion
  • ankle swelling
  • compulsive behaviors, such as gambling and overeating
  • dyskinesia

Amantadine (Symmetrel) is an antiviral drug that helps reduce Parkinson’s tremors. Amantadine extended release (Gocovri) is indicated to relieve dyskinesia (involuntary movement) caused by levodopa.

Common side effects of both forms include:

  • nausea
  • lightheadedness
  • trouble sleeping
  • confusion
  • hallucinations
  • ankle swelling

COMT inhibitors such as entacapone (Comtan) help levodopa’s effects last longer in your body. Side effects include:

  • worsening of levodopa side effects like dyskinesia
  • confusion
  • hallucinations
  • diarrhea
  • reddish-brown urine

Anticholinergics like trihexyphenidyl (Artane) and benztropine mesylate (Cogentin) help with tremors. Side effects include:

  • blurred vision
  • dry mouth
  • constipation
  • confusion
  • memory problems
  • hallucinations
  • inability to urinate

MAO-B inhibitors such as selegiline (Eldepryl, Zelapar) and rasagiline (Azilect) keep more dopamine in your brain. Possible side effects include:

  • nausea
  • trouble sleeping
  • hallucinations (when taken with levodopa/carbidopa)

Here are seven ways to cope with the side effects of Parkinson’s drugs:

1. Know what to expect

Each time you get a new prescription, ask your doctor and pharmacist what side effects the drug might cause. Then you’ll know what symptoms to look out for and report to your doctor. Also, find out whether any of the other drugs you take might interact with your Parkinson’s medication, so you can avoid taking them together.

2. Stay on track

Follow directions carefully to prevent side effects. Take the exact amount of medication your doctor prescribed, at the same time each day. Also, note whether you need to take the drug with or without food. If you have a hard time remembering to take your medication, or you sometimes take the wrong dose, use a pill organizer and smartphone reminder to keep you on track.

3. Eat a snack

Nausea and vomiting are two of the most common side effects when you first start taking levodopa/carbidopa. Eating plain, high-carbohydrate foods like crackers or toast can help relieve these symptoms.

4. Adjust your drug dose

Side effects like dyskinesia might be due to the amount of levodopa you’re taking. Ask your doctor if you can lower your dose enough to prevent side effects, but not so low that it stops controlling your Parkinson’s symptoms. It might take some trial and error to get the dose just right.

Another option is to switch to an extended-release form of dopamine. Because the drug releases more slowly into your blood, it prevents the dopamine spikes and valleys that can trigger dyskinesia.

You might also need to add more of a drug. For example, adding extra carbidopa to levodopa can cut down on nausea.

5. Change the timing

Sometimes you can prevent a drug’s side effects by changing the time of day you take it. For example, if a medication makes you sleepy, take it at night rather than in the morning. If a drug causes insomnia, take it in the morning or afternoon.

6. Try another treatment

Medication isn’t the only way to treat Parkinson’s disease. Deep brain stimulation (DBS) is a type of surgery used to treat Parkinson’s symptoms, like tremors and stiffness. Your doctor might recommend this procedure if you’ve had Parkinson’s for at least four years and you have dyskinesia. Having DBS can cut down on the amount of medication you have to take.

7. Talk to your doctor

If you do have side effects from your Parkinson’s drugs, report them to your doctor right away. Your doctor can help you manage them. For example, they may change your dose or switch you to another drug. Don’t stop taking any medication without first consulting with your doctor.


The most potent medication for Parkinson’s disease (PD) is levodopa. Its development in the late 1960s represents one of the most important breakthroughs in the history of medicine. Plain levodopa produces nausea and vomiting. It is combined with carbidopa to prevent this side effect. The well-known combined carbidopa/levodopa name brand formulation is called Sinemet®.

There are many different preparations and strengths of carbidopa/levodopa, including long-acting forms, a combined long and short-acting capsule called Rytary®, a formulation that dissolves in the mouth without water, called Parcopa®, and a combined formulation that includes the COMT inhibitor entacapone, called Stalevo®.

It is important that people with PD are aware which levodopa preparation they are taking because there are so many different pill sizes, strengths and manufacturers. Be careful when renewing prescriptions at the pharmacy because the accidental substitute of a different formulation may lead to an overdose or underdose.

Carbidopa/levodopa remains the most effective drug to treat PD. The addition of carbidopa prevents levodopa from being converted into dopamine prematurely in the bloodstream, allowing more of it to get to the brain. Therefore, a smaller dose of levodopa is needed to treat symptoms.

Some people with PD have been reluctant to take it, believing it to be a last resort. But most neurologists agree that delaying treatment too long is unwise and may put a person with PD at risk for falling and decreased optimal, consistent symptom benefit. The decision about when to start carbidopa/levodopa is different for every person with PD and requires consideration of potential benefits, risks and the availability of alternatives.

Unfortunately, with time, patients experience other side effects including dyskinesias (spontaneous, involuntary movements) and “on-off” periods when the medication will suddenly and unpredictably start or stop working. It is unclear whether this is a symptom of starting the medication at an advanced stage of PD or whether it is related to prolonged use of levodopa (although there is some published evidence for the former explanation). Check with a doctor before taking any of the following to avoid possible interactions: antacids, anti-seizure drugs, anti-hypertensives, anti-depressants and high protein food. The same drugs that interact with carbidopa/levodopa and entacapone interact with Stalevo®.

What are the facts?

  • The drug levodopa is synthesized in the brain into dopamine. It is the most important first-line drug for the management of Parkinson’s.
  • Levodopa is almost always given in combination with the drug carbidopa, which prevents the nausea that can be caused by levodopa alone. Carbidopa is also a levodopa enhancer. When added, carbidopa enables a much lower dose of levodopa (80 percent less) and helps reduce the side effects of nausea and vomiting. Pills containing both drugs are often labeled “carbidopa-levodopa,” with the active components listed in alphabetical order.
  • Levodopa in pill form is absorbed in the blood from the small intestine and travels through the blood to the brain, where it is converted into dopamine, needed by the body for movement.
  • Carbidopa-levodopa tablets are available in immediate-release and slow-release forms as well as dissolvable tablets that are placed under the tongue.
  • Carbidopa-levodopa immediate/extended release combination capsules (Rytary™) maintain levodopa concentrations longer than the immediate-release or other available oral levodopa formulations. Following an initial peak at about one hour, plasma levodopa concentrations are maintained for about four to five hours before declining. Clinical trials indicate that patients with motor fluctuations on other oral carbidopa-levodopa products may be able to switch to Rytary™ and experience a reduction in “off” time while requiring fewer medication administrations. Carbidopa/levodopa can be taken with or without food, but high fat meals may delay absorption. Dosages are not interchangeable with dosages other carbidopa-levodopa products. For more information relating to prescribing Rytary™, please see How to Dose Carbidopa and Levodopa Extended-Release Capsules (Rytary), by Dr. Robert A. Hauser of the University of South Florida, a Center of Excellence.
  • Carbidopa/levodopa is also now available via a dopamine intestinal infusion pump (DUOPA™), which provides 16 continuous hours of carbidopa and levodopa for motor symptoms. The small, portable infusion pump delivers carbidopa and levodopa directly into the small intestine. In a clinical trial, the amount of “on” time without troublesome dyskinesia was better in the pump group when compared to the placebo group (4.1 vs. 2.2 hours). One of the major drawbacks to the pump approach is the need for a percutaneous gastrojejunostomy (a small feeding tube). For more information relating to prescribing Duopa™, please see Carbidopa/Levodopa Enteral Suspension (Duopa) by Rajesh Pahwa, MD, and Kelly Lyons, PhD, of the University of Kansas, a Center of Excellence.

Common Side Effects

  • Nausea
  • Vomiting
  • Loss of appetite
  • Lightheadedness
  • Lowered blood pressure
  • Confusion
  • Dyskinesia (if used as a long-term therapy; between three to five years)
    • People who use levodopa long term may experience dyskinesia at some point, usually three to five years after starting the medication.
    • The term dyskinesia describes involuntary, erratic, writhing movements of the face, arms, legs, and/or trunk, which usually occur one to two hours after a dose of levodopa has been absorbed into the bloodstream and is having its peak clinical effect.

Uncommon Side Effects

  • Sleepiness, sudden onset sleep

Eating Proteins with Levodopa/Sinemet*

  • With more advanced PD, it is best to take Sinemet® 30 to 60 minutes before eating a meal. This allows for quick absorption before food can interfere.
  • Take the Sinemet® along with non-protein foods.
  • Ginger tea is a good choice for many people, because it often “settles the stomach”.
  • A graham or soda cracker along with ginger tea may help and are low in protein so should not interfere with the absorption of Sinemet®.
  • If you cannot tolerate Sinemet because of nausea, upset stomach, you may need to actually take it with food.

Caution: PD medications may have interactions with certain foods, other medications, vitamins, herbal supplements, over the counter cold pills and other remedies. Anyone taking a PD medication should talk to their doctor and pharmacist about potential drug interactions.


Available Doses

Initial Dosing

Side Effects*





10/100 mg

25/100 mg

25/100 mg
1/2-1 tablet

Nausea, vomiting, falling blood pressure upon standing, worsening of glaucoma, dyskinesia, hallucination, psychosis, low blood pressure, confusion, dyskinesia, dry mouth, dizziness

Treatment of motor symptoms in early and advanced PD

Dopamine receptor antagonists — certain psychiatric medications and anti-nausea drugs, nonselective monoamine oxidase inhibitors. Antacids and proteins taken in close proximity to the drug may reduce absorption.


Orally disintegrating tablet


10/100 mg

25/100 mg

25/250 mg

25/100 mg

Nausea, vomiting, falling blood pressure upon standing, worsening of glaucoma, dyskinesia, hallucination, psychosis, low blood pressure, confusion, dyskinesia, dry mouth, dizziness

Treatment of motor symptoms in early and advanced PD

Dopamine receptor antagonists — certain psychiatric medications and anti-nausea drugs, nonselective monoamine oxidase inhibitors. Antacids and proteins taken in close proximity to the drug may reduce absorption.


Controlled release

25/100 mg

50/200 mg

25/10.0 mg 2X/day

50/200 mg 2X/day

Nausea, vomiting, falling blood pressure upon standing, worsening of glaucoma, dyskinesia, hallucination, psychosis, low blood pressure, confusion, dyskinesia, dry mouth, dizziness

Treatment of motor symptoms in early and advanced PD

Dopamine receptor antagonists — certain psychiatric medications and anti-nausea drugs, nonselective monoamine oxidase inhibitors. Antacids and proteins taken in close proximity to the drug may reduce absorption.



12.5/50/200 mg

18.75/75/200 mg

25/100/200 mg

31.25/125/200 mg

37.5/150/200 mg

50/200/200 mg

12.5/50/200 mg

Nausea, vomiting, falling blood pressure upon standing, worsening of glaucoma, dyskinesia, hallucination, psychosis, dyskinesia, diarrhea, hyperkinesia, abdominal pain, dizziness, harmless discoloration of urine, saliva and/ or sweat

Secondary course of treatment; combines entacapone with levodopa/ carbidopa to block COMT (catechol-o-methyl transferase) enzyme and prolong levodopa’s effectiveness

Dopamine receptor antagonists — certain psychiatric medications and anti-nausea drugs, nonselective monoamine oxidase inhibitors. Antacids and proteins taken in close proximity to the drug may reduce absorption.


Extended-release capsules


23.75 mg / 95 mg

36.25 mg / 145 mg

48.75 mg / 195 mg

61.25 mg / 245 mg

For those first starting carbidopa/
levodopa, 36.25mg/145 mg 3 times daily; for those converting from another form of carbidopa/
levodopa, calculation based on prior therapeutic dose.

Nausea, vomiting, falling blood pressure upon standing, worsening of glaucoma, dyskinesia, hallucination, psychosis, dizziness, headache, insomnia, abnormal dreams, dry mouth, dyskinesia, anxiety, constipation, vomiting, and orthostatic hypotension Cardiovascular events possible in people with history of cardiovascular disease; hallucinations or psychosis: dyskinesia. May cause falling asleep during activities of daily living.

Secondary course of treatment for people with Parkinson’s disease who are experiencing disabling wearing-off periods.

Dopamine receptor antagonists — certain psychiatric medications and anti-nausea drugs, nonselective monoamine oxidase inhibitors. Antacids and proteins taken in close proximity to the drug may reduce absorption.


Enteral Suspension


(This is a gel formulation of the drug that requires a surgically-placed tube. Learn more here)

Levodopa 4.63/20 mg per mL of suspension (about 25/100 mg per teaspoon).

Dosing depends on conversion from the prior dose of carbidopa/
levodopa tablets to an equivalent daily dose of the suspension which is then delivered to the small intestine using a surgically inserted tube and a pump. The medication is pumped continuously over 16 hours each day.

Nausea, vomiting, falling blood pressure upon standing, worsening of glaucoma, dyskinesia, hallucination, psychosis. Complications of the device or surgery (movement or dislocation of the tube, infection, redness at the insertion point, pancreatitis, bleeding into the intestines, air or infection in the abdominal cavity, failure of the pump,) ankle swelling, high blood pressure, upper respiratory tract infection, mouth or throat pain, lung problems. May cause falling asleep during daily activities dyskinesias. hallucinations/
confusion; depression and suicidality; and damage to peripheral nerves.

For the treatment of motor fluctuations in advanced Parkinson’s disease.

Duopa is contraindicated for individuals taking nonselective monoamine oxidase (MAO) inhibitors. If taken with selective MAO-B inhibitors, it may cause orthostatic hypotension. If taken with antihypertensive drugs, it may cause symptomatic postural hypotension. Dopamine D2 receptor antagonists, isoniazid, iron salts, and high-protein diet may reduce drug effectiveness of Duopa.

* Please note that the side effects listed in the tables that accompany each class of medication are the most commonly experienced. Not all individuals will experience such side effects. For many people who do experience side effects, they can often be effectively limited or eliminated with careful adjustments to dosage or the timing of the individual doses.

Speak to the treating physician immediately if any side effects are experienced. For a complete description of each drug and its possible side effects, please request a “package insert” from your pharmacist for each drug used. It is recommended that all prescriptions be filled at the same pharmacy to avoid interactions between medications. Interactions can be dangerous and even life-threatening, so make sure the pharmacist knows of all medications and supplements being taken, including over-the-counter medications and supplements.

Page reviewed by Dr. Chauncey Spears, Movement Disorders Fellow at the University of Florida, a Parkinson’s Foundation Center of Excellence.

What should I discuss with my healthcare provider before taking carbidopa and levodopa?

You should not use carbidopa and levodopa if you are allergic to it, or if you have:

  • narrow-angle glaucoma.

Do not use carbidopa and levodopa if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

To make sure carbidopa and levodopa is safe for you, tell your doctor if you have:

  • heart disease, high blood pressure, history of heart attack;
  • liver or kidney disease;
  • an endocrine (hormonal) disorder;
  • asthma, chronic obstructive pulmonary disease (COPD), or other breathing disorder;
  • a stomach or intestinal ulcer;
  • open-angle glaucoma; or
  • a history of depression, mental illness, or psychosis.

People with Parkinson’s disease may have a higher risk of skin cancer (melanoma). Talk to your doctor about this risk and what skin symptoms to watch for.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Carbidopa and levodopa can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

The carbidopa and levodopa disintegrating tablet may contain phenylalanine. Talk to your doctor before using this form of carbidopa and levodopa if you have phenylketonuria (PKU).

How should I take carbidopa and levodopa?

If you already take levodopa, you must stop taking it at least 12 hours before you start taking carbidopa and levodopa.

Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Carbidopa and levodopa can be taken with or without food. Take your doses at regular intervals to keep a steady amount of the drug in your body at all times. Get your prescription refilled before you run out of medicine completely.

Do not crush, chew, break, or open a carbidopa and levodopa capsule. Swallow it whole.

The tablet is sometimes broken in half to give the correct dose. Always swallow a whole or half tablet without chewing or crushing.

To take the orally disintegrating tablet (Parcopa):

  • Keep the tablet in the bottle until you are ready to take it.
  • Use dry hands to remove the tablet and place it on your tongue.
  • Do not swallow the tablet whole. Allow it to dissolve in your mouth without chewing. Swallow several times as the tablet dissolves.

It may take up to several weeks of using carbidopa and levodopa before your symptoms improve. For best results, keep using the medication as directed. Talk with your doctor if your symptoms do not improve after a few weeks of treatment. Also tell your doctor if the effects of this medication seem to wear off quickly in between doses.

If you use this medicine long-term, you may need frequent medical tests at your doctor’s office.

This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using carbidopa and levodopa.

Do not stop using carbidopa and levodopa suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using carbidopa and levodopa.

Store at room temperature away from moisture, heat, and light.


Possible Interactions with: Phenylalanine

Also listed as:

Table of Contents > Supplement Interactions > Possible Interactions with: Phenylalanine

If you are currently being treated with any of the following medications, you should not use phenylalanine without first talking to your health care provider.

Monoamine Oxidase Inhibitors (MAOIs) — Monoamine oxidase inhibitors (MAOIs) are a class of rarely used antidepressants drugs including phenelzine (Nardil), isocarboxazid (Marplan), and tranylcypromine sulfate (Parnate). Phenylalanine supplementation may cause a severe increase in blood pressure in people taking these drugs. This severe increase in blood pressure (also called “hypertensive crisis”) can lead to a heart attack or stroke. For this reason, individuals taking MAOIs should avoid foods and supplements containing phenylalanine.

Baclofen — The absorption of baclofen (Lioresal), a medication used to relieve muscle spasms, may be reduced by phenylalanine. Therefore, it is best to avoid taking this medication with a meal, especially one that is high in protein content, or with phenylalanine supplements.

Levodopa — A few case reports suggest that phenylalanine may reduce the effectiveness of levodopa (Sinemet), a medication used to treat Parkinson’s disease. Some researchers speculate that phenylalanine may interfere with the absorption of this medication. Therefore, phenylalanine should not be taken at the same time as levodopa.

Selegiline — L-phenylalanine and the selective MAO inhibitor selegiline (Eldepryl, Deprenyl) may increase the antidepressant effects of phenylalanine. Therefore, phenylalanine should not be taken at the same time as selegine.

Neuroleptic drugs — L-phenylalanine may enhance the tardive dyskinesia side effects of neuroleptic drugs, such as phenytoin (Dilantin), valproid acid (Depakene, Depakote), or carbamazepine (Tegretol), if used together. Therefore, phenylalanine should not be taken at the same time as neuroleptic drugs.

A Critical Reappraisal of the Worst Drugs in Parkinson’s Disease

What are the worst drugs for Parkinson’s disease patients? Couldn’t a simple list be assembled and disseminated to the Parkinson community? Recently Ed Steinmetz, an experienced neurologist in Ft. Meyers, FL pointed out to me, a list approach published in the Public Citizen Newsletter ( The approach was to list every drug associated with a single confirmed or unconfirmed symptom of Parkinson’s disease or parkinsonism. Parkinson’s disease is defined as a neurodegenerative syndrome (common symptoms include tremor, stiffness, slowness, posture and gait issues), whereas parkinsonism encompasses a wider net of drug induced and other potential causes. In parkinsonism symptoms are similar to Parkinson’s disease, but patients do not have Parkinson’s disease. Patients and family members confronted with a simple “drug list” approach may falsely conclude that most medicines are bad for Parkinson’s disease, and that any medicine may cause parkinsonism. This concept is in general, incorrect. Although the approach is well-meaning, it is in need of a major revision, as Parkinson’s disease and parkinsonism are too complex to summarize by simple lists. In this month’s column I will try to summarize the key information that patients and family members need to know about the “worst pills,” for Parkinson’s disease and parkinsonism.

It is well known that drugs that block dopamine worsen Parkinson’s disease and also worsen parkinsonism, whereas dopamine replacement therapy (Carbidopa/Levodopa, Sinemet) may improve symptoms. One of the big issues facing many Parkinson’s disease patients is psychosis (hallucinations, illusions, and behavioral changes such as paranoia). How does one concomitantly administer dopamine replacement therapy, which may in some cases induce psychosis, and at the same time administer dopamine blocker drugs aimed at alleviating psychosis? Will the drugs cancel each other out? There are two dopamine blockers that will not cancel out dopamine replacement, and therefore not appreciably worsen Parkinson’s disease. One is Quetiapine (Seroquel), and the other is Clozapine (Clozaril). Clozapine is the more powerful of the two drugs, but it requires weekly blood monitoring. Other classical dopamine blocking drugs, also referred to as neuroleptics (e.g. Haldol), worsen Parkinson’s disease and parkinsonism.

Patients may not be aware that some common drugs used for conditions such as headache or gastrointestinal dysmotility may also block dopamine, and concomitantly worsen Parkinson’s disease, or alternatively result in parkinsonism. These drugs include Prochlorperazine (Compazine), Promethazine (Phenergan), and Metoclopramide (Reglan). They should be avoided. Also, drugs that deplete dopamine such as reserpine and tetrabenazine may worsen Parkinson’s disease and parkinsonism and should be avoided in most cases. Substitute drugs that do not result in worsening of parkinsonism can be utilized, and these include Ondansetron (Zofran) for nausea, and erythromycin for gastrointestinal motility.

Antidepressants, anxiolytics, mood stabilizers, thyroid replacement drugs, and antihypertensives are in general safe, and do not worsen Parkinson’s disease and parkinsonism. They appear commonly on lists such as that provided by the Public Citizen, but these lists are misleading. There may be rare reactions that lead to worsening of Parkinson’s disease or parkinsonism with these drugs, but these are very rare occurrences. The bigger issue is drug-drug interactions. The most commonly encountered in Parkinson’s disease is mixing a MAO-B Inhibitor (Selegline, Rasagiline, Azilect, Zelapar, Selegiline Hydrochloride Dissolvable) with a pain medicine such as Meperidine (Demerol). Also, MAO-A Inhibitors (e.g. Pirlindole) should not be taken with antidepressants. And finally it should be kept in mind that in rare instances mixing an antidepressant with another class of drugs can in select cases result in a serotonin syndrome. Finally, remember, there are very common “other” side effects of antidepressants, anxiolytic drugs, mood stabilizers, thyroid replacement drugs, and antihypertensives.

In summary, the list approach to the worst pills in Parkinson’s disease and parkinsonism needs a critical reappraisal. A more refined approach would take into consideration the complexities of Parkinson’s disease and parkinsonism, and would appreciate that with physician guidance, and with few exceptions, most drugs can be safely and effectively administered in Parkinson’s disease and parkinsonism.

*Portions of this post have previously appeared on Dr. Okun NPF What’s Hot in Parkinson’s Treatment blog.

A Florida Parkinson’s Treatment Blog by Michael S. Okun, M.D.

UF Center for Movement Disorders & Neurorestoration, Gainesville FL

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