PlainMeds provides educational information only. This is not medical advice. Always consult your doctor or pharmacist.

Prescription medication · Dopamine Precursor Combination

carbidopa/levodopa

Also sold as Sinemet. This medicine treats Parkinson's disease.

Data updated 2026-05-15

28,176
FDA reports
13
InteractionsSeveral interactions
$1.29
Brand price (NADAC)

What the data shows

carbidopa/levodopa (Sinemet) is a prescription Dopamine Precursor Combination, with 28,176 FDA adverse-event reports on file, with 13 documented drug interactions.

Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.

carbidopa/levodopa (Sinemet) is a prescription Dopamine Precursor Combination. This medicine treats Parkinson's disease.

This medicine contains carbidopa, levodopa, and entacapone. It is used to treat Parkinson's disease.

Verify with FDA → · CMS NADAC pricing →

Drug Pricing (NADAC)

Brand Price

$1.29/unit

Generic Available

No

ORGANON

Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →

View Alternatives → Compare with Another Drug →

What it does

This medicine treats Parkinson's disease.

Common side effects

Uncontrolled movements, Diarrhea, Nausea

Key warnings

This medicine can make you fall asleep suddenly, even when you feel awake.

The sections below are summarized in plain English from carbidopa/levodopa's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

How It Works

Levodopa turns into dopamine in your brain, helping to control movement. Carbidopa helps levodopa get to your brain. Entacapone helps levodopa work longer.

How to Take It

Take this medicine exactly as your doctor tells you. Do not split or crush the tablets. The right dose varies for each person. Your doctor may change your dose to find what works best for you.

This is a plain-language summary of carbidopa/levodopa's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.

Pregnancy & Breastfeeding

This medicine may harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if this medicine passes into breast milk.

This is a plain-language summary of carbidopa/levodopa's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.

This is a plain-language summary of carbidopa/levodopa's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.

Storage

Store at room temperature, away from heat and moisture.

Side Effects (from patient reports)

Based on 28,176 FDA adverse event reports.

Most-reported reactions

Adverse reactions in FAERS for carbidopa/levodopa, by number of reports

reports

What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.

Source FDA Adverse Event Reporting System (FAERS)

Serious Warnings

This medicine can make you fall asleep suddenly, even when you feel awake. Be careful when driving or doing other activities where you need to be alert. Stopping this medicine suddenly can cause serious problems like fever and confusion.

Known Drug Interactions

moderate warfarin

7 DRUG INTERACTIONS Drugs metabolized by COMT: use with caution ( 5.10 , 7.2 ) Anti-hypertensive agents: dose adjustment may be required ( 7.3 ) Tricyclic antidepressants: risk of hypertension and dyskinesia reported during concomitant use with carbidopa/levodopa ( 7.4 ) Dopamine D2 receptor antagonists, isoniazid, phenytoin, papaverine and iron salts: may reduce efficacy of carbidopa, levodopa and entacapone tablets ( 7.5 , 7.6 , 7.7 , 7.8 , 7.9 ) Drugs that interfere with biliary excretion, glucuronidation and intestinal beta-glucuronidase: dose adjustment of carbidopa, levodopa and...

Mechanism: These drugs can interfere with how your body breaks down certain medicines, which may change how well your blood thinner works.

What to do: Your doctor should check your blood clotting tests more frequently and may need to adjust your warfarin dose.

moderate entacapone

7 DRUG INTERACTIONS Drugs metabolized by COMT: use with caution ( 5.10 , 7.2 ) Anti-hypertensive agents: dose adjustment may be required ( 7.3 ) Tricyclic antidepressants: risk of hypertension and dyskinesia reported during concomitant use with carbidopa/levodopa ( 7.4 ) Dopamine D2 receptor antagonists, isoniazid, phenytoin, papaverine and iron salts: may reduce efficacy of carbidopa, levodopa and entacapone tablets ( 7.5 , 7.6 , 7.7 , 7.8 , 7.9 ) Drugs that interfere with biliary excretion, glucuronidation and intestinal beta-glucuronidase: dose adjustment of carbidopa, levodopa and...

Mechanism: Entacapone is designed to block the enzyme that breaks down levodopa, which helps the medicine stay in your system longer. This can increase the effects of the levodopa on your brain and body.

What to do: Use this combination with caution as directed by your doctor. Your healthcare provider may need to adjust your dose to prevent side effects.

moderate methyldopa

7.2 Drugs Metabolized by Catechol-O-Methyltransferase (COMT) Drugs known to be metabolized by COMT, such as isoproterenol, epinephrine, norepinephrine, dopamine, dobutamine, alpha-methyldopa, apomorphine, isoetherine, and bitolterol should be administered with caution in patients receiving entacapone regardless of the route of administration (including inhalation), as their interaction may result in increased heart rates, possibly arrhythmias, and excessive changes in blood pressure [ see Warnings and Precautions (5.10) ].

Mechanism: Both of these drugs are processed by the same enzyme in the body. Taking them together can cause the drugs to build up, which may lead to a fast heart rate or changes in blood pressure.

What to do: Use these medicines together with caution. Your doctor should monitor your heart rate and blood pressure closely during treatment.

moderate dobutamine

7.2 Drugs Metabolized by Catechol-O-Methyltransferase (COMT) Drugs known to be metabolized by COMT, such as isoproterenol, epinephrine, norepinephrine, dopamine, dobutamine, alpha-methyldopa, apomorphine, isoetherine, and bitolterol should be administered with caution in patients receiving entacapone regardless of the route of administration (including inhalation), as their interaction may result in increased heart rates, possibly arrhythmias, and excessive changes in blood pressure [ see Warnings and Precautions (5.10) ].

Mechanism: These drugs are broken down by the same enzyme, so taking them at the same time can lead to higher drug levels. This can cause dangerous changes in blood pressure or an irregular heartbeat.

What to do: Your doctor should use caution when giving these drugs together. They will likely monitor your heart rhythm and blood pressure for any problems.

moderate dopamine

7 DRUG INTERACTIONS Drugs metabolized by COMT: use with caution ( 5.10 , 7.2 ) Anti-hypertensive agents: dose adjustment may be required ( 7.3 ) Tricyclic antidepressants: risk of hypertension and dyskinesia reported during concomitant use with carbidopa/levodopa ( 7.4 ) Dopamine D2 receptor antagonists, isoniazid, phenytoin, papaverine and iron salts: may reduce efficacy of carbidopa, levodopa and entacapone tablets ( 7.5 , 7.6 , 7.7 , 7.8 , 7.9 ) Drugs that interfere with biliary excretion, glucuronidation and intestinal beta-glucuronidase: dose adjustment of carbidopa, levodopa and...

Mechanism: These medications compete for the same enzyme that clears them from your body. This can cause the drugs to reach high levels, potentially leading to heart rhythm issues or blood pressure spikes.

What to do: Use this combination with extreme caution. Your healthcare provider may need to adjust your doses and monitor your heart health closely.

Check all your medications →

This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.

Common Questions

Can I drive while taking this medicine?
Be careful. This medicine can cause sleepiness or sudden sleep attacks.
What should I do if I feel dizzy?
Stand up slowly. Dizziness can be a side effect of this medicine.
Can I drink alcohol while taking this medicine?
Talk to your doctor. Alcohol may worsen some side effects.
Will this medicine cure my Parkinson's disease?
No, this medicine helps manage the symptoms of Parkinson's disease, but it is not a cure.
How long does it take for this medicine to start working?
It may take a few weeks to see the full benefits of this medicine.
Can I stop taking this medicine on my own?
No, do not stop taking this medicine without talking to your doctor first. Stopping suddenly can cause serious problems.
What if I have side effects?
Tell your doctor about any side effects you experience.
Can I take other medicines with this one?
Tell your doctor about all the medicines you take, including over-the-counter drugs and supplements.
What should I do if my symptoms get worse?
Contact your doctor if your Parkinson's symptoms worsen.
How many tablets can I take each day?
The maximum number of tablets depends on the strength. Do not take more than your doctor prescribes.
What are the common side effects of carbidopa/levodopa?
The most commonly reported side effects of carbidopa/levodopa include Uncontrolled movements, Diarrhea, Nausea, Belly pain, Vomiting. Based on 28,176 FDA adverse event reports. Always consult your healthcare provider about potential side effects.
Does carbidopa/levodopa interact with other medications?
Yes, carbidopa/levodopa has 13 known drug interactions. Notable interactions include warfarin, entacapone, methyldopa. Always inform your doctor about all medications you are taking.
What drug class is carbidopa/levodopa?
carbidopa/levodopa belongs to the Dopamine Precursor Combination drug class. It requires a prescription (Rx). This medicine treats Parkinson's disease.
Is carbidopa/levodopa safe during pregnancy?
This medicine may harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. Always consult your healthcare provider before using any medication during pregnancy or breastfeeding.

Related Medications in Dopamine Precursor Combination

Other drugs grouped near carbidopa/levodopa - same-class peers and common alternatives.

acamprosate

Campral

Acamprosate is a medicine that can help you stay away from alcohol if you are alcohol-dependent and have already stopped drinking.

Compare with carbidopa/levodopa →

alprazolam

Xanax

Alprazolam (Xanax) is a medication that can help you with anxiety and panic disorders.

Compare with carbidopa/levodopa →

amitriptyline

Elavil

Amitriptyline is a medicine used to treat depression.

Compare with carbidopa/levodopa →

amphetamine/dextroamphetamine

Adderall, Adderall XR

Adderall XR is a stimulant medicine.

Compare with carbidopa/levodopa →

aripiprazole

Abilify

Aripiprazole (Abilify) is a medicine used to treat certain mental disorders and mood problems.

Compare with carbidopa/levodopa →

Compare carbidopa/levodopa vs acamprosate side-by-side →

Medication Guides

Understanding Drug Interactions

How CYP450 enzymes, inhibitors, and inducers affect your medications

Generic vs Brand Name Drugs

FDA requirements, cost savings, and when the difference matters

Narrow Therapeutic Index Drugs

Why some drugs demand precise dosing and monitoring

Common Drug Interactions

Dangerous medication combinations and how to protect yourself

Save on carbidopa/levodopa

Compare prices and find discounts at pharmacies near you. Free coupons can save up to 80% on prescriptions.

Check Prices on GoodRx →

Disclosure: This link may earn us a commission at no extra cost to you. See our terms.

What the FDA Data Shows for carbidopa/levodopa

The FDA label for carbidopa/levodopa (sold under brand names such as Sinemet) classifies it as a prescription-only medication in the Dopamine Precursor Combination class. This medicine treats Parkinson's disease. Official labeling lists 7 commonly reported side effects, including Uncontrolled movements, Diarrhea, Nausea.

Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 28,176 voluntary reports. The database also lists 13 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS.

Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.

Data Sources

Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).

FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.

Last updated: November 5, 2025

Read our methodology - how this data is sourced, computed, and verified.

Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.

All federal data sources used on this page