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.

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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 →

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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.

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.

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.

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.

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.

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.

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This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.

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 registry lists Uncontrolled movements, Diarrhea, Nausea, Belly pain, Vomiting among the most-reported FAERS reaction terms for carbidopa/levodopa. The compiled record contains 28,176 FDA adverse-event reports. These counts are not an individual symptom assessment.
Does carbidopa/levodopa interact with other medications?
The registry has 13 documented interaction rows for carbidopa/levodopa. Notable source-record pairings include warfarin, entacapone, methyldopa. These rows are not a complete medication review.
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.
What pregnancy or breastfeeding source fields are listed for carbidopa/levodopa?
The FDA label for carbidopa/levodopa contains product-specific pregnancy or breastfeeding language. PlainMeds does not apply that source text to an individual.

Related Medications in Dopamine Precursor Combination

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

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alprazolam

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amphetamine/dextroamphetamine

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aripiprazole

Abilify

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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 are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.

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. This registry does not provide medication decisions.

Last updated: November 5, 2025

PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.

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 from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.

All federal data sources used on this page