Carbidopa | Side Effects, Dosage, Uses & More
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Generic Name:

carbidopa, Oral tablet

All Brands

  • Lodosyn
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Highlights for carbidopa

Oral tablet
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Carbidopa is used to treat the symptoms of Parkinson’s disease and parkinsonism (Parkinson’s-like symptoms) that may develop after encephalitis (swelling of the brain) called postencephalitic parkinsonism or injury to the nervous system due to carbon monoxide or manganese poisoning or both called symptomatic parkinsonism.

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This drug shouldn’t be taken by itself. It should be taken with the combination drug carbidopa/levodopa or with levodopa.

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This drug should be taken by mouth and comes as a tablet.

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When this drug is used in combination with levodopa or carbidopa-levodopa combination products, the most common adverse reaction is dyskinesia (involuntary movements) and nausea.

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This drug is available as a generic drug.
IMPORTANT INFORMATION

Sleepiness or drowsiness

This medication has caused patients to fall asleep without warning during the day while doing regular activity such as driving.

Hyperthermia (high fever) and confusion.

Serious effects from this medication including high fever, confusion, rapid heart rate, and sweating can occur when the dose is lowered. It also can happen when the drug is stopped suddenly, especially in people who also take mood stabilizers. This group of symptoms can be a sign of a serious condition called neuroleptic malignant syndrome.

What is carbidopa?

Carbidopa is prescription drug. It’s available as an oral tablet. It’s also available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in all strengths or forms as the brand-name version. Talk to your doctor to see if the generic version will work for you.

This drug is used in combination therapy. You must take this drug with either the combination drug carbidopa/levodopa or with levodopa.

Why it's used

This drug is used to help make more of the levodopa that you take to help relieve symptoms of Parkinson's disease available to your brain without taking higher doses of levodopa.

How it works

This drug belongs to a class of drugs called aromatic amino acid decarboxylase inhibitors. A class of drugs is a group of medications that work in a similar way.

More Details

How it works

This drug belongs to a class of drugs called aromatic amino acid decarboxylase inhibitors. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

Symptoms of Parkinson's disease and parkinsonism are related to having less than normal amounts of the chemical dopamine in your brain. The drug levodopa is prescribed to people with Parkinson’s disease and parkinsonism because this drug is converted to dopamine in your brain. Carbidopa stops the breakdown of levodopa in your body, making more of the levodopa that you take available to your brain.

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carbidopa Side Effects

Oral tablet

More Common Side Effects

Some of the more common side effects that can occur with the use of this drug with levodopa or carbidopa-levodopa products include:

  • nausea

  • discolored saliva, urine, and sweat (red, brown, or black)

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

Call your doctor right away if you have serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Skin cancer (melanoma). It’s unclear whether the risk of skin cancer is due to Parkinson’s disease or the drugs that are used to treat the disease.

Pharmacist's Advice
Healthline Pharmacist Editorial Team
This drug may cause drowsiness.
Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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carbidopa May Interact with Other Medications

Oral tablet

Carbidopa can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Food interactions

Foods that are high in protein may reduce the amount of carbidopa that is absorbed by your body.

Medications that might interact with this drug

Blood pressure drugs

Taking carbidopa with blood pressure drugs may cause a drop in your blood pressure when you stand, which can cause dizziness. Examples of these drugs include:

  • carvedilol
  • metoprolol
  • lisinopril
  • hydrochlorothiazide
  • amlodipine
  • valsartan
  • losartan
  • clonidine

Depression drugs

Certain drugs used to treat depression called nonselective monoamine oxidase inhibitors (MAOIs) shouldn’t be taken with carbidopa. Taking these drugs together could cause your blood pressure to increase to dangerously high levels, putting you at risk of a stroke. This is a medical emergency. Examples of these depression drugs include:

  • phenelzine
  • isocarboxazid
  • tranylcypromine

Mood stabilizing drugs

Taking carbidopa with certain mood stabilizers may cause changes in your blood pressure and involuntary movements. Examples of these medicines include:

  • selegiline
  • amitriptyline

Drugs to improve stomach function

The use of the drug metoclopramide may reduce the effect of carbidopa.

Tuberculosis drugs

Taking isoniazid with carbidopa may cause your blood pressure to increase or become unstable.

Supplements

Taking iron supplements or multivitamins containing iron may reduce the effect of carbidopa.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Carbidopa warnings
People who have had stomach ulcers
People who have had stomach ulcers

If you have had stomach ulcers, taking carbidopa may cause your stomach to bleed.

Pregnant women
Pregnant women

Carbidopa is a category C pregnancy drug. That means two things:

  1. Research in animals has shown adverse effects to the fetus when the mother takes the drug.
  2. There haven’t been enough studies done in humans to be certain how the drug might affect the fetus.

Talk to your doctor if you’re pregnant or planning to become pregnant. This drug should be used only if the potential benefit justifies the potential risk to the fetus.

Women who are breast-feeding
Women who are breast-feeding

It’s not known whether carbidopa passes into breast milk.

Talk to your doctor if you breast-feed your child. You may need to decide whether to stop breast-feeding or stop taking this medication.

For children
For children

This drug shouldn’t be used in people younger than 18 years.

Allergies
Allergies

Carbidopa can cause a severe allergic reaction. Symptoms can include:

  • extreme swelling around eyes or lips (angioedema)
  • hives
  • itching
  • inflammation and bleeding in the small blood vessels of your skin
  • the formation of blisters called bullous lesions

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

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How to Take carbidopa (Dosage)

Oral tablet

All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Parkinson’s disease

Generic: carbidopa

Form: Oral tablet
Strengths: 25 mg

Brand: Lodosyn

Form: Oral tablet
Strengths: 25 mg
Adult dosage (ages 18 years and older):
  • The usual starting dose of carbidopa is 25 mg, taken three or four times per day.
  • You should take carbidopa the same time you take your levodopa/carbidopa.
  • Your daily dose of carbidopa shouldn’t be greater than 200 mg.
Child dosage (ages 0–17 years):

This medication hasn’t been studied in children. It shouldn’t be used in people younger than 18 years.

Postencephalitic parkinsonism

Generic: carbidopa

Form: Oral tablet
Strengths: 25 mg

Brand: Lodosyn

Form: Oral tablet
Strengths: 25 mg
Adult dosage (ages 18 years and older):
  • The usual starting dose of carbidopa is 25 mg, taken three or four times per day.
  • You should take carbidopa the same time you take your levodopa/carbidopa.
  • Your daily dose of carbidopa shouldn’t be greater than 200 mg.
Child dosage (ages 0–17 years):

This medication hasn’t been studied in children. It shouldn’t be used in people younger than 18 years.

Symptomatic parkinsonism

Generic: carbidopa

Form: Oral tablet
Strengths: 25 mg

Brand: Lodosyn

Form: Oral tablet
Strengths: 25 mg
Adult dosage (ages 18 years and older):
  • The usual starting dose of carbidopa is 25 mg, taken three or four times per day.
  • You should take carbidopa the same time you take your levodopa/carbidopa.
  • Your daily dose of carbidopa shouldn’t be greater than 200 mg.
Child dosage (ages 0–17 years):

This medication hasn’t been studied in children. It shouldn’t be used in people younger than 18 years.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Carbidopa comes with risks if you don’t take it as prescribed.

If you stop taking the drug or don’t take it at all

You may experience a high fever and confusion if you stop taking carbidopa suddenly, especially if you’re taking certain psychiatric medication.

If you miss doses or don’t take the drug on schedule

If you miss doses or don’t take carbidopa on schedule, it may not work as well or may stop working completely. For this drug to work well, a certain amount needs to be in your body at all times.

If you take too much

If you take too much, you could have nausea, vomiting, diarrhea, and high blood pressure.

What to do if you miss a dose

Take your dose as soon as you remember. But if you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working

Your symptoms of Parkinson’s disease or parkinsonism will become more controlled. Sometimes Parkinson’s symptoms may appear a few hours after you take the medication. This is called a wearing-off effect. Please notify your physician should this become a problem.

Carbidopa is used for long-term treatment.

You may take carbidopa with or without food

If you take it with food, take it with food that is low in protein. Protein prevents your body from absorbing carbidopa.

Store this drug carefully

  • Store carbidopa at room temperature between 59ºF and 86°F (15ºC and 30°C). Keep it away from high temperatures.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

A prescription for this medication is refillable

You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

You’ll need to be monitored for signs and symptoms of Parkinson’s disease to tell if your medication is working.

For safety, the following may be monitored using blood tests:

  • Liver function
  • Renal function
  • Complete blood count

Skin examinations may also be done to monitor for side effects

Your diet

Foods that are high in protein may delay the absorption of levodopa and may reduce the amount taken up in the body.

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

What does the pill look like?

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How Much Does carbidopa Cost?

Oral tablet

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Lowest price for carbidopa

Walmart $203.86
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Rite-Aid $401.23
These prices represent the lowest priced national pharmacies for carbidopa on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for carbidopa on GoodRx. They may be lower than your insurance.

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on November 30, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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