Skip to main content

Carbidopa Dosage

Medically reviewed by Last updated on Jun 14, 2021.

Applies to the following strengths: 25 mg

Usual Adult Dose for Parkinsonian Tremor

Patients on carbidopa-levodopa therapy requiring additional carbidopa:
Initial dose: 25 mg orally with the first dose of carbidopa-levodopa each day
Maintenance dose: Additional doses of 12.5 mg or 25 mg may be given with each dose of carbidopa-levodopa
Maximum dose: 200 mg orally per day

Patients requiring individual titration of carbidopa and levodopa:
Initial dose: 25 mg orally 3 to 4 times a day, given at the same time as levodopa
Maximum dose: 200 mg orally per day

-Most patients respond to a 1:10 proportion of carbidopa and levodopa, provided the daily dosage of carbidopa is 70 mg or more a day; for patients taking carbidopa-levodopa, the amount of carbidopa in carbidopa-levodopa should be considered when calculating the maximum daily carbidopa dose.
-In patients already on levodopa, allow 12 hours between the last dose of levodopa and the initiation of therapy with carbidopa and levodopa.

Uses: With carbidopa-levodopa or with levodopa in the treatment of symptoms of idiopathic Parkinson's disease (paralysis agitans), postencephalitic parkinsonism, and symptomatic parkinsonism

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

Dose reduction may be required if there is occurrence of involuntary movements.

Concomitant levodopa:
-If levodopa and carbidopa are titrated individually, levodopa should be initiated at 20% to 25% of the previous or recommended daily dosage of levodopa when taken alone.


-Hypersensitivity to active substance or any other product ingredient
-Current or recent (within the previous 14 days) use of nonselective monoamine oxidase (MAO) inhibitors; may be administered concomitantly with the manufacturer's recommended dose of an MAO inhibitor with selectivity for MAO type B (e.g., selegiline HCl)
-Narrow-angle glaucoma

Consult WARNINGS section for additional precautions.

Safety and efficacy have not been established in patients younger than 18 years.


Data not available

Other Comments

-If the patient is taking carbidopa-levodopa, the amount of carbidopa in carbidopa-levodopa should be considered when calculating the total daily dose.
-Blepharospasm may be used as an early sign of excess dosage in some patients.
-Therapeutic and adverse responses occur more rapidly with concomitant carbidopa and levodopa compared with levodopa given alone.
-Patients should be carefully monitored for signs and symptoms of neuroleptic malignant syndrome if treatment is abruptly reduced or discontinued.

-Periodic evaluations of hepatic, hematopoietic, cardiovascular, and renal function.
-Psychiatric: Development of new or increased gambling urges, sexual urges, or other intense urges.

Patient advice:
-Occasionally dark color may appear in saliva, urine, or sweat after ingestion of carbidopa.
-A change in diet to high-protein foods may delay the absorption of levodopa.
-Carbidopa-levodopa therapy may lead to sudden onset of sleep during daily activities or somnolence. Avoid driving or operating machinery if you experience these symptoms.

Frequently asked questions

Further information

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