Carbidopa Side Effects

Not all side effects for carbidopa may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to carbidopa: oral tablet

Carbidopa alone is not associated with side effects. The following side effects are generally associated with carbidopa and levodopa therapy.

If you experience any of the following serious side effects, stop taking carbidopa and levodopa and seek emergency medical attention or contact your doctor immediately:

  • an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives);

  • uncontrolled movements of a part of the body;

  • seizures;

  • persistent nausea, vomiting, or diarrhea;

  • an irregular heartbeat or fluttering in your chest;

  • unusual changes in mood or behavior; or

  • depression or suicidal thoughts.

Other, less serious side effects may be more likely to occur. Continue to take carbidopa and levodopa and talk to your doctor if you experience

  • mild nausea, vomiting, or decreased appetite;

  • constipation, dry mouth, or blurred vision;

  • hand tremor;

  • muscle twitches;

  • dizziness or drowsiness;

  • insomnia, confusion, or nightmares;

  • agitation or anxiety;

  • darkening of urine or sweat; or

  • fatigue.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to carbidopa: compounding powder, oral tablet


In general, side effects have not been observed when carbidopa is administered alone. All side effects listed have been reported during concomitant use with levodopa or with carbidopa-levodopa therapy. The most common side effects included dyskinesias and nausea.[Ref]

Nervous system

Frequency not reported: bradykinetic episodes ("on-off" phenomenon), dizziness, headache, paresthesia, peripheral neuropathy, somnolence, and convulsions.[Ref]

A causal relationship with concomitant carbidopa and levodopa and the reported side effect of convulsions has not been established.[Ref]


Psychiatric side effects were reported with concomitant administration of levodopa or carbidopa-levodopa.[Ref]

Frequency not reported: Psychotic episodes (including delusions, hallucinations and paranoid ideation), agitation, confusion, dream abnormalities (including nightmares), insomnia, depression with or without development of suicidal tendencies, dementia, pathological gambling, increased libido (including hypersexuality), and impulse control symptoms.[Ref]


Frequency not reported: Cardiac irregularities, hypertension, myocardial infarction, hypotension (including orthostatic hypotension), palpitation, phlebitis, syncope, and chest pain.[Ref]


Frequency not reported: Nausea, abdominal pain and distress, anorexia, bruxism, burning sensation of the tongue, constipation, dark saliva, development of duodenal ulcer, diarrhea, dry mouth, dyspepsia, dysphagia, flatulence, gastrointestinal bleeding, gastrointestinal pain, heartburn, hiccups, sialorrhea, taste alterations, and vomiting.[Ref]


Frequency not reported: Hemolytic and nonhemolytic anemia, leukopenia, thrombocytopenia, agranulocytosis, decreased hemoglobin and hematocrit, decreased white blood cell count, and abnormal Coombs test.[Ref]


Frequency not reported: Angioedema[Ref]


Frequency not reported: Edema, weight gain, weight loss, abnormal lactic dehydrogenase, elevated serum glucose, and elevated serum potassium.[Ref]


Frequency not reported: Back pain, leg pain, muscle cramps, shoulder pain, dyskinesias such as choreiform, dystonic, and other involuntary movements.[Ref]


Frequency not reported: Upper respiratory infection, dyspnea, pharyngeal pain, cough, and bizarre breathing patterns.[Ref]


Frequency not reported: Flushing, increased sweating, malignant melanoma, alopecia, dark sweat, rash, urticaria, pruritus, Henoch-Schonlein purpura, and bullous lesions (including pemphigus-like reactions).[Ref]


Frequency not reported: Oculogyric crises, diplopia, blurred vision, and dilated pupils.[Ref]


Frequency not reported: Priapism, dark urine, urinary frequency, urinary incontinence, urinary retention, and urinary tract infection.[Ref]


Symptoms related to neuroleptic malignant syndrome are characterized by fever or hyperthermia. Other findings include neurological symptoms such as muscle rigidity, involuntary movements, altered consciousness, mental status changes, other disturbances such as autonomic dysfunction, tachycardia, tachypnea, sweating, hyper- or hypotension, and laboratory findings such as elevated creatine phosphokinase, leukocytosis, myoglobinuria, and increased serum myoglobin.[Ref]

Frequency not reported: Neuroleptic malignant syndrome, hoarseness, hot flashes, malaise, faintness, asthenia, fatigue, and sense of stimulation.[Ref]


Frequency not reported: Abnormalities in alkaline phosphatase, SGOT (AST), SGPT (ALT), and bilirubin.[Ref]


Frequency not reported: Abnormal blood urea nitrogen (BUN), increased serum creatinine and uric acid, white blood cells, bacteria and blood in the urine, protein and glucose in the urine.[Ref]


1. "Product Information. Lodosyn (carbidopa)" DuPont Pharma, Wilmington, DE.

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