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Lodosyn Side Effects

Generic Name: carbidopa

Note: This page contains information about the side effects of carbidopa. Some of the dosage forms included on this document may not apply to the brand name Lodosyn.

For the Consumer

Applies to carbidopa: oral tablet

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

The following side effects may occur when carbidopa (the active ingredient contained in Lodosyn) is taken with levodopa.

Call your doctor at once if you have:

  • uncontrolled muscle movements in your face (chewing, lip smacking, frowning, tongue movement, blinking or eye movement);

  • worsening of tremors (uncontrolled shaking);

  • severe nausea, vomiting, or diarrhea;

  • confusion, hallucinations, unusual changes in mood or behavior;

  • depression or suicidal thoughts;

  • seizure (convulsions); or

  • severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Some people taking carbidopa with levodopa have fallen asleep during normal daytime activities such as working, talking, eating, or driving. Tell your doctor if you have any problems with daytime sleepiness or drowsiness.

You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking this medicine. Talk with your doctor if this occurs.

You may notice that your sweat, urine, or saliva appears dark in color, such as red, brown, or black. This is not a harmful side effect, but it may cause staining of your clothes or bed sheets.

Common side effects may include:

  • nausea, upset stomach;

  • headache, dizziness;

  • sleep problems (insomnia), dreaming more than usual;

  • dry mouth, burning feeling in your tongue;

  • weight changes; or

  • abnormal liver function tests.

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 (the active ingredient contained in Lodosyn) 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

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.

A causal relationship with concomitant carbidopa (the active ingredient contained in Lodosyn) and levodopa and the reported side effect of convulsions has not been established.[Ref]

Frequency not reported: Bradykinetic episodes ("on-off" phenomenon), convulsions, dizziness, dyskinesias such as choreiform, dystonic and other involuntary movements, headache, neuroleptic malignant syndrome, oculogyric crises, paresthesia, peripheral neuropathy, somnolence, syncope, taste alterations[Ref]


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

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


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


Frequency not reported: Abdominal pain and distress, burning sensation of the tongue, constipation, dark saliva, development of duodenal ulcer, diarrhea, dry mouth, dyspepsia, dysphagia, flatulence, gastrointestinal bleeding, gastrointestinal pain, heartburn, hiccups, nausea, sialorrhea, vomiting[Ref]


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


Frequency not reported: Abnormal lactic dehydrogenase, anorexia, edema, elevated serum glucose, elevated serum potassium, weight gain, weight loss[Ref]


Frequency not reported: Back pain, leg pain, muscle cramps, shoulder pain[Ref]


Frequency not reported: Bizarre breathing patterns, cough, dyspnea, pharyngeal pain, upper respiratory infection[Ref]


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


Frequency not reported: Blurred vision, dilated pupils, diplopia[Ref]


Frequency not reported: Dark urine, priapism, urinary frequency, urinary incontinence, urinary retention, urinary tract infection[Ref]


Frequency not reported: Asthenia, faintness, fatigue, hoarseness, malaise, 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, protein and glucose in the urine, white blood cells, bacteria and blood in the urine,[Ref]


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

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

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