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Lodosyn Side Effects

Generic name: carbidopa

Medically reviewed by Last updated on Nov 12, 2020.

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

For the Consumer

Applies to carbidopa: oral tablet

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of depression, thoughts of suicide, nervousness, emotional ups and downs, thinking that is not normal, anxiety, or lack of interest in life.
  • Signs of high or low blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
  • Change in the way you act.
  • Hallucinations (seeing or hearing things that are not there).
  • Feeling confused.
  • Strong urges that are hard to control (such as eating, gambling, sex, or spending money).
  • Throwing up blood or throw up that looks like coffee grounds.
  • Black, tarry, or bloody stools.
  • Belly pain.
  • A burning, numbness, or tingling feeling that is not normal.
  • Any unexplained bruising or bleeding.
  • Chest pain or pressure.
  • A heartbeat that does not feel normal.
  • Fever or chills.
  • Sore throat.
  • A skin lump or growth.
  • Change in color or size of a mole.
  • Change in eyesight, eye pain, or very bad eye irritation.
  • Trouble controlling body movements that is new or worse.
  • Grinding of teeth.
  • Shortness of breath.
  • Feeling very tired or weak.
  • Swelling in the arms or legs.
  • A very bad and sometimes deadly health problem called neuroleptic malignant syndrome (NMS) may happen. Call your doctor right away if you have any fever, muscle cramps or stiffness, dizziness, very bad headache, confusion, change in thinking, fast heartbeat, heartbeat that does not feel normal, or are sweating a lot.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Dizziness.
  • Headache.
  • Dry mouth.
  • Feeling sleepy.
  • Not able to sleep.
  • Upset stomach or throwing up.
  • Change in taste.
  • Constipation.
  • Diarrhea.
  • Not hungry.
  • Strange or odd dreams.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

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]


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


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.

Frequently asked questions

Further information

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

Some side effects may not be reported. You may report them to the FDA.