From the Guidelines
The main side effects of Sinemet (carbidopa/levodopa) include nausea, vomiting, abdominal pain, dyspepsia, constipation, weight decrease, dry mouth, diarrhea, anorexia, and GI disorders. These side effects are commonly reported by patients and can significantly impact their quality of life 1. According to the espen guideline clinical nutrition in neurology, the use of levodopa may be associated with impaired nutritional status and risk for malnutrition, particularly with increasing doses 1.
Some of the key side effects to consider include:
- Nausea and vomiting, which can lead to weight loss and malnutrition
- Abdominal pain and dyspepsia, which can affect food intake and digestion
- Constipation, which can be a significant issue for patients with Parkinson's disease
- Dry mouth and diarrhea, which can impact oral health and hydration
- Anorexia, which can lead to weight loss and malnutrition
It's essential to note that the mechanism of drug-related weight changes is still not well known and requires further investigation 1. However, research has indicated that weight loss among levodopa users, especially in women, may be due to higher levodopa dose per kg of body weight, and after starting levodopa treatment 1.
Long-term use of Sinemet can also lead to other side effects, such as:
- Metabolic effects, including changes in lipid and carbohydrate metabolism
- Hyperhomocysteinemia, which can increase the risk of cardiovascular diseases, dementia, and depression
- Dyskinesias and motor fluctuations, which can impact motor function and quality of life
Overall, it's crucial to carefully monitor patients taking Sinemet and adjust the dosage or treatment plan as needed to minimize side effects and optimize treatment outcomes 1.
From the FDA Drug Label
The most common adverse reactions reported with carbidopa and levodopa therapy have included dyskinesias, such as choreiform, dystonic, and other involuntary movements and nausea. The following other adverse reactions have been reported with carbidopa and levodopa: Body as a Whole: chest pain, asthenia Cardiovascular: cardiac irregularities, hypotension, orthostatic effects including orthostatic hypotension, hypertension, syncope, phlebitis, palpitation. Gastrointestinal: dark saliva, gastrointestinal bleeding, development of duodenal ulcer, anorexia, vomiting, diarrhea, constipation, dyspepsia, dry mouth, taste alterations Hematologic: agranulocytosis, hemolytic and nonhemolytic anemia, thrombocytopenia, leukopenia. Hypersensitivity: angioedema, urticaria, pruritus, Henoch-Schönlein purpura, bullous lesions (including pemphigus-like reactions). Musculoskeletal: back pain, shoulder pain, muscle cramps Nervous System/Psychiatric: psychotic episodes including delusions, hallucinations, and paranoid ideation, bradykinetic episodes (“on-off" phenomenon), confusion, agitation, dizziness, somnolence, dream abnormalities including nightmares, insomnia, paresthesia, headache, depression with or without development of suicidal tendencies, dementia, pathological gambling, increased libido including hypersexuality, impulse control symptoms. Convulsions also have occurred; however, a causal relationship with carbidopa and levodopa has not been established. Respiratory: dyspnea, upper respiratory infection. Skin: rash, increased sweating, alopecia, dark sweat. Urogenital: urinary tract infection, urinary frequency, dark urine Laboratory Tests: decreased hemoglobin and hematocrit; abnormalities in alkaline phosphatase, SGOT (AST), SGPT (ALT), LDH, bilirubin, BUN, Coombs test; elevated serum glucose; white blood cells, bacteria, and blood in the urine
The main side effects of Sinemet (carbidopa/levodopa) are:
- Dyskinesias (involuntary movements)
- Nausea
- Cardiovascular effects (e.g. hypotension, hypertension)
- Gastrointestinal effects (e.g. vomiting, diarrhea, constipation)
- Hematologic effects (e.g. anemia, thrombocytopenia)
- Hypersensitivity reactions (e.g. angioedema, urticaria)
- Musculoskeletal effects (e.g. back pain, muscle cramps)
- Nervous System/Psychiatric effects (e.g. psychotic episodes, confusion, depression) 2
From the Research
Main Side Effects of Sinemet (Carbidopa/Levodopa)
The main side effects of Sinemet (carbidopa/levodopa) include:
- Abnormal involuntary movements, such as dyskinesia and dystonia 3, 4, 5
- Hallucinations and psychosis 3, 4
- Nausea and vomiting, although these are less common with Sinemet than with levodopa alone 3
- Cardiac and respiratory arrhythmias, although these are also less common with Sinemet than with levodopa alone 3
- Sleep disruption 4
- "Wearing off" phenomena and fluctuations in motor performance 6, 7
- Response fluctuations, including "on" and "off" times 4, 6
Comparison of Sinemet and Sinemet CR
Studies have compared the side effects of standard Sinemet and controlled-release Sinemet CR, with results showing that Sinemet CR may have fewer side effects, including: