The most serious adverse reactions associated with the administration of Larodopa having frequent occurrences are: adventitious movements such as choreiform and/or dystonic movements. Other serious adverse reactions with a lower incidence are: cardiac irregularities and/or palpitations, orthostatic hypotensive episodes, bradykinetic episodes (the "on-off" phenomena), mental changes including paranoid ideation and psychotic episodes, depression with or without the development of suicidal tendencies, dementia and urinary retention.
Rarely, gastrointestinal bleeding, development of duodenal ulcer, hypertension, phlebitis, hemolytic anemia, agranulocytosis and convulsions have been observed. (The causal relationship between convulsions and Larodopa has not been established.)
Adverse reactions of a less serious nature having a relatively frequent occurrence are the following: anorexia, nausea and vomiting with or without abdominal pain and distress, dry mouth, dysphagia, sialorrhea, ataxia, increased hand tremor, headache, dizziness, numbness, weakness and faintness, bruxism, confusion, insomnia, nightmares, hallucinations and delusions, agitation and anxiety, malaise, fatigue and euphoria. Occurring with a lesser order of frequency are the following: muscle twitching and blepharospasm (which may be taken as an early sign of overdosage; consideration of dosage reduction may be made at this time), trismus, burning sensation of the tongue, bitter taste, diarrhea, constipation, flatulence, flushing, skin rash, increased sweating, bizarre breathing patterns, urinary incontinence, diplopia, blurred vision, dilated pupils, hot flashes, weight gain or loss, dark sweat and/or urine.
Rarely, oculogyric crises, sense of stimulation, hiccups, development of edema, loss of hair, hoarseness, priapism and activation of latent Horner's syndrome have been observed.
Elevations of blood urea nitrogen, SGOT, SGPT, LDH, bilirubin, alkaline phosphatase or protein-bound iodine have been reported; and the significance of this is not known. Occasional reductions in WBC, hemoglobin and hematocrit have been noted.
Leukopenia has occurred and requires cessation, at least temporarily, of Larodopa administration. The Coombs' test has occasionally become positive during extended therapy. Elevations of uric acid have been noted when colorimetric method was used but not when uricase method was used.