Side effect of sinemet tablet ( levodopa and carbidopa )

Patient: Dear SirMy father is suffered by Parkinson disease about 15 years ago.At the moment, he has to take sinemet tablet ( 275 mg ) about 10 tablets a day.I am afraid of this sinemet side effect. We try to let him have to reduce the Tablet but he can’t bear without taking this medicine. So, please give advise upon this condition and what is the side effects of taking too much of this medicine??