My research today stems from my mother's (Parkinson's patient) 8 week bout of severe diarrhea. It started along with some occasional nausea and vomiting at about the same time she began taking Sinemet. I know these are two of the side effects of this drug but she has now been off the drug for nearly 5 weeks and is still experiencing severe diarrhea. She was hospitalized for 5 days, underwent tests including endoscopy, colonoscopy, barium ex-ray and bacteria all of which turned up no abnormalities. I am wondering if it is possible that she is still experiencing this as a side-effect of the medication. The drug companies are unable to tell me if this is a possibility or not. Anyone else experience adverse side effects that lasted this long?