My husband started taking donepezil a few months ago without any problems. Someone from the memory clinic came to do an initial review and said they would be back in a year to review the medication with us. She said that even if someone had no side effects initially, they can develop side effects down the line. I haven't read anything to this effect so not sure but perhaps it is just some sort of stomach upset. Perhaps if it doesn't improve, talk to doctor.can anyone tell me if donepezil can cause diarrhea and vomiting after taking it for 2 years..