Aricept?

My mom has been taking Aricept for years now.  She now has severe diarrhea.  I asked her doctor if it was possible that Aricept was the cause even if she's been taking it for years.  He said it is possible.  They are going to perform a colonoscopy since they've all but ruled out any type of infection based on her stool samples.  I was wondering if anyone had to stop taking Aricept because of it's negative side effects?