WEBMay 16, 2023 · Donepezil's most common side effects are gastrointestinal, i.e., diarrhea, nausea, and vomiting; dizziness, sleeplessness/fatigue, and urinary incontinence also have been reported. These are known class effects of cholinergic therapies, and often occur primarily at the beginning of treatment. One post-hoc analysis reported an inverse ...