Donepezil, sold as the trade name Aricept among others, is a medication used to treat Alzheimer's disease. It appears to result in a small benefit in mental function and ability to function. Use, however, has not been shown to change the progression of the disease. Treatment should be stopped if no benefit is seen. It is taken by mouth.Common side effects include nausea, trouble sleeping, aggression, diarrhea, feeling tired, and muscle cramps. Serious side effects may include abnormal heart rhythms, frequent urge to urinate, and seizures. Donepezil is a centrally acting reversible acetylcholinesterase inhibitor and structurally unrelated to other anticholinesterase agents.Donepezil was approved for medical use in the United States in 1996. It is available as a generic medication. In the United Kingdom a typical month's supply costs the NHS about £0.52 as of 2019. The wholesale cost of this amount in the United States is about US$1.38. In 2017, it was the 127th most commonly prescribed medication in the United States, with more than five million prescriptions.