Donepezil is a medication primarily used to treat Alzheimer's disease, a progressive brain disorder that affects memory and cognitive function. It works by increasing levels of a neurotransmitter called acetylcholine, which is important for learning and memory. By enhancing communication between nerve cells, donepezil can help improve symptoms related to memory and thinking. This medication is typically prescribed for mild to moderate cases of Alzheimer's and is taken orally, usually once a day. While donepezil can help manage symptoms, it does not cure the disease or stop its progression. Common side effects may include nausea, diarrhea, and insomnia.