Donepezil improves the function of nerve cells in the brain. It works by preventing the breakdown of a chemical called acetylcholine (ah see til KO leen). People with dementia usually have lower levels of this chemical, which is important for the processes of memory, thinking, and reasoning.

Donepezil is used to treat mild to moderate dementia caused by Alzheimer's disease.

Donepezil may also be used for other purposes not listed in this medication guide.

Before taking donepezil, tell your doctor if you have a heart rhythm disorder such as "sick sinus syndrome" (slow heartbeats), an enlarged prostate, urination problems, asthma, obstructive pulmonary disease, or a seizure disorder such as epilepsy.

If you need to have any type of surgery, tell the surgeon ahead of time that you are taking donepezil.

Donepezil can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

Do not take this medication if you are allergic to donepezil.

Before taking donepezil, tell your doctor if you are allergic to any drugs, or if you have:

• a heart rhythm disorder such as "sick sinus syndrome" (slow heartbeats);

• a history of stomach ulcers;

• an enlarged prostate or urination problems;

• epilepsy or other seizure disorder; or

• asthma or chronic obstructive pulmonary disease (COPD).

If you have any of these conditions, you may need a dose adjustment or special tests to safely take donepezil.

FDA pregnancy category C. This medication may be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

It is not known whether donepezil passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.