Several prescription drugs are currently approved by the U.S. Food and Drug Administration (FDA) to treat people who have been diagnosed with Alzheimer’s disease. Treating the symptoms of Alzheimer’s  can provide patients with comfort, dignity, and independence for a longer period of time and can encourage and assist their caregivers  as well.
It is important to understand that none of these medications stops the disease itself.
For information about managing medicines for people with Alzheimer's disease, read the tip sheet Managing Medicines  (PDF, 625K).
Volunteers—people with Alzheimer's or mild cognitive impairment  and healthy individuals—are needed to participate in Alzheimer's clinical research. Learn about participating in clinical trials .
Medications called cholinesterase inhibitors are prescribed for mild to moderate Alzheimer’s disease . These drugs may help delay or prevent symptoms from becoming worse for a limited time and may help control some behavioral symptoms . The medications include: Razadyne® (galantamine), Exelon® (rivastigmine), and Aricept® (donepezil). Another drug, Cognex® (tacrine), was the first approved cholinesterase inhibitor but is no longer available due to safety concerns.
Scientists do not yet fully understand how cholinesterase inhibitors work to treat Alzheimer’s disease , but research indicates that they prevent the breakdown of acetylcholine, a brain chemical believed to be important for memory and thinking. As Alzheimer’s progresses, the brain produces less and less acetylcholine; therefore, cholinesterase inhibitors may eventually lose their effect.
No published study directly compares these drugs. Because they work in a similar way, switching from one of these drugs to another probably will not produce significantly different results. However, an Alzheimer’s patient may respond better to one drug than another.
A medication known as Namenda® (memantine), an N-methyl D-aspartate (NMDA) antagonist, is prescribed to treat moderate to severe Alzheimer’s disease. This drug’s main effect is to delay progression of some of the symptoms of moderate to severe Alzheimer’s. It may allow patients to maintain certain daily functions a little longer than they would without the medication. For example, Namenda® may help a patient in the later stages  of the disease maintain his or her ability to use the bathroom independently for several more months, a benefit for both patients and caregivers.
Namenda® is believed to work by regulating glutamate, an important brain chemical. When produced in excessive amounts, glutamate may lead to brain cell death. Because NMDA antagonists work very differently from cholinesterase inhibitors, the two types of drugs can be prescribed in combination.
The FDA has also approved Aricept® for the treatment of moderate to severe Alzheimer’s disease.
Doctors usually start patients at low drug doses and gradually increase the dosage based on how well a patient tolerates the drug. There is some evidence that certain patients may benefit from higher doses of the cholinesterase inhibitors. However, the higher the dose, the more likely are side effects. The recommended effective dosages of drugs prescribed to treat the symptoms of Alzheimer’s and the drugs’ possible side effects are summarized in the table below.
Patients should be monitored when a drug is started. Report any unusual symptoms to the prescribing doctor right away. It is important to follow the doctor’s instructions when taking any medication, including vitamins and herbal supplements . Also, let the doctor know before adding or changing any medications.
Clinical trials are the best way to find out if promising new treatments are safe and effective in humans. Volunteer participants are needed for many Alzheimer’s trials conducted around the United States. To learn more, talk with your doctor or visit the ADEAR Center’s listing of clinical trials . More information is available at www.ClinicalTrials.gov .
To learn about support groups, research centers, research studies, and publications about Alzheimer’s disease, contact the following resources:
Alzheimer’s Disease Education and Referral (ADEAR) Center
P.O. Box 8250
Silver Spring, MD 20907-8250
The National Institute on Aging's ADEAR Center offers information and publications  for families, caregivers, and professionals on diagnosis, treatment, patient care, caregiver needs, long-term care, education, training, and research related to Alzheimer's disease. Staff members answer telephone, email, and written requests and make referrals to local and national resources. Visit the ADEAR website to learn more about Alzheimer's and other dementias, find clinical trials, and sign up for email updates .
225 North Michigan Avenue, Floor 17
Chicago, IL 60601-7633
The Alzheimer’s Association is a national nonprofit association with a network of local chapters that provide education and support for people diagnosed with Alzheimer’s, their families, and caregivers. The Association also supports research on Alzheimer’s.
Alzheimer's Foundation of America
322 Eighth Avenue, 7th Floor
New York, NY 10001
The Alzheimer's Foundation is a national nonprofit organization that serves people with Alzheimer's and their caregivers and families. Services include a toll-free hotline, publications, and online resources.
Note: This brief summary does not include all information important for patient use and should not be used as a substitute for professional medical advice. Consult the prescribing doctor and read the package insert before using these or any other medications or supplements. Drugs are listed in order of FDA  approval, starting with the most recent.
(To view this as one table, please open the PDF version of this publication.)
DRUG TYPE AND USE
HOW IT WORKS
COMMON SIDE EFFECTS
|Namenda® (memantine)||N-methyl D-aspartate (NMDA) antagonist prescribed to treat symptoms of moderate to severe Alzheimer’s||Blocks the toxic effects associated with excess glutamate and regulates glutamate activation||Dizziness, headache, constipation, confusion|
|Razadyne® (galantamine)||Cholinesterase inhibitor prescribed to treat symptoms of mild to moderate Alzheimer’s||Prevents the breakdown of acetylcholine and stimulates nicotinic receptors to release more acetylcholine in the brain||Nausea, vomiting, diarrhea, weight loss, loss of appetite|
|Exelon® (rivastigmine)||Cholinesterase inhibitor prescribed to treat symptoms of mild to moderate Alzheimer’s (patch is also for severe Alzheimer's)||Prevents the breakdown of acetylcholine and butyrylcholine (a brain chemical similar to acetylcholine) in the brain||Nausea, vomiting, diarrhea, weight loss, loss of appetite, muscle weakness|
|Aricept® (donepezil)||Cholinesterase inhibitor prescribed to treat symptoms of mild to moderate, and moderate to severe Alzheimer’s||Prevents the breakdown of acetylcholine in the brain||Nausea, vomiting, diarrhea|
MANUFACTURER’S RECOMMENDED DOSAGE
FOR MORE INFORMATION
||For current information about this drug’s safety and use, visit www.namenda.com . See Full Prescribing Information  (PDF, 555K).|
||For current information about this drug’s safety and use, visit www.razadyneer.com . See Full Prescribing Information  (PDF, 677K).|
||For current information about this drug’s safety and use, visit the www.fda.gov/Drugs . Click on "Drugs @ FDA," search for Exelon, and click on drug-name links to see "Label Information."|
||For current information about this drug’s safety and use, visit www.fda.gov/Drugs . Click on “Drugs @ FDA,” search for Aricept, and click on drug-name links to see “Label Information.”|
*Available as a generic drug.
Alzheimer's Disease Education and Referral (ADEAR) Center
A Service of the National Institute on Aging
National Institutes of Health
U.S. Department of Health and Human Services
November 2008 (Updated January 2014)