Namenda (memantine) can cause side effects that range from mild to serious. More common side effects include dizziness and headache. If side effects from Namenda become difficult to tolerate, talk with your doctor.

Namenda is used in adults to treat dementia caused by Alzheimer’s disease.

Keep reading to learn about the common, mild, and serious side effects Namenda can cause.

Note: As a person’s condition progresses, they may need help reading or understanding certain information about their treatment plan. This article contains details that may help caregivers learn more about key aspects of Namenda.

Namenda can cause certain side effects, some more common than others. These side effects may be temporary, lasting a few days to weeks. Talk with your doctor if side effects do not go away, get worse, or become too difficult to tolerate.

More common side effects reported in people taking Namenda include:

For more information about confusion, see the “Side effects explained” section.

Mild side effects that have been reported with Namenda include:

For more information about confusion, see the “Side effects explained” section.

In most cases, these side effects should be temporary. And some may be managed easily. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop taking Namenda unless your doctor recommends it.

Namenda may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

Namenda may cause serious side effects. The following list may not include all possible serious side effects of the drug. For more information, you can refer to Namenda’s prescribing information.

If you develop serious side effects while taking Namenda, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

High blood pressure was reported as a serious side effect in studies of Namenda.

The following serious side effects were reported after Namenda became available for use:

For more information about mental health changes and SJS, see the “Side effects explained” section.

Note:After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect while taking Namenda and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Allergic reaction

For some people, Namenda can cause an allergic reaction. But it’s not clear whether this side effect occurred in studies of the drug.

In general, symptoms of allergic reaction can be mild or serious.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should keep taking Namenda.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 right away. Or call your local emergency number. These symptoms could be life threatening and require immediate medical care.

Your doctor can confirm whether you’ve had a serious allergic reaction to Namenda. If they do, they may have you switch to a different treatment.

Namenda is not expected to cause different side effects in older adults (ages 65 and older). In studies of Namenda, older adults experienced side effects similar to those in younger adults.

If you’re concerned about the safety of Namenda given your age, talk with your doctor.

Namenda can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Namenda is a good treatment option for you.

Talk with your doctor about your health history before starting Namenda treatment. They can discuss whether you should take Namenda. Be sure to tell them if any of the following factors apply to you:

Get answers to some frequently asked questions about Namenda’s side effects.

Can Namenda (memantine) make dementia worse?

No, Namenda does not worsen dementia as a side effect. Namenda is approved to treat dementia caused by Alzheimer’s disease. But it’s important to note that Namenda cannot cure Alzheimer’s disease. It can slow the progression (worsening) of the disease, but dementia can still worsen over time even during Namenda treatment.

Also, confusion is both a common side effect of Namenda and a symptom of dementia. So taking Namenda might make it seem like your dementia is worsening. To learn more about confusion and Namenda, see the “Side effects explained” section.

If your dementia seems to be getting worse or you’re experiencing severe confusion while taking Namenda, talk with your doctor.

Does Namenda cause long-term side effects?

It’s unlikely. Long-term side effects were not reported in studies of Namenda.

Long-term side effects refer to side effects that can start at any time during treatment or side effects that don’t go away even after you stop taking the drug.

If you’re concerned about possible long-term side effects from Namenda, talk with your doctor or pharmacist.

Learn more about some of the side effects Namenda may cause.

Confusion

Confusion was a common side effect reported in studies of Namenda. With confusion, you cannot think clearly. You may have a hard time focusing or making decisions. Confusion is also one of the symptoms of dementia. So if you already experience confusion due to dementia, Namenda may cause more of it.

Signs of confusion may include:

  • difficulty speaking
  • incoherent speech
  • slurring of words
  • forgetting what you’re doing while completing a task
  • being unaware of the location or time

Extreme confusion can lead to delirium, which is a sudden change in your mental state.

What might help

If you experience confusion during Namenda treatment, consider asking a loved one for help. You may need help doing things you’ve done on your own before. You should also talk with your doctor. They can help determine the cause of your confusion and recommend the appropriate treatment.

Mental health changes

Namenda can cause mental health changes. These include hallucinations (seeing or hearing things that aren’t there) and suicidal thoughts and behaviors. But it’s unclear how often suicidal thoughts and behaviors occurred and whether Namenda was the direct cause.

Signs of suicidal thoughts and behaviors may include:

What might help

If you experience any mental health changes while taking Namenda, talk with your doctor right away. Also let them know right away if you have suicidal thoughts or behaviors. They can help determine the cause and whether you should continue taking Namenda. If needed, they can also refer you to a mental health professional for treatment.

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

  • Call or text the 988 Suicide and Crisis Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you’re not in the same household, stay on the phone with them until help arrives.

Stevens-Johnson syndrome (SJS)

SJS has occurred in people taking Namenda. SJS is a rare but serious skin reaction that can cause your skin to loosen and detach from your body. This side effect did not occur in studies of the drug, but it was reported after the drug was approved for use. It’s unclear how often this occurred and whether Namenda was the direct cause.

Symptoms of SJS may include:

  • blistering rash that may or may not involve your mucous membranes
  • sore throat
  • cough
  • red eyes
  • muscle aches
  • peeling skin

What might help

SJS is a potentially life threatening condition that requires immediate medical care. Get medical help right away if you develop any symptoms of SJS and if any of the following apply to you:

  • you started a new medication in the last 8 weeks
  • you have a rash that resembles the skin reaction of SJS
  • you have a personal or family history of SJS or toxic epidermal necrolysis (TEN)

Your doctor will likely have you stop taking Namenda and provide treatment for your symptoms.

Keeping track of side effects

During your Namenda treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Namenda affects you. They can then use this information to adjust your treatment plan if needed.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.