Namenda (memantine hydrochloride) is a brand-name drug that’s prescribed for Alzheimer’s disease in adults. It’s available as an oral tablet and extended-release capsule. As with other drugs, Namenda can cause side effects, including headache and dizziness.

Namenda can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist. These side effects can also vary depending on the drug form you’re taking.

More common side effects reported by people who took Namenda tablets in clinical trials include:

More common side effects reported by people who took Namenda extended-release (XR) capsules in clinical trials include:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Namenda use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to the prescribing information for Namenda tablets and Namenda XR capsules.

Mild side effects that have been reported with Namenda tablets and Namenda XR capsules include:

  • high blood pressure
  • dizziness
  • constipation
  • diarrhea
  • vomiting
  • cough
  • shortness of breath
  • fatigue
  • drowsiness
  • pain, including back pain
  • headache*
  • mild mental health changes, including confusion*

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Namenda and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Namenda may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to the prescribing information for Namenda tablets and Namenda XR capsules.

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.

Serious side effects that have been reported include mental health changes (see the “Side effect specifics” section for more details).

ALLERGIC REACTION

For some people, Namenda can cause an allergic reaction.

But it’s not clear whether this side effect occurred in studies of Namenda tablets and Namenda XR capsules.

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

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Namenda tablets or Namenda XR capsules, your doctor may recommend taking a different medication instead.

Namenda may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Can Namenda (memantine) worsen symptoms of dementia?

It’s possible. Dementia symptoms, including confusion, were reported with taking Namenda tablets. Mood changes, such as depression, were reported with taking Namenda XR capsules.

However, Alzheimer’s disease progression can also lead to worsening dementia. There is no cure for Alzheimer’s disease. Medications, such as Namenda, can only slow the progression of the disease. Thus, the symptoms of worsening dementia you may be experiencing can also be due to the progression of Alzheimer’s disease.

Talk with your doctor if you have a question about your disease progression.

Does Namenda cause long-term side effects?

It’s unlikely. Long-term side effects weren’t reported in studies of Namenda tablets and Namenda XR capsules.

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

Can Namenda side effects differ in the elderly or older adults?

It’s unlikely. Reported side effects were not meaningfully different between older and younger adults when taking Namenda tablets and Namenda XR capsules. (Older adults are people ages 65 years and older.)

Talk with your doctor or pharmacist if you have additional questions regarding the safety of Namenda given your age.

Learn more about some of the side effects that Namenda may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Namenda tablets and Namenda XR capsules.

Headache

Headache was a common side effect reported in clinical trials of Namenda tablets and Namenda XR capsules. Symptoms include:

  • dull pain around the band of the head
  • slow onset of head pain

What you can do

If you experience headache symptoms that are bothersome and not improving, talk with your doctor right away. Experiencing a headache with confusion could signal a serious health problem, such as a stroke.

Additionally, confusion is also a common side effect of Namenda. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Mental health changes

Mental health changes are a side effect reported with taking Namenda tablets and Namenda XR capsules. For example, depression and anxiety were reported with taking Namenda XR capsules. Hallucinations and confusion were reported with taking Namenda tablets.

Depression and anxiety may cause symptoms such as:

  • depressed mood
  • low energy and tiredness
  • appetite and body weight changes
  • nervousness or irritability
  • trouble sleeping

Hallucinations and confusion may cause symptoms such as:

  • sensory experiences that seem real but didn’t actually occur
  • inability to focus or concentrate
  • feelings of disconnection from time or place
  • not recognizing familiar faces

What you can do

Talk with your doctor if you are experiencing the above symptoms. They can adjust your Namenda dosage to help better manage your side effects. They may also recommend stopping Namenda and starting another medication for Alzheimer’s disease.

Below is important information you should consider before taking Namenda.

There were no contraindications or boxed warnings reported by the drug maker for Namenda tablets and Namenda XR capsules. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). Contraindications relate to health conditions or factors that raise your risk of harm. In such cases, your doctor may not prescribe Namenda for you.

Other precautions

Before taking Namenda, discuss your health history with your doctor. Namenda may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

  • bladder or kidney problems
  • liver problems
  • seizures
  • difficulty urinating
  • previous allergic reaction to this or a similar drug
  • pregnancy
  • breastfeeding
  • alcohol consumption

Disclaimer: Medical News Today 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.