Memantine Side Effects: What Families Should Watch For

Short answer: The most common memantine side effects are dizziness, headache, confusion, constipation and sleepiness. Less often, memantine causes agitation, hallucinations or higher blood pressure. Most effects are mild and appear when the medicine is started or the dose is raised. In older adults, dizziness and confusion matter most because they raise the risk of falls. Report any new change to the prescriber, and don’t stop or change memantine on your own.

What memantine does

Memantine (brand name Namenda) is prescribed for moderate to severe Alzheimer’s disease. It works differently from donepezil: it calms excess activity of glutamate, a chemical messenger in the brain. Because the two act in different ways, many people take them together, sometimes as a single combined capsule. Memantine is usually started low and increased step by step, which helps keep side effects down.

Common memantine side effects

Higher blood pressure is also listed among common effects, so blood pressure checks are worth keeping up, especially for people already treated for hypertension.

Memantine side effects in the elderly

Falls. Dizziness and sleepiness, on top of dementia, make falls more likely. Clear walkways, use night-lights and help with standing up for the first weeks after a dose change.

Agitation and hallucinations. Memantine is generally well tolerated, but a small number of people become more agitated, restless or anxious, usually soon after starting or after a dose increase. Hallucinations are less common. Note when the change began and tell the prescriber promptly; a sudden change can also be delirium from another cause.

Kidney function. Memantine leaves the body through the kidneys, so reduced kidney function can raise its level. Make sure the prescriber knows about any kidney problems.

Constipation. In an older adult who cannot describe discomfort, constipation can show up as restlessness or evening agitation. Our guide to sundowning covers other evening triggers.

Medicines and conditions to mention to the doctor

• Medicines with similar actions, such as amantadine and the cough suppressant dextromethorphan.
• Anything that makes urine more alkaline, such as sodium bicarbonate or some glaucoma medicines, which can raise memantine levels.
• Kidney disease, seizures or heart conditions.
• Other dementia medicines, such as donepezil. Taking them together is common; our guide to donepezil side effects in the elderly covers that medicine.

A two-week record for the appointment

After starting memantine or changing the dose, a few daily notes help the prescriber judge the balance: dose changes and dates; dizziness, near-falls and falls; sleep and daytime dozing; bowel movements; and any agitation, hallucinations or new confusion, with the time of day. Bring blood pressure readings if you take them.

If side effects feel heavy and the benefit is hard to see, ask the prescriber directly: what benefit to expect at this stage, whether the dose or timing could change, and how any change would be made safely.

A daily routine alongside medical care

Brain Vitality is a sealed fabric pouch of dry herbs, worn externally at the navel and held by a reusable belt, with nothing to swallow. It is not a replacement for memantine or any prescribed medicine. In Dr. Wang’s practice records, family caregivers described what they noticed in sleep and daytime alertness during pouch use; these are selected, uncontrolled observations, explained in the evidence overview. Share the ingredient list with the prescriber before starting.

Questions about memantine side effects

Do memantine side effects go away?

Mild effects such as dizziness or headache often settle within the first weeks or after a dose step. Effects that persist, or any serious effect, should be reviewed with the prescriber.

Can memantine make dementia behavior worse?

In a small number of people it causes agitation or confusion, usually early on. Tell the prescriber, who can review the dose. Pain, infection and poor sleep can cause similar changes, so they should be checked too.

Is it safe to take memantine with donepezil?

They are commonly prescribed together, and a combined capsule exists. The prescriber watches for added side effects from both.

Sources

MedlinePlus: Memantine · Memantine prescribing information (DrugCentral) · Agitation provoked by memantine in dementia (Journal of Neuropsychiatry)

General education; this article does not replace the prescriber’s advice or the medicine’s official labeling. Report side effects to the FDA at 1-800-FDA-1088.