Memory Digest

Memantine

How memantine (Namenda) works for moderate to severe Alzheimer's, who it helps, side effects, and how it is used with other medicines.

Last reviewed: October 2026

Memantine (brand name Namenda, also available as generic and in combination with donepezil as Namzaric) is a long-used medicine for moderate to severe Alzheimer's Disease. It does not cure Alzheimer's or stop the underlying disease. For some people it modestly helps thinking, daily function and behavior for a period of time. It works differently from the Cholinesterase Inhibitors and Memantine (donepezil, rivastigmine, galantamine) and is often taken with one of them.

For the bigger picture of options, see Dementia Treatments: An Overview.

How it works

Nerve cells use a chemical messenger called glutamate for learning and memory. In Alzheimer's, excess glutamate activity can overstimulate NMDA receptors and contribute to cell damage. Memantine is an NMDA receptor antagonist: it partially blocks that overstimulation while still allowing normal signaling. That is a different mechanism from cholinesterase inhibitors, which raise acetylcholine levels.

Who it is for

In the United States, memantine is FDA-approved for moderate to severe Alzheimer's dementia—roughly the Middle-Stage Dementia and Late-Stage Dementia of disease. Evidence of clear benefit in mild Alzheimer's is weaker; reviews have not shown consistent meaningful benefit there.

Doctors sometimes use memantine in other dementias (for example mixed Alzheimer's and Vascular Dementia), but the strongest evidence is in Alzheimer's. It is not a substitute for treating Reversible Causes of Memory Problems or for non-drug approaches.

Memantine is not the same as anti-amyloid infusions such as Lecanemab (Leqembi) and Donanemab (Kisunla), which target amyloid in early disease. Those drugs are for Mild Cognitive Impairment (MCI) or mild dementia with confirmed amyloid, not typical moderate-to-severe symptomatic treatment.

What benefits to expect

A major Cochrane review found that memantine produces small benefits in cognition, activities of daily living, and clinician impression of change in people with moderate to severe Alzheimer's, with a small reduction in agitation in some analyses. Benefits are usually described as modest: some families notice better attention, less confusion or easier daily care; others notice little change. Often the aim is to slow worsening of function for a time rather than restore lost abilities.

It can take weeks to judge effect. Keep a simple diary of thinking, mood, sleep and daily tasks to share with the clinician.

Forms and dosing

Memantine comes as:

• Immediate-release tablets (often started low and increased weekly)
• Extended-release capsules (once daily)
• Oral solution in some markets
• Combination capsule with donepezil (Namzaric) for people already stable on both

Doses are reduced in kidney problems, because the drug is cleared by the kidneys. Never change the dose on your own. Take it at the same time each day; extended-release capsules are usually swallowed whole.

Side effects

Memantine is generally well tolerated compared with many brain medicines. Possible side effects include:

• Dizziness
• Headache
• Confusion (paradoxically, in some people)
• Constipation
• Sleepiness or, less often, sleep disturbance
• High blood pressure in some patients

Serious reactions are uncommon but need urgent care if severe allergic symptoms, seizures, or sudden major mental status change occur. Tell the doctor about all medicines and supplements—interactions matter, including with certain other NMDA-active drugs.

If side effects appear, the clinician may slow titration, lower the dose, or stop the drug. Do not stop abruptly without advice unless an emergency requires it.

Combining with cholinesterase inhibitors

Many people with moderate Alzheimer's take both a cholinesterase inhibitor and memantine. Studies support that combination for some patients. Side-effect profiles differ, so combining is often feasible. See Cholinesterase Inhibitors and Memantine.

Practical tips

• Use a pill organizer or caregiver-managed doses
• Align refill dates with other medicines to avoid gaps
• Ask whether cost differences between brand, generic and combination pills matter for your insurance
• Review the drug list at every visit—especially after hospital stays
• Reassess every few months: if the person is bedbound with minimal awareness and no clear benefit, deprescribing may be appropriate as goals shift to comfort in Late-Stage Dementia care

Memantine is not enough alone

Medicine is only one part of care. Non-Drug Treatments for Dementia, routines, Home Safety, Communicating with Someone with Dementia, exercise, social connection and caregiver support often matter as much or more day to day. See Caregiving Guide: Where to Start and Living Well with Dementia.

Bottom line

Memantine is an established, usually well-tolerated option for moderate to severe Alzheimer's that can offer small gains in thinking and daily function for some people. Discuss fit, kidney dosing, combination with cholinesterase inhibitors, and when to continue or stop with a clinician who knows the full care plan—not based on ads or online claims alone.

Sources

1. National Institute on Aging: How Is Alzheimer's Disease Treated?
2. McShane R et al. Memantine for dementia. Cochrane Database Syst Rev, 2019
3. Alzheimer's Association: Medications for Memory
4. Mayo Clinic: Memantine (oral route)

Not medical advice. This article is general information, not a diagnosis or treatment plan for any individual. Talk with a doctor about your situation.

Related articles

• Cholinesterase Inhibitors and Memantine
• Dementia Treatments: An Overview
• Alzheimer's Disease
• Middle-Stage Dementia
• Late-Stage Dementia