Memantine (Namenda)

FDA Approved 2003

Reviewed by the HeyPsych Medical Review Board

Board-certified psychiatrists and mental health professionals

Published January 23, 2026•Updated January 23, 2026•Reviewed January 23, 2026

Clinical summary for Memantine (Namenda): Memantine is for moderate-to-severe Alzheimer’s dementia. It doesn’t work overnight and it doesn’t “fix” memory, but some people look steadier over weeks—less decline, a little more function, sometimes fewer behavioral spikes. The tradeoff: dizziness and confusion are common early on, and a small group can get more agitated or even hallucinate (especially during titration or with Lewy body dementia). Don’t stop it abruptly unless there’s a serious reaction—step down slowly.

What It's Used For

Memantine is best known for moderate-to-severe Alzheimer’s dementia. In psychiatry land, the “why” is usually neuropsychiatric: cognition and function, plus the behavioral volatility that comes with dementia. Separately, memantine has real evidence as an off-label option for body-focused repetitive behaviors like hair-pulling and skin-picking.

Primary Indications

Moderate-to-severe Alzheimer’s dementia: Helps slow symptom progression and support function over timeBehavioral volatility in dementia: Not a sedative, but sometimes part of a plan when agitation/irritability are riding shotgun with cognitive declineTrichotillomania (hair-pulling): Off-label option with randomized trial evidenceSkin-picking (excoriation) disorder: Off-label option with randomized trial evidence

Off-Label Uses

Dementia with Lewy bodies / Parkinson disease dementia (variable results; higher neuropsychiatric sensitivity)Comorbid vascular dementia (case-by-case, usually adjunctive)

What People Feel

This med has two storylines: dementia care and compulsive behaviors. Either way, it’s not a “feel it in an hour” medication. People usually notice changes over weeks—and sometimes the first thing they notice is side effects.

Subtle Stabilization (Weeks, not days)

"It didn’t make everything better, but things felt less like they were sliding downhill every day."

How Fast It Works

Memantine isn’t a PRN medication and it’s not built for instant calm. Blood levels rise within hours, but the real-world changes (function, behavior, compulsive symptoms) are typically tracked over weeks.

Hours

The medication is absorbed and reaches peak levels (IR peaks ~3–7 hours; XR peaks ~9–12 hours)

Days

Side effects (dizziness, confusion) often show up early—especially during titration

Weeks

Clinical benefit is usually assessed over several weeks (dementia care) or over ~8 weeks in body-focused repetitive behavior trials

60–80 hours

Long half-life means changes (including side effects) can linger after dose changes

How Well It Works

Much/Very Much Improved at 8 Weeks (Trichotillomania / Skin-Picking Disorder)

60.5%

vs 8.3%

For hair-pulling and skin-picking, memantine has surprisingly strong signal in an 8-week randomized, double-blind trial: about 6 in 10 people on memantine were rated “much” or “very much” improved, compared with under 1 in 10 on placebo. That’s the kind of difference patients actually feel.

Critical Safety Information

If confusion, agitation, or hallucinations spike—especially during dose increases—take it seriously. Sometimes the fix is simply slowing down or stepping back the dose.

→Titrate slowly. Most problems happen during dose increases, not at a stable dose.
→Report new or worsening hallucinations, delusions, agitation, or sudden confusion—especially if the person has Lewy body dementia.
→If dizziness or falls increase, pause and reassess the dose. Safety > speed.
→Tell your clinician if kidney function is reduced—dosing often needs adjustment.
→Avoid major alkalinizing changes without medical guidance (certain meds, supplements, and dietary shifts can raise urine pH and raise memantine levels).
→Don’t stop abruptly unless there’s a severe reaction—step down gradually to avoid rebound symptoms.

Side Effects

Most common: dizziness, headache, and confusion. It can also push sleep in the wrong direction and, in a smaller group, worsen agitation or hallucinations—particularly during titration or in neuropsychiatrically sensitive dementias.

Common Things People Notice

Dizziness (common)
Headache (common)
Confusion or increased disorientation (common, often titration-related)
Drowsiness or fatigue (can happen, but this is not primarily a sedative)
Constipation or diarrhea
Sleep disturbance
Agitation, delusions, hallucinations (less common but clinically important)

Common Side Effects

5% to 7%

Dizziness— This is a big one—especially early. Falls risk matters in dementia. If dizziness is intense, slow the titration or hold the dose longer before increasing.

Headache— Often shows up early and may fade with time. If headaches are persistent or severe, reassess dosing and hydration, and rule out other causes.

Immediate-release: 6%

Confusion— Paradoxical but real: some people get more confused during titration. Dose increases can be a trigger. If confusion spikes, pause the titration or step back.

Drowsiness— Memantine isn’t designed as a sedative, but sleepiness can happen. If daytime sleepiness increases, consider morning dosing (and make sure nothing else sedating was added).

Immediate-release: 3%

Hallucinations— More likely in people with Lewy body dementia or baseline hallucinations. If hallucinations worsen after an increase, treat it like a medication signal—not a behavior problem.

Extended-release: 4%

Anxiety / Irritability— Some people feel more keyed up during titration. If anxiety or agitation ramps up, slow down or reassess whether memantine is a net win.

⚠️ Serious Side Effects

Severe neuropsychiatric worsening: agitation, delusions, hallucinations, delirium—especially in susceptible dementias or during titration
Seizures (reported): higher caution in people with seizure history
Syncope, bradycardia, heart failure, prolonged QT (postmarketing reports): evaluate if fainting, palpitations, or new cardiac symptoms appear
Severe hypersensitivity reactions (rare): including Stevens-Johnson syndrome—urgent evaluation for rash or mucosal symptoms
Acute kidney injury (postmarketing reports): assess if sudden decline, dehydration, or medication interactions are present
Suicidal ideation (reported): monitor mood and safety, especially if neuropsychiatric symptoms shift

Critical Drug Interactions

Memantine doesn’t run through CYP the way many psych meds do, but it has two interaction “lanes” that matter: (1) stacking NMDA-like agents and (2) anything that alkalinizes urine and slows memantine clearance.

With: NMDA antagonist stacking (amantadine, ketamine; caution also with high-dose dextromethorphan)

Risk: Additive NMDA-related effects can increase confusion, dizziness, and psychotomimetic symptoms (agitation, hallucinations).

Action: Avoid unnecessary stacking. If overlap is unavoidable, go slower with titration and monitor neuropsychiatric status closely.

With: Urine alkalinizing agents or conditions (eg, sodium bicarbonate, major dietary shifts toward alkalinization)

Risk: Alkaline urine significantly reduces memantine clearance, increasing blood levels and side effects (confusion, dizziness, agitation).

Action: Use caution. If alkalinization is needed medically, consider dose adjustment and tighter monitoring.

With: Other CNS-active medications (sedatives, anticholinergics, polypharmacy in dementia)

Risk: Not a classic “dangerous combo,” but additive cognitive burden can look like memantine intolerance (confusion, falls, sleep disruption).

Action: If side effects show up, review the whole med list—memantine is often blamed when polypharmacy is the real driver.

Safe Discontinuation

Stopping memantine abruptly can backfire—some people worsen cognitively or behaviorally, and a subset can develop withdrawal-like symptoms (confusion, hallucinations, delusions, insomnia, increased anxiety and agitation). Unless there’s a severe adverse reaction, step it down gradually.

Key Points

Avoid abrupt discontinuation except for severe adverse reactions (eg, serious rash, severe neuropsychiatric decompensation clearly tied to the medication).
If stopping, use a gradual taper: either cut the dose ~50% and hold for about 4 weeks between reductions, or step down using available dose strengths.
An alternative taper is weekly decrements down to the lowest dose: decrease by 5 mg/day (immediate release) or 7 mg/day (extended release) at weekly intervals until the lowest dose, then discontinue.
If the condition clearly worsens after withdrawal, consider re-initiation—especially if the decline tracks closely with discontinuation.

Dosing Information

Adult Dosing

alzheimer ir initial: 5 mg PO once daily

alzheimer ir titration: Increase total daily dose by 5 mg each week as tolerated to 20 mg/day; may give once daily or in 2 divided doses when >5 mg/day

alzheimer ir max: 20 mg/day (10 mg PO BID or 20 mg once daily per clinician preference/tolerability)

alzheimer xr initial: 7 mg PO once daily

alzheimer xr titration: Increase by 7 mg weekly as tolerated to 28 mg once daily

alzheimer xr max: 28 mg PO once daily

trichotillomania skin picking initial: 10 mg PO once daily

trichotillomania skin picking titration: Increase to 20 mg PO once daily after 2 weeks if tolerated

trichotillomania skin picking target: 20 mg PO once daily

renal impairment ir: CrCl ≥50 mL/min: no adjustment. CrCl 30 to <50: start 5 mg once daily; titrate by 5 mg no more often than weekly; some patients may need a reduced max due to higher exposure. CrCl <30: start 5 mg once daily; after ≥1 week if tolerated, target 5 mg BID.

renal impairment xr: CrCl ≥50 mL/min: no adjustment. CrCl 30 to <50: start 7 mg once daily; titrate by 7 mg no more often than weekly; some patients may need a reduced max due to higher exposure. CrCl <30: start 7 mg once daily; after ≥1 week if tolerated, target 14 mg once daily.

dialysis: Not likely significantly dialyzable. Hemodialysis/peritoneal dialysis/CRRT: immediate-release dose as if CrCl <30 mL/min; extended-release: avoid use.

hepatic impairment: Mild-to-moderate: no adjustment. Severe: limited data; use with caution (Canada: not recommended).

geriatrics: Use adult dosing, but go slower if confusion, falls, or neuropsychiatric symptoms flare during titration.

conversion ir to xr: Start ER the day after the last IR dose. If current IR is 10 mg/day, convert to ER 14 mg once daily. If current IR is 20 mg/day, convert to ER 28 mg once daily.

missed doses: If several days are missed, restart at a lower dose and retitrate rather than jumping back to the previous dose.

administration: May take with or without food. ER capsules may be swallowed whole or opened and sprinkled on applesauce and swallowed immediately (do not chew/crush/divide). Oral solution should be measured with the provided device and slowly squirted into the corner of the mouth; do not mix with other liquids.

Simple Explanation

This is a slow-and-steady titration medication. The goal is to reach a therapeutic dose without triggering a confusion/agitation spiral. If side effects show up, the fix is usually not “push through”—it’s “slow down.”

Pregnancy, Breastfeeding, Special Groups

Memantine isn’t a go-to medication in pregnancy or breastfeeding because human data are limited. In older adults with dementia (the most common use case), dosing is the same as adults—but tolerability rules everything. Kidney function changes the dose.

👶Pregnancy

Human data are limited; adverse events have been observed in animal reproduction studies. Use during pregnancy only if the potential benefit justifies the potential risk.

🤱Breastfeeding

It is not known whether memantine is present in human breast milk. The manufacturer advises weighing infant exposure risk, breastfeeding benefits, and the mother’s treatment benefit. If used, monitor the infant for unusual sleepiness, feeding problems, or irritability.

👧Children & Adolescents (Under 18)

Not applicable for this medication.

👴Older Adults (65+)

Refer to adult dosing, but monitor more aggressively for dizziness, falls, confusion, sleep disturbance, and neuropsychiatric changes—especially during titration.

🔬Liver Impairment

Mild-to-moderate impairment: no adjustment. Severe impairment: limited data; use with caution (Canada: not recommended).

💧Kidney Impairment

Dose adjustments are commonly needed in renal impairment; exposure rises substantially as kidney function declines. Extended-release is generally avoided in dialysis and CRRT-type settings.

Clinical Monitoring

Cognitive function over time (trend matters more than a single score)
Functional outcomes: Activities of Daily Living (ADLs) and Instrumental ADLs (IADLs)
Neuropsychiatric symptoms: agitation, irritability, sleep disturbance, delusions, hallucinations—especially during titration or in Lewy body dementia
Falls and gait stability (dizziness/ataxia = safety risk)
Renal function for dosing decisions (use Cockcroft-Gault for adjustment in many clinical settings)
Blood pressure and cardiovascular symptoms in patients with cardiac disease (hypertension/hypotension, syncope risk)
Ophthalmic monitoring when clinically indicated (Canada recommends periodic ophthalmic exam; consider if corneal symptoms or eye disease are present)

Available Formulations

Immediate-Release Tablets (memantine HCl): 5 mg, 10 mg
Oral Solution (memantine HCl): 2 mg/mL; also labeled as 10 mg/5 mL presentations exist depending on product
Extended-Release Capsules (memantine HCl ER): 7 mg, 14 mg, 21 mg, 28 mg
Titration packs may exist historically; availability varies by market and manufacturer

Mechanism of Action

Memantine blocks NMDA-type glutamate receptors in a way that matters most when the system is overactivated. The concept is excitotoxicity: too much glutamate signaling can keep NMDA channels “open” too long, driving excess calcium influx and neuronal stress. Memantine sits in the channel (at the magnesium site) with a longer dwell time than magnesium, acting like a gate that closes down excessive stimulation while preserving more normal signaling. Mechanistically, it also binds with low affinity to the PCP site at the NMDA receptor—one reason a small subset of patients can experience agitation, delusions, or hallucinations, especially if the brain is already prone to dopamine/glutamate imbalance.

Place in Treatment Algorithm

Memantine is a standard option once Alzheimer’s dementia is moderate to severe. It’s often used alone or paired with a cholinesterase inhibitor when the goal is function and stability, not “symptom elimination.” From a psychiatry perspective, the key is behavior: dementia symptoms often come with agitation, sleep disruption, paranoia, or hallucinations, and memantine can be either a stabilizer or a trigger depending on the person. Separately, for trichotillomania and skin-picking disorder, memantine is an evidence-based off-label option that targets glutamate rather than serotonin—often considered when first-line behavioral approaches and/or SSRIs haven’t been enough.

Frequently Asked Questions

What is memantine used for in psychiatry?

Most commonly: moderate-to-severe Alzheimer’s dementia (which is absolutely part of psychiatry because cognition and behavior live together). Off-label, memantine also has solid evidence for trichotillomania (hair-pulling) and skin-picking (excoriation) disorder.

Will memantine calm agitation or help sleep?

Sometimes it helps indirectly if the overall dementia picture stabilizes, but memantine is not a sedative and it’s not a PRN “calm down” medication. In some people—especially during titration—it can actually worsen agitation or disrupt sleep. If agitation spikes right after a dose increase, slow down.

How long does memantine take to work?

Blood levels change within hours, but symptom changes are usually judged over weeks. For hair-pulling/skin-picking, the key study tracked outcomes over 8 weeks. For dementia care, clinicians usually look at trends over several weeks to months.

What are the most common side effects?

Dizziness, headache, and confusion are the big three. Constipation or diarrhea can happen too. Neuropsychiatric effects like agitation or hallucinations are less common, but they’re the ones you don’t ignore.

Can memantine cause hallucinations or make confusion worse?

Yes. Hallucinations and worsening confusion are reported, and risk can be higher in Lewy body dementia or in people who already hallucinate. It also tends to show up during titration—so if symptoms worsen after a dose increase, consider holding or stepping back rather than pushing forward.

What dose is used for trichotillomania or skin-picking?

A common approach is 10 mg once daily, then increase to 20 mg once daily after 2 weeks if tolerated. That matches the typical dosing used in clinical research for these conditions.

Do you have to adjust the dose for kidney disease?

Often, yes. Memantine exposure rises as kidney function declines. For more severe renal impairment, targets are lower (for example, IR may target 5 mg twice daily; XR may target 14 mg once daily). Dialysis/CRRT settings generally avoid the XR formulation.

Can you stop memantine abruptly?

Try not to—unless there’s a severe adverse reaction. Stopping suddenly can lead to worsening cognition or rebound neuropsychiatric symptoms (confusion, hallucinations, insomnia, anxiety/agitation). A gradual step-down is usually safer.

Does memantine interact with antidepressants?

It doesn’t have major CYP-based interactions like many psych meds, but the real-world issue is additive cognitive burden from polypharmacy. If confusion or falls increase, review the full medication list—not just memantine.

What should I watch for during titration?

A sudden jump in confusion, agitation, sleep disruption, dizziness, or hallucinations—especially right after a dose increase. If that happens, slow down, hold the dose longer, or step back. The goal is stability, not speed.

Is memantine a cure for Alzheimer’s?

No. It doesn’t reverse dementia. The realistic goal is slowing decline and supporting function and behavior for some people—often as part of a bigger plan that includes safety, routines, caregiver support, and (sometimes) other medications.

This medication information is for educational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider before starting, stopping, or changing any medication. Never take medication without a prescription from a licensed healthcare provider.

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Memantine (Namenda)

FDA Approved 2003

Reviewed by the HeyPsych Medical Review Board

Board-certified psychiatrists and mental health professionals

Published January 23, 2026•Updated January 23, 2026•Reviewed January 23, 2026