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memantine Side Effects

Also known as: Namenda

Analysis of 12,807 adverse event reports submitted to the FDA from 2004 to 2025.

Total Reports

12,807

Death-Related

1,934

15.1% of reports

Hospitalizations

5,255

41.0% of reports

Top Indication

Product Used For Unknown Indication

Most Reported Adverse Reactions

FALL
937
DEATH
853
DRUG INEFFECTIVE
811
OFF LABEL USE
740
CONFUSIONAL STATE
706
FATIGUE
605
HALLUCINATION
581
CONDITION AGGRAVATED
502
ASTHENIA
469
SOMNOLENCE
438
DIZZINESS
436
URINARY TRACT INFECTION
420
NAUSEA
404
DIARRHOEA
379
GAIT DISTURBANCE
346
AGITATION
344
PRODUCT DOSE OMISSION ISSUE
337
PNEUMONIA
321
HEADACHE
317
VOMITING
317

Who Reports Side Effects

Gender Distribution

Female 5,975 (52%)
Male 5,528 (48%)
Unknown 8

Age Distribution

0-17 181 (2%)
18-44 468 (5%)
45-64 1,144 (12%)
65-74 1,818 (20%)
75+ 5,631 (61%)

Reporting Trend by Year

2004 2025

Reactions in Death Reports

Top reactions reported in 1,934 reports where death was an outcome. These are voluntarily reported and do not establish causation.

Reaction Reports
DEATH 849
PNEUMONIA 118
FALL 107
OFF LABEL USE 80
HALLUCINATION 79
PARKINSON^S DISEASE 77
CONDITION AGGRAVATED 74
CONFUSIONAL STATE 72
TOXICITY TO VARIOUS AGENTS 68
ASTHENIA 67
DEMENTIA 67
DRUG INEFFECTIVE 66
URINARY TRACT INFECTION 64
DYSPHAGIA 63
SEPSIS 63
COMPLETED SUICIDE 54
PNEUMONIA ASPIRATION 50
FATIGUE 49
DYSPNOEA 48
GENERAL PHYSICAL HEALTH DETERIORATION 46

Reactions in Hospitalization Reports

Top reactions in 5,255 reports where hospitalization was an outcome.

Reaction Reports
FALL 607
CONFUSIONAL STATE 330
URINARY TRACT INFECTION 299
PNEUMONIA 255
ASTHENIA 246
FATIGUE 243
OFF LABEL USE 234
DRUG INEFFECTIVE 225
NAUSEA 188
DRUG INTERACTION 187
SOMNOLENCE 180
DEHYDRATION 176
VOMITING 176
DELIRIUM 159
CONDITION AGGRAVATED 157
HYPOTENSION 157
AGITATION 156
DIARRHOEA 156
DYSPNOEA 154
BRADYCARDIA 153

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What the FAERS Data Reveals About memantine Side Effects

The FDA Adverse Event Reporting System (FAERS) contains 12,807 voluntary reports linked to memantine and its brand equivalents (Namenda), spanning 2004 through 2025. Of those, 1,934 (15.1%) listed death as an outcome and 5,255 (41.0%) involved hospitalization. The most common indication reported alongside adverse events was Product Used For Unknown Indication.

Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 52% were female and 48% male; age distribution skews toward 75+, with 5,631 reports in that bracket. The single most reported reaction is fall with 937 submissions, followed by death and drug ineffective.

FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice — speak with a licensed clinician about any side-effect concerns.