The following table gives an overview of the most frequent (>4% for memantine) adverse events (irrespective of causal relationship) that were observed in the trial population of patients with moderate to severe dementia. (See table.)

Common adverse reactions (1-10% and more frequent than with placebo) for memantine and placebo patients respectively were: Hallucinations (2% vs 0.7%), confusion (1.3% vs 0.3%), dizziness (1.7% vs 1%), headache (1.7% vs 1.4%) and tiredness (1% vs 0.3%).
Uncommon adverse reactions (0.1-1% and more frequent than with placebo) were anxiety, hypertonia (increased muscle tone), vomiting, cystitis and increased libido.
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