Caregivers should watch for dizziness, headache, new or worsening confusion, and constipation in someone taking Namenda. Hallucinations and shortness of breath need prompt medical attention. Namenda was the brand name for memantine, a medicine used for moderate-to-severe Alzheimer's dementia. The brand product is no longer marketed, but generic memantine remains available, according to MedlinePlus.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Which side effects are most common?
- How can caregivers spot a meaningful change?
- Which symptoms require urgent attention?
- Who needs a closer medication review?
- What should caregivers do about missed doses?
Which side effects are most common?
In placebo-controlled dementia trials, the most common reactions were dizziness, headache, confusion, and constipation. The DailyMed prescribing information reports these rates: Other reactions that occurred more often with memantine included sleepiness, hallucinations, vomiting, high blood pressure, fatigue, pain, and shortness of breath.
These comparisons matter because symptoms in the memantine group were not automatically caused by the drug. People receiving placebo also experienced them, sometimes at similar rates.
- Dizziness: 7% with memantine versus 5% with placebo
- Headache: 6% versus 3%
- Confusion: 6% versus 5%
- Constipation: 5% versus 3%
How can caregivers spot a meaningful change?
Confusion, fatigue, sleepiness, and behavior changes can be difficult to interpret in someone with dementia. Focus on what changed after the medicine was started, restarted, or adjusted rather than on the symptom alone.
Keep a brief daily record that includes: Share specific observations with the prescriber. "She became too dizzy to walk safely two hours after each morning dose" is more useful than "She seems worse." Do not assume that worsening confusion is simply the dementia progressing. A clear timeline can help the clinician decide whether memantine, another medicine, or a separate health problem needs evaluation.
- When each dose was given
- New symptoms and when they began
- Falls, unsteadiness, or unusual sleepiness
- Bowel movements if constipation is a concern
- Hallucinations, aggression, depression, or abrupt behavior changes
Which symptoms require urgent attention?
Contact the prescribing clinician promptly about hallucinations or other severe or rapidly worsening symptoms. Seek emergency evaluation for shortness of breath, especially when breathing appears seriously impaired; MedlinePlus lists both hallucinations and shortness of breath among serious effects. Rare problems reported after memantine reached the market include acute kidney failure, hepatitis, pancreatitis, congestive heart failure, suicidal thoughts, severe blood-cell disorders, and Stevens-Johnson syndrome.
These voluntary reports cannot show how often the events occur or prove that memantine caused them. Do not wait for a routine appointment when a person has breathing difficulty, suicidal thoughts, or another rapidly developing severe reaction. Tell the treating team that the person takes memantine and provide the dose and time of the last dose.
Who needs a closer medication review?
Kidney function affects how the body clears memantine. Severe kidney impairment requires a lower target dose, so the prescriber needs an accurate medication list and relevant kidney information. Urine that becomes more alkaline can reduce memantine clearance by about 80%, increasing drug exposure.
The DailyMed label also advises caution when memantine is used with amantadine, ketamine, or dextromethorphan. Dextromethorphan appears in some cough medicines. Before adding an over-the-counter product, show its ingredient list to the pharmacist or prescriber rather than relying only on the brand name.
What should caregivers do about missed doses?
Do not give two doses to make up for one that was missed. Resume according to the prescriber's or pharmacist's instructions. If the person has missed memantine for several days, contact the prescriber before restarting it.
The dose may need to be restarted lower and increased gradually again. Trial results also have limits. The placebo-controlled studies lasted up to 28 weeks, and discontinuation because of adverse reactions was similar with memantine and placebo—10.1% versus 11.5%. Those figures may not reflect what an individual experiences during longer-term routine care.
