Memantine
A dementia medicine that dampens overactive glutamate signalling in the brain. Also used off label, with mixed evidence, for OCD, ADHD and some pain.
Quick answer: Memantine is a tablet approved for moderate to severe Alzheimer’s disease, where it slightly slows the loss of thinking and daily skills. Doctors sometimes use it off label, most often as an add-on for OCD, where the evidence is best. It’s usually well tolerated: dizziness, headache, constipation and sleepiness are the most common side effects.
At a glance
- For
- Moderate to severe Alzheimer’s disease (approved). Off label: OCD add-on, sometimes ADHD, autism and pain
- Works
- Small benefits in Alzheimer’s. In OCD, add-on trials show a modest extra drop in symptoms
- Cost
- $25 a script on the PBS for Alzheimer’s with an authority ($7.70 concession); private for other uses, and price varies
- Kicks in
- Weeks; judge it after 2–3 months at full dose
- Dose
- Starts at 5 mg and goes up weekly to 20 mg once a day; lower in kidney disease
- Watch for
- Dizziness, headache, constipation, sleepiness, raised blood pressure
Gentle, slow and modest. Not a cognitive enhancer for healthy brains, whatever the internet says.
Brand names
- Ebixa, and generic memantine brands
How it works
Memantine partly blocks NMDA receptors, which respond to glutamate, the brain’s main “go” signal. Too much glutamate activity is thought to harm nerve cells and drive repetitive, “stuck” loops of thought. Memantine turns down the background noise without blocking normal signalling.
Used for
- Moderate to severe Alzheimer’s disease (TGA-approved), alone or with a donepezil-type medicine
- Off label, OCD: added to an SSRI when symptoms persist. Several small randomised trials and meta-analyses show a moderate extra benefit
- Off label, ADHD: small trials, mostly as an add-on in adults. Evidence is weak
- Off label, autism: early small studies looked promising; a large company trial for social symptoms didn’t show benefit
- Off label, pain and migraine prevention: small studies, mixed results
Side effects
Most people get few side effects. Dizziness, headache, constipation and sleepiness are the most common, and usually settle. It can raise blood pressure a little.
Full side-effect list (from the product information)
How often, from the official product information. Bold = serious.
Common 1 in 10 to 1 in 100
- Dizziness
- Headache
- Sleepiness
- Constipation
- Raised blood pressure
- Shortness of breath
- Abnormal liver tests
- Allergic reactions (drug hypersensitivity)
Uncommon 1 in 100 to 1 in 1,000
- Confusion or hallucinations
- Vomiting
- Tiredness
- Unsteady walking
- Fungal infections
- Blood clots
- Heart failure
Very rare fewer than 1 in 10,000
- Seizures
- Pancreatitis
- Psychotic reactions
Get help urgently if
- New confusion, hallucinations or agitation
- A seizure
- Severe stomach pain with vomiting
- Chest pain, breathlessness or leg swelling. Call 000 if severe
Good to know
- Lower dose in moderate to severe kidney disease.
- Avoid combining with amantadine, ketamine or dextromethorphan (similar action).
- Things that make urine more alkaline (e.g. a strict vegetarian diet, large doses of antacids) can raise memantine levels.
- No withdrawal problems for most people, but stop through your doctor.
Common questions
What is memantine used for?
It’s approved for moderate to severe Alzheimer’s disease. Off label it’s sometimes added to an SSRI for OCD, and occasionally tried for ADHD, autism or pain, where the evidence is weaker.
Does memantine help OCD?
As an add-on to an SSRI, small randomised trials and meta-analyses show a moderate extra improvement. It’s an off-label option, usually guided by a psychiatrist.
What are the side effects of memantine?
Dizziness, headache, constipation and sleepiness are the most common. It can raise blood pressure slightly. Most people tolerate it well.
Information only. Not a recommendation or endorsement of any product. Whether a medicine suits you depends on your health and other medicines, so talk to your doctor or pharmacist. In an emergency, call 000 (Australia) or your local emergency number. From a mobile, 112 works in most countries.
More information
- Ebixa product information (TGA)
- PBS: Memantine
- Modarresi A et al. Memantine augmentation in OCD: meta-analysis (2019, BMC Psychiatry)
- Healthdirect: Medicines information
maladywise.com/medicines/memantine/