Memantine is used to reduce the symptoms of mild to moderate Alzheimer’s disease and other types of dementia. Learn how to use the medication, its common side effects, special precautions to watch out for, and more.

What is this medication for?

Memantine belongs to a class of medication known as N-Methyl-D-Aspartate (NMDA) antagonists. It is used to reduce the symptoms of moderate to severe Alzheimer’s disease and other types of dementia, such as:

• Difficulty in remembering recent events, activities, or the names of familiar people or things
• Poor concentration and judgement

It will not cure or stop the dementia from getting worse, but it may improve the ability to think in some patients and slow down the worsening of these symptoms.

Check with your healthcare professional if you are unsure why you are given this medication.

How should I take or use this medication?

• Follow the instructions on your medication label and take this medication as prescribed by your doctor.
• This medication may be taken with or without food.
• This medication needs to be taken regularly for a few weeks before you feel its full effects. Therefore, do not stop taking this medication even if there are no signs of improvement at the beginning.
• You may check with your doctor on how long you will have to be on this medication.
• Do not stop taking your medication without checking with your healthcare professional.

What should I do if I forget to take or use this medication?

• If you forget to take a dose, take it as soon as you remember. However, if more than half of the time to the next dose has passed, skip the missed dose and take the next dose at your usual timing.
• For example, for a medication to be taken once daily at 8am, and you missed your dose at 8am, take it as soon as you can remember before 8pm. Do not take two doses to make up for the missed dose.

What precautions should I take when taking or using this medication?

Inform your healthcare professional if: 

• You are allergic to this medication or any of the other ingredients of this medication
• You are pregnant, planning to become pregnant, or breastfeeding. If you are pregnant and/or breastfeeding, your doctor would have discussed the potential benefits and side-effects with you and should you have further questions or concerns, do consult your doctor.
• You are taking any other medications including over-the-counter medications, supplements,  traditional medications and herbal remedies. Some of these may affect how this medication works or cause serious drug interactions.
• You have or have ever had:
  • Other drug allergies
  • Medical conditions such as:
    • Heart, kidney or liver disease
    • Seizures (fits)

What are some common side effects of this medication?

• Dizziness
  • Get up slowly from a sitting or lying down position
• Drowsiness or feeling tired
  • Avoid driving or taking part in activities that require concentration
  • Discuss with your doctor if you can take your medication at a different time of the day
• Constipation
  • Drink more water (if not on fluid-restricted diet), eat more high-fibre foods, and exercise regularly
  • Speak to your doctor or pharmacist if you need a medication to help with your constipation
• Headache

Most of the side effects listed here will improve with time. Speak with your doctor if any of them continues, worsens or affects your daily life.

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 

• Swollen face/eyes/lips/tongue
• Difficulty in breathing
• Itchy skin rashes over your whole body

Rarely this medication may cause:

• Confusion
• Seeing or hearing things that are not present (hallucinations)
• Mood changes or low mood
• Seizures (fits)

If you experience any of these side effects, you should stop your medication and inform your healthcare professional immediately.

What food or medication should I avoid when I take or use this medication?

Avoid drinking alcohol while taking Memantine as it can cause excessive sleepiness.

Inform your doctor before making drastic changes to your diet. (E.g. switching from a meat-based diet to a vegetarian diet)

The following medication may increase the risk of experiencing side effects with Memantine. Discuss with your healthcare professional regarding alternative medication. 

• Dextromethorphan, a medication used for cough
• Amantadine, a medication used for the treatment of Parkinson’s disease  
• Ketamine, a medication used for the treatment of mental health conditions 

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How do I throw away this medication safely?

Pack this medication into a trash bag and seal it tightly before throwing it into the rubbish chute or bin.

Disclaimer

Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Feb 2025