Amantadine is a medication that was originally developed as an influenza drug and is now primarily used to counteract the side effects of medication for Parkinson’s disease. It can also be used to treat certain mental health conditions, including obsessive-compulsive disorder, treatment-resistant depression and others, such as attention deficit hyperactivity disorder and autism.

Amantadine brand names

Amantadine is sold under the brand names Gocovri, Osmolex ER, Symadine and Symmetrel.

What is amantadine prescribed for?

Amantadine was originally developed as an antiviral drug to treat the flu.[1]

It is used to counteract the side effects of medication for Parkinson’s disease and can be used in combination with other drugs to directly treat symptoms of Parkinson’s disease.[2]

It can be prescribed for certain mental health disorders and other conditions related to the brain, such as:[1]

How does amantadine work?

As with many drugs, the exact mechanism of action of amantadine is not fully understood.[3] It is an antiviral agent and prevents the flu virus from spreading. It affects the release of dopamine, a chemical in the brain that is involved in several processes in the body, including sleep, mood, attention and movement.

How is amantadine usually taken?

Amantadine comes in different forms, including capsules and tablets, slow-release capsules and tablets, and an oral liquid. Amantadine is usually taken once or twice a day and should be taken at the same time each day.

The dose will be decided by a doctor or mental health professional and will consider the severity of your symptoms and other conditions and medications.

How long does amantadine stay in your system?

Amantadine has a half-life of around 15 hours, on average, which is the time it takes for the body to break down and eliminate half of the dose. The half-life varies from person to person.[4]

Amantadine side effects

Like all medications,

Common side effects of amantadine include:[2][4]

  • Dry mouth
  • Constipation, nausea and vomiting
  • Less of an appetite than usual
  • Sleep problems
  • Headaches
  • Drowsiness and confusion
  • Low blood pressure
  • Muscle spasms and contractions, problems walking
  • Purple or red marks on the skin

You should discuss side effects with your doctor.

If you feel drowsy or experience blurred vision, you should avoid driving and operating heavy machinery.

Seek medical attention for the following more serious side effects right away:[2]

  • Hallucinations
  • Paranoia
  • Depression, low mood and/or anxiety
  • Suicidal ideation
  • Dizziness or fainting
  • Blurred vision
  • Swollen limbs, joints, hands or feet
  • Urinary retention
  • Shortness of breath

Some people have developed gambling problems or other compulsive behaviors after taking amantadine. Tell your doctor or healthcare provider if you become aware that you are developing intense urges to spend, eat, have sex or gamble.[2]

Amantadine precautions

Before prescribing amantadine, your doctor should discuss your medical history, any health problems you have, medications you are taking and any allergies. In particular, make sure you tell them:[2]

  • If you are allergic to any of the ingredients in amantadine
  • Any other medication you are taking, including supplements and herbal remedies
  • If you have kidney disease
  • If you have or have had a problem with alcohol or other drugs
  • If you have any other physical or mental illness
  • If you are pregnant, trying for a baby or breastfeeding

You should not stop taking amantadine suddenly, as this can cause serious adverse effects, including psychosis, muscle problems, slurred speech, and fever.[2]

Amantadine interactions

Amantadine can interact with other medications, drugs and alcohol. Make sure you discuss any medication, supplement, herbal remedies or other substances you are taking with your doctor.

Amantadine can seriously interact with the dementia drug memantine, increasing the risk of central nervous system toxicity.[5]. It can also interact with other drugs that act on the central nervous system, such as levodopa (prescribed for Parkinson’s disease).[4].

Taking amantadine with antipsychotic drugs can increase the risk of psychosis.[4]

Some diuretic medications can affect the rate at which amantadine is removed from the body, which can cause adverse reactions.[4]

Amantadine storage

Amantadine should be stored at room temperature (68-77°F or 20-25°C), away from light and moisture. Always keep medication with the original packaging to check the date and instructions for use. Keep all medication away from children.[6]

What to do if you overdose on amantadine

It is possible to overdose on amantadine. The symptoms of an overdose include:[2]

  • Increased heart rate
  • Breathing problems
  • Reduced urination
  • Swollen limbs, joints, hands or feet
  • Stiffness of the limbs
  • Involuntary movement of parts of the body, including shaking
  • Difficulty with coordination
  • Confusion
  • Disassociation – feeling disconnected from yourself or your surroundings
  • Fear or anger
  • Hallucinations
  • Feeling lethargic

If you take too much amantadine, contact the Poison Helpline at 1-800-222-1222 or seek emergency medical help immediately.

What happens when you stop taking amantadine?

Do not stop taking amantadine without medical advice from your doctor. Suddenly stopping amantadine can lead to serious consequences, including psychosis, muscle problems, and fever.[2]

Resources:

  1. Amantadine: Medication Info Sheets. (n.d.). Children’s Hospital of Eastern Ontario (CHEO). Retrieved November 15, 2022, from https://www.ementalhealth.ca/Toronto/Amantadine/index.php?m=article&ID=78757
  2. Amantadine: MedlinePlus Drug Information. (2021, June 15). MedlinePlus. Retrieved November 15, 2022, from https://medlineplus.gov/druginfo/meds/a682064.html
  3. DailyMed - AMANTADINE capsule. (n.d.). Dailymed.nlm.nih.gov. Retrieved November 25, 2022, from https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4157d9a7-a53f-4dde-b051-fe3e9a674913
  4. Amantadine hydrochloride 100mg capsules - Summary of Product Characteristics (SmPC). (n.d.). Retrieved November 15, 2022, from https://www.medicines.org.uk/emc/product/12143/smpc#gref
  5. Amantadine: Interactions. (n.d.). National Institute for Health and Care Excellence. Retrieved November 15, 2022, from https://bnf.nice.org.uk/interactions/amantadine/